In a recent survey of over 500 “millennial” women (women ages 22–35), 60% of respondents indicated they were using some type of consistent birth control. It makes sense, then, that “What if I’m on birth control?” is one of the top questions we field from women who are thinking about freezing their eggs. Here, we’ll go over the relationship between birth control and fertility, and what women who want to freeze their eggs need to know about birth control.
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First—a quick overview on how the different types of birth control work.
We’re talking here about medical birth control options—not barrier methods like condoms or diaphragms, or natural methods like fertility awareness (the “rhythm” method).
Hormonal birth control
Hormonal contraceptives prevent pregnancy in a few ways. Most importantly, the hormones (either synthetic progesterone or a combination of synthetic progesterone and synthetic estrogen) prevent ovulation, the process by which an egg matures, leaves the ovaries, and enters the fallopian tubes for fertilization. No ovulation? No egg to be fertilized—meaning no pregnancy. The hormones also thicken the cervical mucus, preventing sperm from entering the fallopian tubes in the first place, and change the lining of the uterus to discourage an embryo from implanting there.
Hormonal birth control comes in a few forms. The most common is birth control pills (also known as oral contraceptives or OCPs), but there’s also the ring, the patch, the shot, and the hormonal IUD (more on those later). Each form has its own benefits, side effects, and effectiveness, but generally speaking, hormonal birth control is very effective, and may have benefits for women with hormone imbalances or conditions like endometriosis or PCOS (polycystic ovary syndrome).
Intrauterine devices (IUDs)
There are two types of IUDs. The first is a hormonal IUD; it uses a similar synthetic hormone to that used in birth control pills, released in very small amounts every day, to thicken cervical mucus and thin the lining of the uterus. The second is a copper IUD; the copper creates an environment in the uterus that’s toxic to sperm. The copper IUD doesn’t use any hormones.
Both copper and hormonal IUDs are “T”-shaped devices that are inserted into the uterus through the cervix (hence IntraUterine Device). IUDs are also extremely effective long-term birth control solutions—less than 1% of women using an IUD will get pregnant each year.
Birth control doesn’t affect fertility long-term.
Some women think that long-term hormonal birth control use could “mess up” their fertility; others believe that because they’re not ovulating while they’re on birth control pills, patches, rings, or shots, their egg supply will be better than it would be, otherwise. In reality, neither is true—birth control doesn’t have a long-term effect on fertility.
Women who were previously on hormonal birth control get pregnant at the same rates as other women their age.
“Within two to three months of stopping birth control, the medication fully metabolizes and clears out of the system. It should have no effect on women’s reproductive health,” explains Dr. Joshua Klein, medical director here at Extend Fertility. (The only exception to this is the birth control shot, which is intended to be a longer-acting form of birth control and might take longer to “wear off.”)
A study of almost 9,000 planned pregnancies published in 2002 determined that, while 85% of women who never used oral contraception had conceived within a year of trying, 89% of women who had used birth control for more than 5 years conceived within the same period. (The average age of the women in this study was 28 years old.)
The process of egg aging and loss that affects fertility continues, even if you’re on birth control.
Fertility declines in two ways as we get older. First of all, we have fewer eggs; secondly, the eggs we do have are more likely to be genetically abnormal, thanks to the inevitable damaging forces of everyday life.
The one egg (typically) that’s ovulated every month is not the only egg we lose—it’s just the single egg that makes it through the whole ovulatory process. The fact is that, each cycle, maybe 15–20 follicles are activated, but when they don’t mature, they get “reabsorbed” (AKA, they die). This process is called “atresia.” Plus, doctors estimate that we lose up to a thousand additional follicles each month, thanks to natural cell death. Atresia and cell death continue even if you’re pregnant, on birth control, or otherwise not ovulating.
Additionally, an egg is a type of cell, and like all living things, cells age. As eggs age, they’re more likely to contain what are called “chromosomal defects,” or problematic changes to the genetic material that tells the cell how to function. That’s why older eggs have a harder time doing what they’re supposed to do (make a baby). This, too, continues to happen, even while a woman is on birth control, pregnant, or otherwise not ovulating.
