Age & Fertility
It’s well documented that fertility declines with age—for both men and women. As men and women age, they produce fewer high-quality gametes (sperm in men, eggs in women). While hormones & biological processes differ between men and women, the end result can be the same.
At birth, the ovaries contain all the eggs a woman will ever have. By the onset of puberty, this number has already dropped into the hundreds of thousands. For most women, this means there are plenty of eggs to last from menarche to menopause. However, for women with low ovarian reserve or premature ovarian failure, supply is limited, and fertility declines much sooner. While there is no exact age at which a woman's fertility begins to diminish, population research has shown that, as a whole, female fertility starts to decline sharply around age 35. By age 40, a woman's chance of conceiving within one year is roughly half of what it was in her late 20s. With each passing year after 40, the chances of conceiving naturally continue to decline significantly, with women over the age of 44 having less than a 2% chance of conceiving using their own eggs.
Conception is not the only challenge that increases with age. Miscarriage rates rise sharply as women enter their 40s, increasing to 50% from about 10% for women in their 20s. Pregnancy complications also become more common, particularly conditions such as diabetes and heart disease. The risk of genetic abnormalities increases with age as well. At age 40, the chance of carrying a child with Down syndrome is about 1 in 100; by age 45, this risk rises to about 1 in 30.
While complications do increase for older women trying to conceive, pregnancy is not impossible, and many women in their 40s go on to have happy, healthy babies. It is important to remember that everyone ages at a different rate. The best way to determine your reproductive age is through ovarian reserve testing. If your ovarian reserve has already declined, there are several options to improve your chances of motherhood, including IVF, egg donation, gestational surrogacy, natural remedies like acupuncture and supplements, and adoption. For younger women postponing family planning, oocyte retrieval and preservation may significantly increase their chances of conceiving later in life.
Male fertility is also impacted by age. In addition to a decline in sexual function, male gamete production decreases over time. A 2006 study published in Fertility and Sterility (Killick et al.) found that, on average, men over 45 took five times longer to impregnate their female partners compared to men under 25. While men continue to produce sperm throughout their lives, both quality and quantity tend to decline with age, partially due to decreasing testosterone levels. Between the ages of 30 and 50, key sperm health parameters such as motility and morphology may decline by up to 50%. These measures are important because they indicate the genetic health of the sperm. Older men, with fewer healthy sperm, are not only less likely to help their partners conceive but also more likely to contribute to genetic abnormalities in the fetus. Research is still uncovering the extent of men's role in passing along genetic information, but new evidence suggests that younger male partners produce healthier offspring.
The bottom line: Even though men may remain fertile well into their 60s, decreasing conception rates and increasing genetic abnormalities can have a significant impact on fertility outcomes.