Article from Laura Enrica's blog


Updated on April 14, 2016

Translation March 29, 2022


The article is exhaustive enough to be able to use ovulatory test sticks both to detect ovulation and as early pregnancy tests.

In the following a new, but more effective, stick reading criterion is suggested, compared to the one based on the LH peak alone. 

The criterion allows you to allocate sexual intercourse on fertile days in a more effectively manner for the purpose of conception.

The new criterion is based on both the reading of the LH hormone and estrogen (precisely estrone E3G) so it criterion cannot be applied with sticks that reveal only the LH hormone.

This criterion is amply justified and detailed to show that it is much more effective in increasing the likelihood of conceiving than the only LH surge criterion.

NOTE: Since the article may be too detailed in the reasoning made, for those who do not intend to deepen it is suggested to focus their attention on the bold phrases, the latter constituting the conclusive suggestions to follow in the search for a pregnancy.

Finally, the article will also specify why the use of the well-known LH peak reading criterion may not only be ineffective at times for conception purposes (as also confirmed by recent studies on hormones detected by ovulatory sticks) but, according to Shettles' method, it seems to provide a much higher probability of having a son than the probability of having a girl.

This article also reports various curiosities and information, including the TB measurement a few days before childbirth (which should be studied in deep, in order to predict the onset of labor) and interesting considerations on the dynamics of the menstrual cycle. This last information should not be underestimated because it can be really useful for being able to interpret the signals of your body in view of conception.

Note on digital indicator sticks (laughing face)

The stick indicators that show smiley faces both for products with a single indicator (detection of the 2 most fertile days) and in particular those with a double hormonal indicator (4 fertile days) can be misleading, because they make us lose an important information, that of the intensity of each single line, which must also be interpreted according to the phase of the cycle in which one is.  The most effective reading of the sticks certainly derives from the direct observation of the more or less charged tone of the lines, supported by the information of the blog, by a forecast calendar of one's monthly cycle (a prospectus that can be requested free of charge), common sense and knowledge of ourselves. Not doing this runs the risk of relying on a smiley face that often appears in the most unexpected moments, creating perplexities that cannot be interpreted by the single digital indicator that smiles. Our reasoning, on the other hand, combined with careful observation, is the most effective way to get to know our body better and to search for the desired pregnancy in a more targeted and effective way.

Note on the duration of the useful period for having intercourse by reading only the ovulatory sticks

As will be argued later, the four fertile days detected by the dual hormone indicator sticks, as well as the two fertile days detected by the single indicator sticks, correspond respectively to 3 days and 1 day useful for having intercourse, being the arrival time of the sperm to the fallopian tubes about a day. The topic will be deepened to make some clarifications and outline the rules of behavior in order to have relationships aimed at conception based on the results of the sticks.

What are test sticks

Test sticks are urine tests. Once removed from the protective wrapping, they look similar to the one in the figure. The test window is shown from the left, followed by the absorbent tip and test cap to the right.


The tests are carried out on the urine, to evaluate the probable ovulation through the presence and the comparison of the quantities of two hormones. Sticks can also indicate a probable pregnancy, because the stick reagent also binds with the pregnancy hormone, as well as with the LH hormone.

The absorbent tip of the sticks should be placed for about three seconds under the flow of pee or immersed for fifteen seconds in a glass where the urine was collected. The cap must then be removed from the test window to position it so that it covers the absorbent tip. The stick should be left lying on a surface waiting for the reading of the test window. After about 1 minute, at least one or two vertical lines (more or less intense) appear.


Hormones detected by the test

The left line detects estrogen (more exactly Estrone-3-Glucoronide indicated with E3G) while the right one detects LH (Luteinizing hormone).

E3G is a hormone produced by the ovaries (like Progesterone), while LH is produced by the pituitary gland (like FSH hormone).

For technical reasons the functioning of the two lines is inverse: the one on the right (LH) increases in intensity as the concentration of LH increases, while the one on the left (E3G) decreases in intensity as the concentration of LH increases.

Ovulatory sticks reveal estrone present in the urine as E3G is the quantitatively most important component of estrogen to detect ovulation 3 days early. However, the trend of estrone is qualitatively similar to that of estradiol in the days preceding ovulation, except for the location of the relative hormonal peak, which for E3G roughly coincides with the LH peak, while for estradiol anticipate it by a day or two at the most, as I will explain below.

