Some women who have struggled with getting pregnant wonder if their past use of birth control might have caused their infertility. While there are assurances all over the internet that the birth control pill does not cause infertility, the answer is a bit more nuanced than that.
Let’s say you are 33 years old and got married a year ago. In the past ten years, you have been using a variety of hormonal birth control methods. Now you and your partner are looking forward to starting a family. You get off the pill, hopeful and a bit anxious as you know time is working against you—“biological clock,” and all. You try for eight months to get pregnant, but nothing happens.
You start getting concerned, and worry that your long-term use of birth control might have something to do with your fertility struggles. So you talk your doctor into putting you on Clomid, a drug known to stimulate ovulation, in the hopes that it might “jumpstart” your cycles once more. Unfortunately, this drug could actually lower your chances of conceiving, unbeknownst to you (more on this later). A few more unsuccessful months pass, before you get your first appointment at a fertility clinic. There you discuss your options: namely, Intrauterine Insemination (IUI) and In-Vitro Fertilization (IVF). You brace yourself for several months of treatment and thousands of dollars in medical bills, being assured all the while that this is likely your best hope for achieving pregnancy.
But could all the anxiety, doctor visits, and interventions be completely unnecessary?
When your cycles have returned after birth control, but you still can’t seem to get pregnant
Most women see their cycles return fairly quickly (i.e., the return of ovulation and menstruation) once a contraceptive device like the IUD, ring, patch, or implant is removed. And while most women see a return of their cycles fairly quickly after discontinuing birth control pill use, in some cases, it can take up to a year for your fertility to return as you begin to cycle regularly once again. A woman who has used the birth control shot Depo-Provera may not see a return to fertility for up to 18 months or longer.
Although birth control pills or devices may not cause long-term cycle-suppression after discontinuation, they can still delay your return to fertility, i.e., your ability to get pregnant. One theory for the delay in fertility post-birth control is the pill’s impact on the production of cervical fluid, an essential component of conception. Another theory is the possible association with long term (i.e., 5+ years or more of) contraceptive use and a significantly thinner endometrial lining. Because a thickened endometrial lining is essential for proper embryo implantation, a thinner lining can make it difficult to achieve pregnancy, even if ovulation and conception can still occur. No matter the cause, the delay in a return to fertility after being on birth control can be critical as women tend to start their families much later in life now than in earlier decades.
The importance of cervical mucus in fertility
We are all taught in high school biology or sex-ed that it takes a sperm and an egg to make pregnancy happen. What is often left out of this equation is the cervical fluid, also known as cervical mucus.
In order for sperm to survive more than a few hours in the vagina, and then have the energy reserves to travel through the uterus all the way to the fallopian tubes and wait for the egg to arrive, it needs good quality, fertile cervical mucus. Cervical mucus also does the important job of filtering out “bad” sperm, i.e., sperm with poor morphology or motility, to maximize your chances of having a healthy pregnancy and baby.
Cervical mucus is secreted by pockets in the cervix known as “crypts.” The mucus changes in consistency and appearance as ovulation approaches, in order to better nourish sperm and help it to reach the egg. Before and after ovulation, cervical mucus is much thicker, and blocks access to the uterus (a mechanism that also protects the womb from infection). At the time of ovulation, the cervical mucus becomes thinner and stretchier, almost like raw egg whites, allowing the “good” sperm to swim easily through the vagina and the cervix, into the uterus and fallopian tubes. Once there, the sperm await an egg for fertilization, and can actually survive for up to 5 days in the female reproductive tract in the presence of fertile-type mucus.
Without sufficient, good quality mucus, there can be no baby.
How birth control works to prevent pregnancy
Hormonal contraceptives, as generally documented in scientific literature, don’t work to prevent pregnancy just by suppressing ovulation (although this is generally the primary mechanism of action for the most popular forms of birth control, such as combination pills). Another mechanism by which contraception prevents pregnancy is its effect on the production of cervical mucus. Hormonal birth control actually continuously thickens cervical mucus, which provides an additional barrier against pregnancy in case ovulation still takes place (which can happen, although exactly how often is unknown).
If a woman is not taking hormonal birth control, the cervix follows the marching orders of your body’s naturally occurring hormones. But when a woman is on hormonal birth control , the synthetic hormones in the pill (or patch, ring, implant, or IUD) override the natural ones, and run the cervix in a way so that it constantly produces this non-fertile mucus. But how do the synthetic hormones in birth control accomplish this feat?
What does birth control do to your cervix—and your cervical mucus?
