Fertility false myths

Fertility false myths

Does taking birth control effect my future fertility?

Oral contraceptives (OCP’s) are using by at least 35% of women of reproductive age, (1), making it the most frequently used contraceptive method after condoms. There are many myths surrounding OCP’s but we are going to focus on their effect on fertility once we stop using them.

The measurement of Antimüllerian hormone (HAM) in patients using some type of hormonal contraception has been shown to be 19% lower than would be expected based on age (2). Normally we use this parameter, the AMH, to “measure” the ovarian reserve, so we might think that this myth is true but it has been shown that the value of the AMH returns to normal after the cessation of taking this type of contraceptives (3) without depending on the time of use of the same. Furthermore, it has been found that the probability of pregnancy after taking birth control in the past is the same as that of women who have never taken them (4).

In summary, the use of hormonal methods to avoid becoming pregnant does not affect fertility, although we must be careful in testing AMH at a time when we are not taking them to have a more reliable measurement.

Can I increase my chances of having a boy or a girl by programming intercourse?  

This is a myth that is widely heard and the “ways” in which you could try to choose the sex of the future baby vary greatly depending on where we obtain information. Perhaps the most widespread is the one that associates the moment of sexual intercourse on the day or days close to ovulation with the probability of having a boy. This theory began in 1980 with the so-called “Billings method” (5) according to which if there were close relationships to ovulation, the sperm that would be more likely to reach the egg would be those that carry the “Y” chromosome, since they are “lighter ”.

Since then there have been numerous studies trying to study this hypothesis but only one of them has found success with this method (6). The rest of the published studies (with a greater number of patients) did not find this relationship, either by this or by other methods (7) (8) (9), even a study of 875 patients (10) found the relationship just contrary.

With all this information, it must be concluded that there is no “natural” way to choose the sex of the newborn.

Drinking coffee when trying to get pregnant is bad

With regards to coffee consumption and pregnancy, the ACOG (American College of Obstetricians and Gynecologists) recommends not exceeding two cups of coffee per day (200 mg caffeine / day approx.) (11). The question may arise if its consumption, as a stimulant, can affect the chances of conceiving. It has been seen that its consumption does not modify the ovulatory pattern of women (12) nor the probability of becoming pregnant in your natural cycle (13) so that its consumption does not need to be stopped if you are trying to get pregnant, although it is recommended not to exceed the daily dose mentioned above

I’ll stop smoking once I get pregnant

We have already seen what happens with coffee, but does tobacco affect my chances of getting pregnant? The answer is yes. Tobacco use affects the female reproductive system in various ways: it decreases egg quality, increases oxidative stress on the ovary, affects the contractility of the fallopian tubes, and decreases uterine receptivity. Therefore, it has been seen that the probability of having fertility problems increases by 60% (14).

I will start taking folic acid supplements when I get a positive pregnancy test

Although the majority of women in Spain take vitamin supplements during pregnancy, less than 35% do so in the previous months (15). There is a false belief that you should start taking it once pregnant, but it should be started at least one month before conception (16) to decrease the risk of neural tube defects at the fetal level (17). Therefore, at the moment you decide to seek pregnancy, start with the daily intake of any preparation that has at least 400 micrograms of this compound.

After a miscarriage I am less likely than another woman to have a baby

The first thing to keep in mind is that, unfortunately, miscarriages are a relatively common occurrence that happen according to the latest statistics around 18.6% (18). It has been shown that the probability of becoming pregnant after a miscarriage is the same as in those patients who have never had one and even those who have a previous child (19).

On the other hand, the probability that another miscarriage will happen in this situation is the same as that of the population that has never attempted to become pregnant (20), moreover, this probability decreases if the pregnancy occurs before 4 months after the miscarriage, so that you don’t have to wait a “ safe time” before trying again.

Is it necessary to rest after performing an embryo transfer?

Now we move to myths more focused on fertility techniques, which are also very widespread. Perhaps the one we hear most in consultation is the need to rest after the transfer of an embryo (ET) to the uterus after in vitro fertilization. There is a logical doubt as to whether getting up after ET can cause the embryo to come out of the uterus. What’s more, in the 1980s it was common to recommend resting for a few days at home “just in case”.

In 2009, a study demonstrated by ultrasound that the movement in millimeters of uterine content after walking after a transfer was not different from that of those patients who had not moved from the bed (21). After numerous studies that reach the same conclusions, a review of the literature has recently been published that found the same rate of clinical pregnancy and live births in patients who were not resting compared to those who did (22).

Therefore, rest is not recommended after ET and, in general, you should carry out your normal daily activities in the following days.