It will therefore be useful to know the trend of estradiol, rather than E3G, as the latter also influences the quantity and characteristics of the fertile mucus, which will be abundant, stringy and transparent especially one or two days at most from the peak. of LH of the sticks.

Furthermore, since the E3G trend is qualitatively similar to that of estradiol as ovulation approaches, it is expected that a stick with a faded left line (increase in E3G) also corresponds to an increase in fertile mucus (stringy, abundant and transparent, called "egg white." This allows you to cross-check with multiple methods of observation of your body, in order to verify that ovulation is approaching.

Hormonal trend as a function of (probable) ovulation

When ovulation is still a long way off:

a) the left line is marked

(the level of E3G and therefore also of Estradiol which has a similar trend to E3G, indicated with the red dotted line in the graph, is low)

b) the right line is absent

(the LH level is low, as indicated by the solid blue line).


As ovulation approaches, the right line intensifies (increases LH) and the left one fades (increases E3G and also Estradiol) .When the left line is very faint or absent (there is a lot of 3EG ) and the right line is very intense (there is a lot of LH) means that ovulation is imminent (or, as we will see later, probably already in progress). In fact, ovulation occurs 36-48 hours after the estradiol peak (weak or absent left line) and 12-24 hours after the LH peak (marked right line) as found in the graph above. Therefore, when the stick highlights the right line (LH peak) ovulation occurs on average, (12 + 24) / 2 = 18 hours later.

Recent studies have corroborated the aforementioned calculations, placing the LH surge at about twenty hours (on average) from ovulation.

It will be specified below that the aforementioned hormonal behavior does not imply the certainty of the occurrence of ovulation, although it represents a necessary condition for the latter to occur (for this reason we speak of "probable ovulation").

Using test sticks to conceive a child

Each test is usually repeated every 24 hours so the result, used in order to identify the best time to conceive, could be very approximate. In fact, a test reading made for example in the morning can also indicate a hormonal state already present in the early afternoon of the previous day and not highlighted by the stick of the day before (because it was also done for example in the morning).

Here are some counts to understand, based on the right line of the sticks, when the fertile period ends, in order to ensure potentially fertile intercourse ...

To calculate the moment that, on average, based on the test result, is the most suitable for conceiving, we take an average value between the moments in which two consecutive test sticks are carried out (for example, of the current day and the previous one. ) that is 12 hours. In other words, suppose that, on average, the result of the stick carried out every 24 hours is indicative of a hormonal state that has persisted for 12 hours.

It follows that the marked right line is indicative of ovulation which, on average, can only occur 18-12 = 6 hours after taking the test. Since the life span of the ovule is 24 hours (at most) and the time taken by the spermatozoa to reach the fallopian tubes is 24 hours, it is evident that fertilization occurs almost at the limit of the average life of the ovule (which will die within 6 hours after the arrival of the spermatozoa).

In cases where the ovum lives for less time (it can live even 12 hours only), it is evident that a stick with the right line marked, carried out every 24 hours, may not be used in order to have fertile intercourse.

Among other things, with the gradual aging of the ovum (over 24 hours), the probability of conception decreases rapidly, so a stick with only the right line marked indicates that it is very probably late to conceive, especially if intercourse they do not occur immediately after the test, but throughout the day or even in the evening (therefore about 12 hours after the stick).

It should be noted that the 18-hour average value of the LH peak from actual ovulation is calculated considering the case of double ovulation. Surely in this case a second ovum will also be available but certainly, having not exploited the first ovulation with adequately anticipated intercourse, the probability of conceiving has not been optimized.

The interval of 18 hours between LH surge and ovulation will generally be lower in the case of a single ovulation (it also goes to an average value of 16 hours so in the above calculations the ovule is only four hours old when the spermatozoa arrive, provided he lives 24 hours and no less).

The reasoning made is based on statistics and the calculations made are valid on average, not for all cases.

From the "average" case just treated we can conclude that a relationship that optimizes the chances of conceiving, that is, which causes the spermatozoa to reach the tubes when the egg is at the beginning of its life, must take place 18-20 hours before the stick. positive (right line marked) if the sticks (in order to find the right line marked) are performed every 24 hours

Let us now evaluate cases as far from the average values ​​as they are more unlikely.