Long story short? Birth control won’t affect your fertility in the long run—for the worse or for the better.
Studies are unclear as to whether or not birth control can affect the results of fertility tests.
One of the best tests doctors have to estimate a woman’s egg count is to measure her AMH, or anti-Mullerian hormone, level. AMH is a protein hormone produced by special cells inside the ovarian follicles. The level of AMH in the blood can help doctors estimate the total number of follicles inside the ovaries, and therefore a woman’s total egg count. A typical AMH level for a fertile woman is 1.0–4.0 ng/ml, but, depending on age, many women will be higher or lower than this range.
Studies have attempted to determine the effect of hormonal birth control on AMH levels, but it’s still unclear. While several studies (1, 2, 3) have concluded that use of birth control doesn’t suppress AMH, others have concluded the opposite (1, 2, 3). The best answer doctors can give right now is that birth control may decrease AMH levels, temporarily, a bit—and this effect might depend on the person or even the type or brand of birth control they’re using.
“We don’t routinely recommend going off the Pill before AMH testing,” Dr. Klein explains. “But for women whose levels come in surprisingly low for their age who are on OCPs, we suggest stopping for 1–2 months and then re-testing.”
But again—even if birth control does affect AMH levels, it’s only temporarily. There’s no long-term impact on fertility as a result of taking birth control for years, or even decades.
We don’t require you to take birth control pills prior to your egg freezing cycle.
Some clinics require women to use birth control pills (OCPs) prior to their in vitro fertilization or egg freezing cycle. Why? OCPs allow doctors, or the patients themselves, to manipulate the timing of their cycle to better fit into a clinic’s, or the patient’s, schedule.
However, several studies have concluded that OCP use directly prior to a “stimulation” cycle (such as egg freezing) can result in a longer egg freezing cycle that requires more medication—and can actually negatively affect the number of eggs that are eventually retrieved. And since egg freezing success rates are based on two factors, the age the woman is at the time she freezes and how many eggs she freezes, a lower number of eggs retrieved can mean lower success rates later on.
“We don’t routinely use OCPs at Extend Fertility because of the potential suppressive effects,” Dr. Klein explains. We don’t require all of our patients to be on the same cycle, and unless the patient specifically requests a particular cycle date, we follow our patients’ natural cycles. “Since it isn’t in most patients’ ultimate best interests, we don’t do it,” says Dr. Klein.
Can you stay on birth control during egg freezing?
That depends on which type you use.
If you’re on hormonal birth control, you’ll need to stop during your egg freezing cycle.
The medications used during your egg freezing cycle prompt your ovaries to produce multiple eggs during one menstrual cycle, instead of the one egg typically matured and ovulated. Because hormonal birth control is intended to prevent ovulation, you can imagine that it’s not exactly what you should be taking during your egg freezing cycle. If you decide to freeze your eggs, you’ll stop taking all hormonal birth control—the pill, the patch, whatever—for the 8–14 days of your egg freezing cycle.
No matter which type of hormonal birth control you use, it can be resumed immediately following your egg retrieval.
The copper IUD can stay!
Because the copper IUD (ParaGard) doesn’t use hormones to prevent pregnancy, it doesn’t need to be removed before egg freezing—it can stay in place throughout the process. And because the egg retrieval is performed via a needle that goes through the wall of the vagina, there’s no chance of the IUD getting in the way.
Unprotected intercourse is a no-no during your egg freezing cycle.
Like we mentioned above, during egg freezing, the stimulation medication used to kick the ovaries into overdrive results in the production of multiple eggs, as opposed to the single egg usually produced during a menstrual cycle.
Barrier methods are a must during the egg freezing cycle.
While egg freezing cycles are very carefully timed, using a trigger shot to prompt the ovaries to “release” the eggs at just the right time for the retrieval, there’s always a small chance that the procedure might leave behind an egg or two. As you might remember from biology class, egg + sperm = possible pregnancy. And since the whole reason you’re freezing your eggs in the first place is because you’re not ready to have a baby (or multiple) right now, non-hormonal (barrier method) contraception is key!