Using birth control pills during a fertility treatment may seem counter-intuitive, but in reality, they have often been prescribed. This has become a common practice and even a standard procedure in some fertility clinics. However, doing otherwise – undergoing IVF without birth control – may even lead to more successful outcomes.
IVF success rate without birth control may be even higher than with use of birth control pills. Some studies found that the chances of getting pregnant with spontaneous menses (natural and uncontrolled) can be as high as greater than 60%; whereas with controlled menses prior to IVF, the chances of success are only above 50%.
This article will explain the possible benefits of birth control before an IVF cycle. It will also provide statistics regarding the success rate of cycles aided by oral contraceptives and those that are not. Lastly, it will discuss why birth control pills are not always beneficial as treatment prior to IVF.
Benefits of Using Birth Control Pills Before IVF
Oral contraceptives (OCs), commonly referred to as birth control pills (BCP), are often used to aid fertility treatment methods such as IVF. However, not all OCs can be used for this purpose. The most commonly used OCs to aid IVF are monophasic types, which contain equal amounts of estrogen and progestin per pill, ensuring that a consistent amount of these hormones is maintained in the patient’s body.
Taking OCs before the stimulation stage can aid the IVF cycle through the following:
- Reduce the risk of cyst formation in the ovaries
Ovarian cysts may result in abnormal ovulation cycles, which negatively affect the woman’s fertility. Birth control pills may protect from development of functional ovarian cysts, however, they do not cure existing ones.
- Ensure equal maturation rates of the ovarian follicles
Follicles are the sacs in the ovaries that contain the eggs. Normally, one follicle will dominate and grow faster than the others, and may even cause the other follicles to stop growing. At the end of a woman’s regular cycle, a single follicle will produce only one mature egg.
With the use of OCs, the follicles are ensured to grow at equal rates. Thus, more than one mature egg can be retrieved for the IVF cycle.
- Make the ovaries more responsive to stimulation
By using OCs before the ovarian stimulation, the growth of follicles in the ovaries is temporarily halted. This break enables the ovaries to respond better to the stimulation medications, producing a greater number of mature eggs for the IVF cycle.
- Enable easier scheduling of the IVF cycle
The use of birth control pills can provide better control of the timing of the cycle. By scheduling the IVF cycle, the egg retrieval process can be set to a specific date; thus, removing the need for patients to take unnecessary day-offs from work and ensuring availability of laboratory personnel and equipment.
Success Rate of IVF without Birth Control
As mentioned above, there are several reasons why OCs are prescribed before an IVF cycle. It has become a widespread practice among fertility clinics, but some specialists still prefer to do the cycle without birth control.
Several studies have been conducted to analyze the effect of using birth control pills on the rate of successful pregnancy and the rate of live birth. Most of these studies claim that in terms of success rate, the difference between IVF with OC and IVF without OC is not significant. Nonetheless, the results show that IVF without OC can be more successful.
In 2011, the American Society for Reproductive Medicine (ASRM) published a study regarding the effect of OCs in women undergoing fertility treatment. The study was designed to determine the effectiveness of OCs as a substitute for the long-term protocol used in scheduling an IVF cycle.
To ensure the accuracy of the results, ASRM used comparable groups of patients. There were 115 patients who used OC prior to IVF (OC group), while there were 113 patients who did not take OC before IVF (non-OC group). The two groups had comparable demographic data, as to age, body mass index (BMI), and previous IVF attempts.
Results of this study showed a pregnancy rate of 53% in the OC group 4 weeks after embryo transfer, and 59.3% in the non-OC group. Pregnancy of more than 12 weeks age of gestation was 47.8% in the OC group while 53.9% in the non-OC group. Live birth rates were 44.3% vs. 47%, respectively. Success rates were found to be slightly higher in the non-OC group, however, these differences were not statistically significant.
In 2017, another study was conducted by Wei et al. to determine the effect of OCs on the success rate of IVF in women with polycystic ovary syndrome (PCOS). The study was conducted on 323 women who did not take any OC and only waited for their spontaneous menses, and on 902 women who were prescribed to take OCs to induce their menses before starting the ovary stimulation stage of the IVF cycle.
This study demonstrated that among women who underwent fresh embryo transfer, pregnancy and live birth rates were lower among those who took OCs (48.8% and 36.1%) compared to those who had spontaneous menses (63.6% and 48.1%).
As for the subjects who underwent frozen embryo transfer (FET), pregnancy rates were similar between the two groups. However, a higher rate of pregnancy loss was found among those who used OCs (27.7%) compared to those who did not (13%). Live birth rate in the group with OC-induced menses was likewise lower than women with spontaneous menses (49.4% vs. 60.2%).
Restrictions on the Use of Birth Control Pills
Although the use of OCs can benefit an IVF cycle, it is not advised for some patients due to the following reasons:
- Can cause blood clots
Normally, the risk of developing an unwanted blood clot in women using OCs is extremely low – only around 0.1%. However, the risk significantly increases for women with a history of thrombosis (blood clot in the blood vessels).
If the patient had an incident of thrombosis in the past, the doctor may prescribe medications other than OCs to prepare the ovaries for stimulation.
- Growth of existing cysts
OCs can help prevent the development and recurrence of ovarian cysts. However, it can neither inhibit the growth of existing cysts nor shrink them. At worst, OCs may even cause the existing cysts to grow in size, preventing the follicles from maturing and producing healthy eggs.
- May reduce the oocyte yield
Women with low ovarian reserves are discouraged from taking OCs prior to an IVF cycle. A 2013 study by Barad, et al. found that exposure to high androgenic OCs suppressed women’s functional ovarian reserve and lowered their oocyte (immature egg cell) yields. Thus, a smaller number of mature eggs were retrieved from them for the IVF procedure.
- Unsuccessful previous IVF cycle
If the patient had an unsuccessful IVF cycle with OCs before, the fertility specialist might not advise its use on the next cycle. Instead, another ovary-stimulating medication may be recommended to improve the results of the IVF cycle.
Taking oral contraceptives (birth control pills) prior to an IVF cycle provides a number of benefits, including increased egg production and more controlled cycle scheduling. Unfortunately, it is not safe for all patients, so it is essential to talk to a fertility specialist about this beforehand. In terms of success rate, a few studies showed that IVF without OCs can lead to higher chances of resulting in pregnancy and live birth. However, the difference is minimal, so it is not considered a major factor that affects the success of an IVF cycle.