One of these is a "pessimistic" case (for those who intend to conceive a child): suppose that the morning test (with the right line marked, indicative of the LH surge) indicates a hormonal state that has already existed since the afternoon of the day before, for example more than 12 hours earlier, and ovulation occurred, as expected in the worst case, 12 hours after the LH surge (remember that the interval between the LH surge and ovulation is estimated at 12- 24 hours). In this case the stick (with the right line marked) indicates that ovulation is already in progress and, despite having intercourse immediately after the test, the spermatozoa will arrive at the tubes 24 hours later (when the ovule is already dead, much more if it has a life span of less than 24 hours).

Another case, as "optimistic" as (according to statistics) less probable, is the following: the test with the stick done in the morning is indicative of a hormonal change that took place the same morning, ie the marked right line indicates a concentration peak of LH which is happening in the morning. Ovulation will occur at the latest 24 hours later and the egg will live, at most, another 24 hours. Having intercourse immediately after the test, the spermatozoa will arrive at the tubes at the beginning of the ovule's life and the chances of conception will be optimal. Another concomitant favorable situation would occur in the case of double ovulation, since the release of the second ovule occurs within 24 hours of that of the first ovule.

This last "optimistic" case clarifies how in general a test stick similar to the one in figure 4 (right line marked) indicates that, most likely, it is late to conceive: on average, as we have seen, by 18-20 hours ( 20 for single ovulation) if the test is done every 24 hours.

NOTE: Some websites refer to the concept that uterine contractions during intercourse speed up the movement of spermatozoa, however, in my opinion, they gradually flow through the cervical canal, long after intercourse.


With simple calculations it was possible to prove that 

if the probability of conceiving is, on average, optimal 18-20 hours before the LH surge found on sticks carried out every 24 hours, intercourse should take place, on average, as much earlier than the peak in question in order to result, with the highest probability, effective to conceive.

In this way, intercourse would precede ovulation by 36-38 hours because between the LH surge and ovulation another 18 hours pass, on average. In this case, the ovule would arrive to be fertilized when it is at the beginning of its life and the probability of conception is optimal, as indicated in the green area of ​​the graph in figure 5. In particular, it should be observed that the aforementioned temporal distance from 'ovulation (36-38 hours) falls right in the center of the green area and this is understandable since intercourse adequately anticipated (but not too much) exploits the life expectancy of spermatozoa (which however on average exceeds 3 days) while intercourse postponed with respect to the aforementioned interval (36-38 hours) have an efficacy that depends on the variability of the temporal distance between the LH peak and ovulation, as well as on the duration, albeit short, of the ovule's life.
For the above reasons, the period with the highest probability of conception, that is the optimal one for conceiving, is affected by a margin of variability and is about a couple of days wide.


It follows that the LH surge, although fairly precise in indicating the event of ovulation, may not guarantee in several cases expected to be fruitful. For this reason I provide the following suggestion:

when the LH peak is expected, the sticks should be repeated every 12 hours, instead of 24 hours, in order to identify this peak as soon as possible, furthermore intercourse should take place as close as possible to the stick (if for example the stick is done in the morning, intercourse in the evening may not be effective for conception).

With the aforementioned precautions one should ensure that they have had potentially fertile intercourses. For the most accurate identification of the end of the fertile period, sticks with a single hormonal indicator (i.e. those that detect only LH) could be used which, having to be done every 12 hours, are at least cheaper.

How to find the ideal time to conceive a child from the left stick line

Some accounts to understand, based on the left line of the sticks, when to have potentially fertile intercourses ...

According to the calculations made on the average values, ovulation occurs (36 + 48) / 2 = 42 hours after the estradiol peak. Since the stick detects the rise in E3G approximately 3 days (i.e. 72 hours before ovulation), the faded left line of the stick is expected to precede the estradiol peak by 30 hours, i.e. approximately one day.

Considering that the test is carried out every 24 hours and that, on average, it is indicative of a hormonal state that has lasted for 12 hours, even for the estradiol peak, we can say that ovulation occurs, on average, 42-12 = 30 hours from the estradiol peak, i.e. 30 + 30 = 60 hours from the faded left stick line (E3G increase)

Finally, since the accounts have been carried out considering a maximum duration of the life of the ovum (which can be even less than 12 hours, with advancing age), then the probability of optimal conception occurs even before the preceding 36-38 hours. ovulation, in particular you can have 38 + 12 = 50 hours before ovulation (that is, on average, about two days before ovulation). This means that in the worst conditions of life span of the egg between the faded left stick line (E3G increase) and the beginning of the two days with the highest probability of conception (green area), as little as 10 hours can pass.