  1. Johnson S, Pion C, Jennings V. Current methods and attitudes of women towards contraception in Europe and America. Reprod Health. 5 de febrero de 2013;10:7.
  2. Birch Petersen K, Hvidman HW, Forman JL, Pinborg A, Larsen EC, Macklon KT, et al. Ovarian reserve assessment in users of oral contraception seeking fertility advice on their reproductive lifespan. Hum Reprod. octubre de 2015;30(10):2364-75.
  3. Landersoe SK, Birch Petersen K, Sørensen AL, Larsen EC, Martinussen T, Lunding SA, et al. Ovarian reserve markers after discontinuing long-term use of combined oral contraceptives. Reprod Biomed Online. 15 de octubre de 2019;
  4. Mikkelsen EM, Riis AH, Wise LA, Hatch EE, Rothman KJ, Sørensen HT. Pre-gravid oral contraceptive use and time to pregnancy: a Danish prospective cohort study. Hum Reprod Oxf Engl. mayo de 2013;28(5):1398-405.
  5. Billings E, Westmore A. The Billings method: Controlling fertility without drugs or devices. Anne ODonovan Press. 1980;
  6. McSweeney L. Successful sex pre-selection using natural family planning. Afr J Reprod Health. marzo de 2011;15(1):79-84.
  7. Tiberi S, Scarpa B, Sartori N. A composite likelihood approach to predict the sex of the baby. Stat Methods Med Res. noviembre de 2018;27(11):3386-96.
  8. Gray RH, Simpson JL, Bitto AC, Queenan JT, Li C, Kambic RT, et al. Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning. Hum Reprod Oxf Engl. mayo de 1998;13(5):1397-400.
  9. Carson SA. Sex selection: the ultimate in family planning. Fertil Steril. julio de 1988;50(1):16-9.
  10. Guerrero R. Association of the type and time of insemination within the menstrual cycle with the human sex ratio ar brth. Int J Fertil. 1970;15:221-5.
  11. American College of Obstetricians and Gynecologists. ACOG CommitteeOpinion No. 462: Moderate caffeine consumption during pregnancy. Obstet Gynecol. agosto de 2010;116(2 Pt 1):467-8.
  12. Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Caffeinated and alcoholic beverage intake in relation to ovulatory disorder infertility. Epidemiol Camb Mass. mayo de 2009;20(3):374-81.
  13. Lyngsø J, Ramlau-Hansen CH, Bay B, Ingerslev HJ, Hulman A, Kesmodel US. Association between coffee or caffeine consumption and fecundity and fertility: a systematic review and dose-response meta-analysis. Clin Epidemiol. 2017;9:699-719.
  14. de Angelis C, Nardone A, Garifalos F, Pivonello C, Sansone A, Conforti A, et al. Smoke, alcohol and drug addiction and female fertility. Reprod Biol Endocrinol RBE. 12 de marzo de 2020;18(1):21.
  15. Sanfélix-Gimeno G, Ferreros I, Librero J, Peiró S. Caracterización de la suplementación de folatos en el embarazo a partir de la combinación de sistemas de información sanitaria. Gac Sanit. diciembre de 2012;26(6):512-8.
  16. SEGO. Guía de asistencia Práctica.Control prenatal del embarazo normal. Prog Obstet Ginecol. 2018;61(5):510-27.
  17. Blencowe H, Cousens S, Modell B, Lawn J. Folic acid to reduce neonatal mortality from neural tube disorders. Int J Epidemiol. abril de 2010;39 Suppl 1:i110-121.
  18. Bérard A, Abbas-Chorfa F, Kassai B, Vial T, Nguyen KA, Sheehy O, et al. The French Pregnancy Cohort: Medication use during pregnancy in the French population. PloS One. 2019;14(7):e0219095.
  19. Wildenschild C, Riis AH, Ehrenstein V, Hatch EE, Wise LA, Rothman KJ, et al. Fecundability among Danish women with a history of miscarriage: a prospective cohort study. BMJ Open. 21 de 2019;9(1):e023996.
  20. Sundermann AC, Hartmann KE, Jones SH, Torstenson ES, Velez Edwards DR. Interpregnancy Interval After Pregnancy Loss and Risk of Repeat Miscarriage. Obstet Gynecol. 2017;130(6):1312-8.
  21. Lambers MJ, Lambalk CB, Schats R, Hompes PGA. Ultrasonographic evidence that bedrest after embryo transfer is useless. Gynecol Obstet Invest. 2009;68(2):122-6.
  22. Cozzolino M, Troiano G, Esencan E. Bed rest after an embryo transfer: a systematic review and meta-analysis. Arch Gynecol Obstet. noviembre de 2019;300(5):1121-30.

Dr  María Martinez, a gynaecologist at Instituto Bernabeu.


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