By Alecia Eberhardt-Smith
Think back to high school sex ed (if you were lucky enough to get it). How much did you learn about fertility—about what happens when you actually want to get pregnant?
If you’re like most people, the answer is “nothing.” Here’s what you need to know about your fertility, even if you’re not planning a pregnancy any time soon.
You can only get pregnant a few days per month.
To explain, here’s a quick overview of an average menstrual cycle:
Days 1–5: Your period, the part of your cycle where your uterus is “clearing out” last month’s lining and unfertilized egg.
Days 6–11: The follicular phase. Your ovaries bring forth a group of eggs (housed in the ovarian follicles) for potential maturation. One egg will pull ahead of the pack to become the egg that’s ultimately matured and released.
Days 12–16: Ovulation, also known as the “fertile window.” The mature egg is released from the ovary and begins traveling down the fallopian tubes toward the uterus. For a pregnancy, sperm needs to be introduced either just before or during this 24-hour journey.
Days 17–28: The luteal phase. The empty follicle produces hormones that build up the lining in the uterus in preparation for a potential pregnancy. If the egg isn’t fertilized, the lining breaks down and the whole cycle begins again.
As you get older, your fertility decreases in two ways.
You’re born with all the eggs you’ll ever have. In fact, the egg that created you was in your mom’s ovary when she was a fetus inside your grandma. (Mind-blowing, right?!)
You start with around 1-2 million, and after puberty, you lose ~1,000 eggs per month. Menopause marks the point at which you’ve run out of eggs. Studies demonstrate that most people with ovaries have lost 80% of their eggs by age 30.
But more important than the number is the genetic health or “quality” of those eggs. As eggs age, they’re more likely to contain DNA errors that prevent fertilization or, in rarer cases, cause miscarriage or genetic disorders. According to one study, at 26, about 75% of your eggs are genetically normal; after 40, 30% or less of your eggs are normal.
If this sounds scary, it doesn’t have to. Fertility decline is inevitable, but that doesn’t mean it’s impossible to get pregnant after age 30 or 35—that’s obviously not true! It’s just important to know that as you get older, it can take longer to get pregnant naturally, and rates of infertility and miscarriage are higher.
Your period can give you a “heads up” about your fertility health.
The period is sometimes called the fifth vital sign, and for good reason—it can offer a lot of info about your fertility and your overall health.
For example, you may have symptoms of polycystic ovary syndrome (PCOS) or endometriosis. PCOS is a hormonal disorder in which your ovaries don’t release eggs regularly like they should, often leading to irregular, long, or absent periods. Endometriosis is an illness in which tissue similar to the lining of your uterus grows in other places in the abdomen, sometimes causing painful or heavy periods.
Both of these conditions impact your ability to get pregnant as well as your quality of life. Tracking your period with an app—or old-fashioned pen and paper—can give you helpful data to use when talking to your OB/GYN about your cycles.
Birth control doesn’t affect your fertility, but smoking does.
Good news for the 62% of people with ovaries that use hormonal contraception: even long-term birth control use doesn’t affect fertility. In a study of over 8,000 pregnancies, those who used oral contraceptives long-term had the same pregnancy rates as people their age who never used birth control.
Tobacco smoking, on the other hand, is one of the only lifestyle factors with good science to suggest it impacts fertility. The American Society for Reproductive Medicine reports that people with ovaries who smoke reach menopause 1 to 4 years earlier than those who don’t smoke. If you're a smoker, this is just one of a million good reasons to quit.
Preventing, testing for, and treating STIs can protect your fertility.
Untreated STIs, especially gonorrhea and chlamydia, can progress into a more widespread infection called pelvic inflammatory disease. Scarring from PID in the fallopian tubes can cause infertility even after the infection is cleared. To prevent this, use barrier protection like condoms, and get regularly tested and promptly treated for sexually transmitted infections.
You can gather info about your fertility way before you start “trying.”
Firstly, you can track your cycles. Secondly, you can ask the women in your family about their experiences trying to get pregnant (How long did it take? Did they experience any difficulties?), as well as the age they were when they went through menopause. Experts don’t know exactly how fertility is attached to your genes, but it’s clear that it is—you’re six times more likely to go through early menopause (that is, before age 40) if your mother, grandmother, or sister experienced it.
Lastly, you can try fertility hormone testing. There’s a battery of blood tests for estrogen, testosterone, thyroid hormones, and ovulation-related hormones that can indicate if something is out of whack—though these tests are typically only done if you already have symptoms of an issue, such as PCOS. Additionally, one of the most reliable and consistent fertility markers is anti-Mullerian hormone (AMH), which is produced by the follicles that house immature eggs in your ovaries. The higher the AMH level in your blood, the higher your egg reserve.
You can get these tests at your OB/GYN’s office, through a reproductive endocrinologist (fertility specialist), or via an at-home testing kit, if you feel brave enough to do a finger-prick blood draw.
The bottom line: there are things you can do now to understand—and protect—your fertility, even if kids aren’t in your plan any time soon.
Curious about pregnancy + birth?
Alecia Eberhardt-Smith is a writer and brand creative strategist specializing in reproductive health and fertility. She stumbled into the fertility space with a writing degree and a biology minor in 2011, and has been writing about—and studying—fertility medicine and its impact ever since. Learn more at aleciaeberhardtsmith.com.