For this reason it can be concluded that the beginning of the period with the highest probability of conception (which, as already specified, ends about 20 hours before the LH surge) occurs 22 hours after the E3G increase (left faded stick). It is therefore reasonable to state that the optimal probability of conception occurs, in principle, in correspondence with the increase in estradiol even many hours before its peak (see Fig. 3). Using the information that can be obtained from reading the sticks, the following criterion can therefore be applied:

When the left line begins to fade (increase in E3G estrogen before its peak), the optimal period to conceive is about to begin (green area in Figure 5).

When the right line begins to rise (LH surge) the optimal period is ending (and with it the fertile period ends quickly).

When the right line begins to fade (after the LH surge) it is very likely that intercourse will not be fertile.

To give an example, the test sticks in figure 6 indicate that the period with greater fertility is, indicatively, between 11 evening and 13 evening (while ovulation, according to what the sticks indicate, should have occurred in the early hours of day 14).

Note that (Fig. 6) the days with most likely conception are indicated in red, the LH surge occurs on days in blue color. The fertile period ends on the evening of the day indicated in green.

So the days circled in red correspond to the period that begins about two and a half days, before ovulation and lasts about two days, as indicated by the green area in fig 5.


From what has been detailed so far it can be deduced that

the stick reading method based on the increase of E3G is always valid for the purpose of pregnancy research as it ensures potentially fertile intercourses...

... since it still covers the green area of ​​fig. 5. For this reason, the sticks with double indicators, although they are more expensive, are the only ones (unless other methods of observation of one's body, of course) that allow you to indicate early enough when to have potentially fertile intercourses.

While single indicator sticks are recommended to accurately identify the end of the fertile period, double hormone indicator sticks allow you to identify the beginning of the period with a higher probability of conception (this is a thing that sticks with single hormone indicator cannot to do).

In particular, if the increase in E3G is detected as soon as possible, and choosing to have intercourse every other day to maximize the chances of conceiving, it is preferable to have the first intercourse in correspondence with the fading of the left stick line, in particular as much as possible to close to the stick, so that the next intercourse would fall at or just before the LH peak, while still being adequately spaced from the first intercourse.

In this way, with the use of sticks alone, the days of the two most fertile intercourse could be identified and adequately spaced apart in order to maximize the number of spermatozoa present at the release of the oocyte.

It should be noted that outside the period with the highest probability of conception, it is not certain that you will not be able to conceive anyway!

In fact, the period with the highest probability of conception is included in the period indicated as the fertile period, the latter being however wider. In particular from fig. 5 it is seen that it begins 6 days before ovulation and ends one day after, as it considers that the life of the ovule is 24 hours. In the case of double ovulation, the graph could extend to an even longer period (up to two days later) as the two ovules are produced within 24 hours of each other at most.
The arguments made up to now on the timing of conception do not justify such a large fertile period (6 or 7 days) in fig. 5 but only the green area. 

However, in fact, and fortunately, it exists thanks to the life expectancy of spermatozoa which is between 3 and 5 days, on average, but which can even reach 7 days.

It should also be noted that the extremes of the fertile interval have almost nil probabilities of conception, so if you are looking for a pregnancy in the shortest possible time, it is useful to identify the period with the highest probability of conception, even if it would be preferable to exploit the entire fertile period, in particular the days preceding the green area of ​​fig. 5 (especially when a female child is desired, as detailed below).

In fact, exploiting the entire fertile window means "playing in advance", both to maximize the number of intercourse, and therefore of spermatozoa, and to better cover the window of uncertainty of the ovulation event, which is a statistical event of which the exact timing is not known (except for ultrasound scans).

As indicated in the example of figure 6, it should be observed that the more frequent use of the tests (for example one every twelve hours, instead of 24) allowed to detect both the increase in E3G and the LH peak twelve hours earlier (the evening instead of the next morning) compared to a use of the tests done for example every morning, or every 24 hours. In this way, both the beginning and the end of the most fruitful period are identified with greater precision.

Expert readers in the use of sticks know the trend of the lines in their fertile window. Once they have verified the increase in estradiol, they know that on average two days pass before the LH surge, so they will not do the sticks every day. In fact it is sufficient, once the increase in E3G is detected, that the LH surge directly occurs on the day known to them. This saves on the cost of testing.