One theory of how of birth control effects cervical mucus comes from the research of a man named Erik Odeblad. Dr. Odeblad was a Swedish professor and researcher born in 1922, who spent most of his life studying and explaining the secretion of cervical mucus: specifically, the various types of mucus produced at different stages in a woman’s cycle and in her life, and their role and composition.
Dr. Odeblad was one of the first scientists to use MRI technology for a medical purpose, and through his research, Dr. Odeblad discovered that there are at least three different types of cervical mucus. Dr. Odeblad called the different types of cervical mucus G, L, and S, and found that each has a different role, and is secreted by a different kind of cervical crypt at different times in a woman’s cycle and during different times in her life.
Dr. Odeblad found that right after puberty, a young woman has an abundance of S crypts, and as she ages, the number of S crypts decreases; the S crypts are then replaced by L crypts. Dr. Odeblad discovered that S mucus (which is secreted by S crypts) in particular is the type of mucus that is essential to fertilization: it provides passage, transport, and nourishment of sperm.
Dr. Odeblad appeared to find that hormonal birth control actually diminishes the amount of S crypts a woman has. From his findings, Dr. Odeblad concluded that “for each year the Pill is taken, the cervix ages by an extra year.” He posited that long-term use of hormonal contraception may impair a woman’s chances of conceiving, because of the degradation of S crypts in her cervix.
Although Dr. Odeblad’s data has not been evaluated with a peer-reviewed study, his findings are not without precedent, as there is other evidence suggesting that hormonal birth control can have some effect on the tissues of the cervix. Further, long term use of oral contraceptives is also associated with increased cervical cancer risk, as well as accelerated maturation and increased cell proliferation of cervical epithelial tissue.
Why a delayed return to fertility after birth control matters
For a variety of reasons, women are waiting longer than ever to start their families than in the past. Case in point: in 1970, the average age at first child birth was 22. Today, it has risen to 26.4 years old. In addition, more women are delaying their first pregnancy past age 30. The percentage of first birth to women over 30 went from just one in ten in 1970, to almost one in three in 2014. This late start to childbearing is significant, because on average, a woman’s ability to get pregnant takes a sharp decline after age 35, and is practically nil by the time she reaches her mid-forties.
If a woman waits until her fertility is already in a natural state of age-related decline to try to get pregnant—and especially if she has been on birth control for several years prior, possibly depleting her S crypts and chronically thinning her endometrial lining—she may face even more obstacles to conceiving. If a woman’s issues with fertility lie in a problem with proper cervical mucus production, and she is placed on Clomid, it could further thwart her chances of conception: a known side effect of this drug is to reduce the production of cervical fluid.
Further complicating matters, many women begin hormonal contraception as a means to “regulate” irregular or painful periods. Often, an irregular period is a sign of an underlying health condition such as endometriosis, polycystic ovary syndrome (PCOS), or some other hormonal imbalance—all of which are associated with infertility. If a woman began taking birth control to reduce symptoms for one of these conditions, she is likely to still be faced with painful and irregular periods once she discontinues birth control—and may also have trouble conceiving as a result of them not being treated.
How truly restorative reproductive medicine is the solution for infertility—even before you experience it
That is why it is so important that teenagers and young women have access to information about what’s known in the medical community as Fertility Awareness-Based Methods, more informally called fertility awareness methods (FAM) or natural family planning (NFP). Doctors who are trained in restorative reproductive medicine such as Natural Procreative Technology (NaProTechnology), can address the root causes of painful or irregular periods. With the treatment provided by fertility awareness doctors, a woman can get true relief from her symptoms, while healing her fertility for whenever she is ready for pregnancy. When a woman is faced with infertility, a thorough evaluation of both her ovulations and of her mucus production is needed, which is something restorative reproductive medicine and NaPro can provide.
We find here yet another great reason why young women who are hoping to get pregnant one day should avoid hormonal birth control all together and opt for evidence-based methods of natural birth control, by learning to chart their cycles with a fertility awareness method. Not only will these methods preserve their fertility, but when the couple is ready to achieve a pregnancy, the knowledge gained through training in a FAM will help them reach that goal more quickly and easily.
To find a restorative reproductive health practitioner who can meet via telehealth, check out this resource.
When this article refers to fertility awareness methods (FAM), or natural family planning (NFP), we are referring to Fertility Awareness-Based Methods, evidence-based methods of cycle charting which can be used as effective forms of natural birth control when learned by a certified instructor.
This article was originally published on March 11, 2017 as written by Gerard Migeon. It has since been updated by Natural Womanhood to offer more resources. Last updated October 3, 2020.