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- A person with a vagina’s peak fertility is when they’re in their 20s, though that doesn’t, of course, mean they can’t get pregnant later.
- Weight and lifestyle can affect fertility, but age is a more proven factor.
- Male fertility changes more slowly than female fertility.
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Whether you’re planning to start a family or just want to educate yourself about reproductive health, INSIDER unpacked how female (and male) fertility changes over time.
To find out how, we talked to Eric Forman, MD, HCLD, medical and laboratory director of the Columbia University Fertility Center. In addition, we consulted information from the American Society for Reproductive Medicine, a nonprofit, professional medical organization.
Here’s what you need to know about the ways in which your fertility fluctuates through the years.
People with ovaries are born with all of the ovarian follicles they will ever have.
They’re born with an estimated one to two million ovarian follicles or fluid-filled sacs that house immature eggs (oocytes).
The egg count reduces to about 300,000 by puberty. According to the American Society for Reproductive Medicine (ASRM), only 300 of these eggs will be ovulated during a woman’s reproductive years.
A person with a vagina’s peak fertility is when they’re in their 20s.
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“We tend to think that peak fertility is in the mid to late 20s,” Forman told INSIDER.
The ASRM, however, estimates that peak female fertility can range from the late teens through late 20s.
Factors such as weight and lifestyle can affect fertility, but age is more important.
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Forman said that while there is some association between infertility and lifestyle choices, such as excessive alcohol consumption and smoking, age is a more proven factor.
Upwards of 13% of female infertility is related to cigarette smoking, according to the ASRM, with 12% of cases pertaining to a woman weighing too much or too little.
By her 30s, a person with a vagina’s fertility gradually declines.
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Around age 30, women have a 20% chance of getting pregnant each cycle. The decline is more pronounced after age 35.
In your 40s, the odds of getting pregnant are much lower.
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By the time she reaches 40, a woman’s chances of getting pregnant each cycle could be as low as 5%, meaning fewer than five out of every 100 women are expected to be successful each month.
Fertility ends before menopause.
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On average, women have their final menstrual period at age 51. However, by the time they hit their mid-40s, the majority of women are not able to have a successful pregnancy.
It’s not just egg quantity that’s lowered over time.
Egg quality reduces, too.
Although research into egg quality is ongoing, the grade of an egg might depend on its ability to store gene products, such as messenger RNA (defined by Encyclopaedia Britannica as “the molecule in cells that carries codes from the DNA in the nucleus to the sites of protein synthesis in the cytoplasm”).
“As women get older, the chance of them releasing an egg that’s good quality or genetically normal is lower,” said Forman, explaining that, with age, there’s a higher likelihood of the egg dividing chromosomes incorrectly.
An egg is supposed to have 23 chromosomes (normal sperm have the same number). If there are additional or fewer chromosomes, an embryo will develop a genetic disorder such as Down syndrome.
A person’s “ovarian reserve” determines their reproductive potential.
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The overall quantity and quality of eggs in a person’s ovaries, known as the “ovarian reserve,” determine their reproductive potential.
Although it’s impossible to count the exact number of oocytes, several tests exist that indirectly measure ovarian reserve. For instance, doctors can gauge levels of anti-Müllerian hormone (AMH), which is produced by individual ovarian follicles.
When you should consult a fertility specialist depends on your age.
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Forman defines infertility as a year of attempting pregnancy through unprotected intercourse without successful results. For people over 35, it’s reasonable to consult a fertility specialist after trying to get pregnant for six months.
However, ovulatory dysfunction could also be a problem. If a person is not getting her period, they don’t have to wait as long for an evaluation, Forman said. According to the ASRM, irregular or abnormal ovulation accounts for 15% of female fertility issues.
If a person decides to proceed with fertility treatment, options range from drugs that help her ovulate or regulate hormone levels to in vitro fertilization (IVF).
Male fertility changes more slowly than female fertility.
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Like egg quality, sperm quality deteriorates over time – but at a much slower rate. Most people with penises do not experience a significant change in their fertility until they are in their 60s.
One study, however, concluded that men start to contribute to the reduced fertility of a couple in their late 30s, and to a reduced fecundity in their early 40s.
Although more research is needed on the subject, one study reported that higher paternal age has been correlated with a slightly increased risk of birth defects, some cancers, and schizophrenia.
Contrary to what you might think, infertility affects people with penises and people with vaginas almost equally.
In 40% of infertile heterosexual couples, the male partner is either the sole cause or at least partially responsible for infertility.
Men who are infertile have a few options depending on the cause, from surgery for a blocked vas deferens to hormone treatments.