For example, the first two tests in the figure below show the increase in estradiol before the peak, from this to the LH peak stick (third stick from the top), for example, as usually happens, two or three days (i.e. the stick was done directly on the day the LH peak was expected). The last stick only confirmed the end of the LH surge (which could be detected for more than a day) which corresponds to the day of probable ovulation.

The new stick reading criterion does not consider the search for the LH peak, that is the dark right line of the stick, but the fading of the left line, corresponding to the increase in estrogen before their peak.

At this point it is useful to know when to start using test sticks as a fertile period test. The suggested criterion is the following:

I) For regular cycles, the day on which to start using the stick to identify the fertile window must precede ovulation by 4 or at most 5 days (cycle length - luteal phase duration - 4 or 5 days)

II) For irregular cycles, the day to start sticking is = duration of the shortest cycle - the duration of the longest luteal phase - 4 or at most -5 days.

It is clear that the more irregular the cycle, the "wider" the fertile window will be, but this increase of width is not effective as it depends only on the uncertainty about the day on which ovulation will occur. 

The uncertainty about the location of the fertile window may involve the use of several extra sticks before identifying the fading of the left line so in some cases it is advisable to use only the prospectus of your cycle (calculated and provided free of charge) having reports by days alternate (or at most two days no and one day yes) within the "widest" fertile window.
The calculation of a fertile window end of a "more wide" fertile window is free provided when you ask a montly cycle report in excel by

The fertile week typically begins, and in particular referring to the case in figure 6, the day before (or at most the same day) of the first stick at the top, in which the left line is still dark. So the stick with the left line still dark would correspond to the second day of the fertile window. On the third day of the fertile window the left line typically fades, on the fifth fertile day the stick is repeated to check the LH surge, on the sixth day ovulation occurs, on the seventh day the egg dies and the fertile window ends.
From what has been specified it can be deduced that the sticks with double hormonal indicator, even if they cover the most fertile period, do not allow to exploit the entire fertile window.

In the considerations made so far, it has been assumed that ovulation has always occurred. However, it should be considered that there are cases in which the test detects an LH surge but ovulation does not occur. To be sure that the cycles are ovulatory, it is necessary to resort to ovulation monitoring with ultrasound or hormonal tests.

However, a valid alternative to monitoring or hormonal tests is the measurement of the basal temperature. For those who know the characteristic values ​​of their basal temperature (which vary from woman to woman) it is sufficient to check (for at least 3-4 consecutive days and in the week following ovulation detected by the tests) if this maintains the high values, typical of a luteal phase of an ovulatory cycle. The permanence of a high temperature (3-4 days) is indicative of the increase in progesterone, a hormone still different from those detected by the stick and produced by the ovary (in particular by a gland called the corpus luteum) together with estradiol (fig . 7).

The graphs above within the fig. 7 shows the trends of the hormones produced by the pituitary, in the lower graph there is the trend of hormones produced by the ovary.


It is therefore useful to proceed as follows:

After the LH peak (right line marked), wait a week and measure the basal temperature for a few days (3 or 4) in order to verify the increase of at least 2-4 tenths of a degree compared to the follicular or pre-ovulatory phase of the cycle. This increase, together with the information provided by the test sticks on estradiol and LH peaks is indicative of an actually happened ovulation.

After ovulation, within a few days, the left line of the stick intensifies again (reduction of E3G) while the right line is attenuated until it disappears or almost disappears (reduction of LH). The "almost" is justified by the fact that the LH levels, although low, are still subject to slight fluctuations perceptible by the test; in particular, the concentration of luteinizing hormone can increase in the afternoon, while it is reduced in the morning or when you have drunk a lot (urine too diluted).

Furthermore, if you have undergone an ovulation stimulation treatment, the result (LH surge) is no longer reliable and can give rise to false positives of the sticks.

Using the test stick as an early pregnancy test

Near the arrival of menstruation (12-13 post-ovulation), the LH increases so that the right line may be more visible. For this reason, the presence of the right line in the post-ovulatory period (generally faded but present, or even marked in the case of polycystic ovary, making the test unreliable) is not necessarily a sign of pregnancy.

The image below illustrates a case in which the right line is present but there is no ongoing pregnancy.


