There’s no single age where pregnancy becomes impossible, but fertility drops sharply after 40 and the risks climb steeply after 45. Most women reach menopause between 45 and 55, and fertility typically declines for several years before that final period. The practical answer depends on whether you’re conceiving naturally or using assisted reproduction, and how much medical risk you’re willing to accept.
How Fertility Declines by Decade
Women are born with all the eggs they’ll ever have, and both the number and quality of those eggs decline over time. By your mid-30s, that decline accelerates. A blood test called AMH can estimate how many eggs remain: the lower end of normal is about 1.5 ng/mL at age 35 and drops to around 1.0 ng/mL by 40. Below 1.0 is considered low, and below 0.4 is severely low.
But egg quantity is only part of the picture. Egg quality matters more for pregnancy outcomes, and it deteriorates in ways no blood test can measure. Older eggs are more likely to have chromosomal errors, which lead to failed implantation, miscarriage, or genetic conditions. This is why even women who still have regular periods in their early 40s often struggle to conceive.
Perimenopause, the transitional phase before menopause, can last several years. During this time, ovulation becomes unpredictable. You might still get a period but not release an egg, or release eggs only sporadically. By the time menopause arrives (defined as 12 months without a period), natural conception is no longer possible.
Miscarriage Risk Rises Dramatically After 40
The chance of miscarriage is one of the starkest age-related changes. At 35, about 1 in 5 pregnancies ends in miscarriage. At 40, that jumps to roughly 4 in 10. By 45, the miscarriage rate reaches about 80%, meaning only 2 in 10 pregnancies continue to viability. Most of these losses happen because of chromosomal abnormalities in the embryo, not because of anything the mother did or didn’t do.
The father’s age plays a role too. When men are over 40, the risk of miscarriage increases by about 23% compared to men in their late 20s. For men 45 and older, that risk jumps to 43% higher, even after adjusting for the mother’s age. First-trimester losses are particularly elevated with older fathers, with a 74% increased risk for men 45 and up.
Pregnancy Complications After 40
Even when a pregnancy sticks, older mothers face higher rates of serious complications. A large multicenter study comparing women over 40 to women aged 25 to 30 found significant differences across several categories.
Gestational diabetes affected about 2% of women in the younger reference group. For women 41 to 42, the rate was nearly 10%. By 43 to 44, it reached 11.4%, and it stayed at that level for women 45 to 46. Hypertensive disorders (including preeclampsia) followed a similar pattern: 1% in the reference group, rising to 4% at ages 41 to 42 and 6.2% at ages 45 to 46.
Cesarean delivery rates tell a parallel story. Among women 25 to 30, about 7% delivered by C-section. That tripled to nearly 20% for women 41 to 42 and climbed to 27% for women 45 to 46. These aren’t just numbers on a chart. A C-section means a longer recovery, a surgical scar that affects future pregnancies, and a higher chance of complications during the delivery itself.
Chromosomal Abnormalities by Age
The risk of Down syndrome and other chromosomal conditions rises exponentially with maternal age. At 35, the chance of a fetus having Down syndrome is approximately 1 in 272. At 40, it’s 1 in 65. At 45, it’s 1 in 27. By 50, it reaches roughly 1 in 19.
These are population-level estimates, not individual predictions. Prenatal screening and diagnostic testing (like cell-free DNA screening or amniocentesis) can detect most chromosomal abnormalities early in pregnancy. Many women over 35 choose these tests specifically because of the elevated baseline risk, and the results help inform decisions about the pregnancy.
Donor Eggs Change the Equation
If the main barrier to pregnancy after 40 is egg quality, donor eggs bypass that problem entirely. When women 45 and older use eggs from younger donors through IVF, the live birth rate per transfer cycle sits around 40%, which is comparable to success rates for younger women using their own eggs. Even women 50 and older see a cumulative live birth rate of about 54%, only slightly lower than the 58% rate for women 45 to 46, and that difference isn’t statistically significant.
This tells us something important: the uterus ages more gracefully than the ovaries. A healthy 48-year-old’s uterus can carry a pregnancy nearly as well as a 38-year-old’s, provided the embryo is chromosomally normal. The pregnancy complications of advanced age (gestational diabetes, hypertension) are still present, but the catastrophic miscarriage rates and chromosomal risks associated with older eggs largely disappear when using donor eggs.
What Fertility Clinics Actually Do
There is no universal age cutoff for fertility treatment. The American Society for Reproductive Medicine does not set a hard upper limit. Instead, it recommends that each clinic establish its own written policies about age-related inclusion and exclusion criteria. In practice, most clinics will discourage or decline IVF with a woman’s own eggs after 43 to 45, simply because success rates are extremely low. With donor eggs, many clinics will treat women into their late 40s or early 50s, provided they pass a medical screening for cardiovascular health, diabetes risk, and overall fitness for pregnancy.
The ASRM’s 2025 ethics opinion emphasizes that these age thresholds should be individually determined by programs and may shift over time as life expectancy and health outcomes evolve. The decision involves weighing not just the medical risks to the mother but also the well-being of the future child, including having a parent healthy enough to raise them.
The Practical Picture
If you’re in your late 30s and wondering whether you still have time, the short answer is yes, but the window is narrowing faster than it might feel. Fertility at 37 is meaningfully different from fertility at 42, and 42 is a different world from 45. The earlier you get a fertility workup (including an AMH test and an ultrasound to count follicles), the better you can plan.
If you’re over 40 and trying to conceive naturally, know that it may take significantly longer, and the chance of miscarriage is high even if you do conceive. IVF with your own eggs has limited success past 43. Donor eggs offer the most reliable path to pregnancy for women in their mid-to-late 40s, with success rates that hold up well into the early 50s.
If you’re over 45, natural conception is unlikely but not unheard of. The real question shifts from “can I get pregnant?” to “can I carry a healthy pregnancy safely?” The complications of gestational diabetes, preeclampsia, and cesarean delivery are real but manageable with close prenatal monitoring. Many women in their late 40s deliver healthy babies, particularly with donor eggs and attentive medical care.