From 11-12 post-ovulation it is possible to use the stick as an early pregnancy test. Generally, in the event of pregnancy, you will have a stick with a right line that begins to intensify around 11-12po. In this case, a sufficiently sensitive pregnancy test (i.e. that detects even very small quantities of BHCG) will be positive even before the intensity of the right line in the stick exceeds the left (i.e. before the stick is positive as an indicator of pregnancy. ).

Furthermore, in the case of pregnancy, the left line weakens, in some cases, until it disappears. The left line weakens due to the increase in estrogen, typical in pregnancy (as in ovulation). However, this increase will generally be contained and gradual in the early stages of pregnancy.

For example, note that in the single stick in figure 9 (11 post-ovulation), although there is an ongoing pregnancy (BHCG in circulation) and the right line is evident, the left is more marked, as the estrogenic increase is not yet happened. The increase in 3EG will, as mentioned, be gradual and will be evident 8 days later (19 post-ovulation).


In pregnancy, from 11-12 bit the right line, albeit slight, intensifies more and more, making it more visible than the left. The stick in case of pregnancy looks the same as a stick in the presence of ovulation. In this case, however, the right line no longer detects only the LH hormone but also the BHCG hormone (Chorionic Gonadotropin), the increase of which makes the right line gradually more intense.

The LH in fact remains roughly constant, although undergoing small variations throughout the luteal phase, so it is likely that the right line will disappear throughout the day. If otherwise there is also BHCG in circulation (even if still a little), the right line does not disappear.

From 11-12 p.o. it may be useful to carry out the test stick two or three times, distributed throughout the day.

In general, if the right line disappears during the day, it is likely that only LH will be detected, while if it persists (even if it is not very evident) it is possible that a pregnancy has occurred.

With these shrewdness, the stick can, with less expense than an early pregnancy test, lead to the assumption of an ongoing pregnancy as early as 11-12 p.o. It is clear, however, that an early pregnancy test detects with certainty the presence of BHCG, while the stick (even if sufficiently sensitive) is unreliable since the 11-12 pregnancy hormone is still in low concentrations in the urine. and could be confused with LH.

In pregnancy, on average, after 11-12 months the BHCG is continuously increasing and this causes the stick to become positive (right line more marked than the left) within a few days.

The stick used as a pregnancy test is considered positive if the right line is more intense than the left.

It is not important how intense or faded each line is but the comparison between the lines.

It is also useful to point out that, when the LH is unusually high in the post ovulation (for example in the case of polycystic ovary or in other situations that create hormonal imbalances, such as ovarian stimulation) the stick can also become positive (right line more intense than the left) but the pregnancy test will still be negative because, while the pregnancy test indicates the Beta-HCG hormone, the stick indicated in this case only the abnormal LH value.

There are diversified and less sensitive ovulation test sticks than those covered in this article. The latter, although they detect BHCG later (beyond 11 p.o.), are more "reliable" (although not like pregnancy tests) for detecting an ongoing pregnancy.
The figure below shows a series of tests carried out in a case of pregnancy (following a pregnancy test carried out at 11 p.o. and positive result).

In figure 10 it is written that the right line is always visible and increases in intensity until the test is positive at 15 post ovulation.


Another example of stick (carried out from 10 to 12 p.o.), in case of pregnancy, is the following (fig. 11).

In this example, both lines are very faded, the right line still exceeds the left line in intensity and the test is positive.


This means that when the increase in estrogen in pregnancy is faster, the test stick becomes positive earlier than a pregnancy test stick in which the increase is more gradual.

In the event that ovulation occurs late, even if pregnant (from a pregnancy test) it is possible to have a negative result of the stick as in figure 12 (test carried out on the 27th day of the cycle, very similar to a test of the 13 po in the absence of pregnancy in figure 8 and with a regular cycle).

In this case, the attenuation of the left line and the intensification of the right will take place with a delay of a few days, as was the case with ovulation. Monitoring ovulation therefore allows you to understand whether any positive test stick will be delayed or not.


Monitoring the days of ovulation with sticks helps to correctly interpret the results when the sticks are used as a pregnancy test.

Please note that the positivity of the pregnancy test depends on its sensitivity. Very sensitive pregnancy tests detect BHCG even if the test stick looks like the figure above. The less sensitive pregnancy tests can generally still give negative results even if, despite being pregnant, the sticks have the two lines of approximately the same intensity (or even the right more marked than the left).

Example of using test sticks to search for a pregnancy

In the example below (fig.13), a test stick was used a few days after the pregnancy test to detect the increase in Beta-HCG by increasing the intensity of the right line.


The line shown in the figure 13, at 22 p.o. it is the darkest possible so it will be useless to repeat the test later because you would always observe a right line with the same intensity. It should also be noted that the left line is absent as a consequence of the increase in estrogen as the pregnancy progresses.

This is also the reason why test sticks gradually show the right line darker than the left in case of pregnancy.

Example of basal temperature measurement to detect a pregnancy

The graph below (Fig. 14) is indicative of an ovulatory cycle (with pregnancy) of the expected duration of 32 days (with ovulation occurring between the 18th and 19th day of the cycle, as detected by the subsequent echo of the blastocyst). It is observed that the average value of the basal temperature after ovulation (dashed blue line) increases by about 2 tenths of a degree compared to the follicular phase. A further increase is detected in correspondence with the expected menstrual cycle (indicated with "M" in the graph) and remains so for at least the following three days of delay (indicated with "R") in the case of pregnancy.


Curiosity on the measurement of the basal temperature in pregnancy and before childbirth

Progesterone, having the function of "maintaining" what is in the uterus (until it is reduced in proximity of menstruation) in the case of pregnancy remains high to "keep" the fetus inside it. In the last 3-4 weeks of pregnancy, progesterone gradually decreases and then decreases more rapidly in the last 3-4 days, thus favoring, in conjunction with other hormones, the onset of labor. Since progesterone is thermogenic, i.e. connected to the basal temperature, the measurement of the latter can be indicative of the approach of childbirth, reducing in a similar way to the reduction of progesterone specified above. Therefore, the measurement of the basal temperature is not only useful for indicating whether ovulation has occurred, but can also could be indicative for assessing the approach of childbirth, in particular in the last 3-4 days. This aspect should not be underestimated and should be better investigated because it helps us to foresee the approach of this very important moment in order to organize ourselves in the best possible way.

In the presence of pregnancy, the measurement of TB can be useful to prevent premature births and miscarriages due to an abnormal decrease in progesterone. However, the TB measurement is not intended as a substitute for blood tests to detect progesterone levels in women who have pregnancies at risk from this point of view. Measuring TB helps prevent progesterone lowerings that are as risky as they are easy to avoid (for example, through vaginal pessaries that release progestogens).

Other curiosities about tests stick and the menstrual cycle

a) high estrogen (left test line faded after about 7 min) does not necessarily indicate a pregnancy but can also be indicative of the arrival of the menstrual cycle. For this reason, the test detects a pregnancy early only by comparing the two lines and not by the fact that only the left line is faded. Even the stringy mucus of the ovulatory type that can be found after 7 po, being related to the high concentration of estrogen, can indicate both a pregnancy and the arrival of menstruation. In any case, high estrogen is a positive sign because it improves the quality of the endometrium in the luteal phase and is therefore a good sign for the possible implantation of the blastocyst.

b) as an alternative to test sticks as early pregnancy tests, the basal temperature which remains high for up to 16-17 days after ovulation can reasonably lead to pregnancy. Beware, however, that the temperature can remain high until the day the period arrives, therefore if ovulation or the duration of the luteal phase (which can vary from woman to woman and from cycle to cycle, especially for those with irregular cycles) does not are known exactly, it can happen that false hopes take over.

c) it is important to pay attention to the length of one's luteal phase (or luteal - calculated as the difference between the duration of the monthly cycle and the day of ovulation). In fact, the luteal phase must be long enough to allow nesting to occur with the required times. The times for nesting on average are: (1-6 p.o.) passage of the egg in the fallopian tubes and arrival in the uterus of the fertilized egg which in the meantime has transformed into a morula and then into a blastocyst; (7 p.o.) apposition phase in which the blastocyst rests on the endometrium; (8 p.o.) adhesion phase in which the blastocyst attaches to the endometrium; (9-10 p.o.) invasion phase in which the blastocyst inserts itself into the endometrium, ending the nesting process optimally at 14 p.o. 

From what has been said it can be deduced that the luteal phases of 10-11 days are considered sub-optimal and under 10 deficient, while under 7 seriously insufficient. The sub-optimal luteal phase (10-11) is however more frequent than one might think so it must be kept under control in ovulatory cycles. The luteal phase is instead usually shorter in anovulatory cycles (as the increase in progesterone does not occur and consequently the endometrium flakes off earlier) so in these cases it should not be taken into consideration.

d) in the luteal phase, progesterone plays an important role in maintaining the endometrium (preventing it from falling apart and menstruating) so that (together with the action of estrogens) it can result in favorable conditions for the onset of pregnancy.

e) the quality of the follicle (as well as that of the endometrium) also depends on the level of estrogen

f) in one year two or three cycles are usually anovulatory and one has double ovulation.

g) for those who have preferences on the sex of the unborn child it is useful to know the graphs below which, in conjunction with the fertile days, provide the probability of having a boy or a girl. Note that there are no fertile days in which, having intercourse, you are sure to have a boy or a girl, but only fertile days in which it is more likely to have a boy than a girl and vice versa.

Shettles Method

I have chosen to present this method because of a logic that underlies it and that I illustrate in the follow. It is clear, however, that it is always a question of probabilities, not certainties, of having a male rather than a female

From the graphs in the figure below (Fig. 15),where the Wilcox graph is compared to that of Shettles, it is evident that the closer the intercourse is to ovulation, the more likely it is that you will have a male, the more the relationship is prior to ovulation and the more likely it is that you will have a female.

So if you want a male it will be preferable to have intercourse as close as possible to ovulation (with the possibility of reaching the limit of the life of the ovule); if you want a female, it will be preferable to have intercourse as much as possible before ovulation (compatibly with the duration of the fertile days shown in figure 5; with the possibility that the spermatozoa cannot live long enough to reach the ovule). The explanation for this lies in the fact that the sperms carrying the Y and X chromosomes have different characteristics: the Y spermatozoa are statistically faster but live less so when they reach the tubes, if they find an already existing ovule, they are more likely to fertilize it because they arrived before the X spermatozoa. Conversely, the X spermatozoa are slower but have a longer life, so they also reach the tubes and, if the ovule is slow to form, statistically survive the Y spermatozoa and have more probability of fertilizing the ovule. Finally, it should be noted that the use of test sticks to conceive with reference to the right dark line (LH peak) predisposes to having a male rather than a female.


The details and calculations have only served to motivate the precautions on the use of test sticks so that they are effective both as indicators of conception and as early pregnancy tests. In fact, if you have enough time and patience to read the whole article, it is important to use your reasoning to convince yourself that the proposed measures are well founded and amply justified and that they are not rules based on nothing to believe in just because someone has said it is. This is important because, even if intercourse took place on the right days (fertile days) and ovulation occurred, the probability that a fertile couple will become pregnant varies from 1 in 4 to 1 in 6 cases. Therefore it is not certain that the proposed measures are successful "at the first try" since, even with the best conditions, in the less fortunate cases, the attempts must be made for several months. So how can you adopt the same method with serenity and continuity over time if you are not convinced that it can work? So, once you understand and have a way to proceed, all the details and justifications are no longer needed. What is needed is only to focus attention on a few essential precautions in order to avoid excessive second thoughts and anxiety.

In summary, the precautions on the use of test sticks and on the detection of the basal temperature (for those interested in getting pregnant and realizing it as soon as possible) concern:

1) how and when the test lines should be read to understand when to have targeted intercourse and when the presumed ovulation occurs. Remember that the test is able to predict ovulation to have intercourse but is not able to identify if this will happen with certainty;

2) when the basal temperature should be taken and how it should be interpreted to confirm that ovulation has occurred. Remember that the basal temperature is not able to predict ovulation (this is why tests are used), however, one week after the LH peak (and usually even a few days earlier, so those who have patience to take the temperature it can start earlier, but it could still wait a few days before seeing that the temperature increase has stabilized), already allows you to establish if ovulation has really occurred and therefore if in the following days there will be a real possibility of pregnancy;

3) use of the tests as early pregnancy tests from 12 po in the case in which the basal temperature has undergone the typical increase of the luteal phase (ovulation occurred). Note that 12 po is accurately determined because ovulation could be detected with the sticks. In this way you avoid using the tests unnecessarily in cases where ovulation has not been detected or occurred with delay (so what is believed to be a 12 po stick is, for example, one of the 7-8 po, whose reading is useless for predicting pregnancy);

4) as far as possible, put aside anxiety and choose the moments in the day in which to have intercourse with the greatest intensity and involvement possible (this trick was not specified in the article but it is important because it greatly influences the number of spermatozoa). This aspect is even more important than the one in which it is suggested to have intercourse every other day to improve the quality of the spermatozoa.