Female fertility follows a well-documented decline with age, shaped by falling egg quantity and quality. This article explains what the population data shows at each decade, when to seek evaluation, and what IVF success rates look like across the reproductive lifespan.
Natural Conception Statistics by Age
In women under 30, approximately 25–30% of menstrual cycles result in pregnancy when timing is optimal and no underlying issues are present. This per-cycle probability, called fecundability, falls to roughly 15–20% in the early 30s, 10–12% by the late 30s, and under 5% by the mid-40s. The decline is gradual through the early 30s and then accelerates sharply from age 37 onward — a pattern driven largely by increasing rates of chromosomal abnormalities in eggs rather than a sudden loss of egg count. Cumulative conception rates over 12 months remain relatively high in the early 30s — approximately 80% for women aged 30–34 — because enough cycles occur in a year to compensate for the lower per-cycle rate. By age 40, however, the 12-month cumulative rate falls to roughly 40–50%, and by 43 to under 20%. These figures assume regular ovulation, normal uterine anatomy, and no significant male factor — a set of conditions that, taken together, represents about half of couples trying to conceive at any given age. The data is drawn from the CDC National Survey of Family Growth and large prospective European cohort studies, and represents population-level averages rather than predictions for any individual person.
When to Seek Fertility Evaluation
The American Society for Reproductive Medicine (ASRM) publishes age-specific timelines for when a couple should seek evaluation. For women under 35, the recommendation is to try for 12 months before consulting a reproductive specialist — a guideline grounded in the observation that most couples in this age group will conceive within a year. For women aged 35–39, the threshold drops to 6 months, reflecting the steeper age-related decline and the greater urgency of not losing additional time. For women 40 and older, ASRM recommends evaluation after just 3 months of trying, or immediately if there are known risk factors. Known risk factors that warrant earlier evaluation at any age include irregular or absent periods (suggesting ovulation problems), a history of pelvic inflammatory disease or endometriosis, prior chemotherapy or radiation, two or more prior miscarriages, and known or suspected tubal or uterine abnormalities. For the male partner, prior testicular injury, varicocele, or a history of sexually transmitted infections are reasons to order a semen analysis early rather than waiting. Prompt evaluation does not automatically lead to treatment — in many cases the workup is reassuring and the couple is advised to continue trying naturally. But identifying problems early preserves the widest range of treatment options.
IVF Success Rates by Age
IVF success rates vary significantly by age and are best understood from SART (Society for Assisted Reproductive Technology) national data, which the CDC publishes annually. Women under 35 using their own fresh embryos achieve live birth rates of approximately 45–50% per egg retrieval cycle. This falls to 32–38% at ages 35–37, to 20–25% at ages 38–40, to roughly 10–15% at age 41–42, and under 5% by age 43–44 using their own eggs. The primary driver of this decline is egg quality: as women age, a higher percentage of their eggs carry chromosomal abnormalities that prevent implantation or cause early miscarriage. Preimplantation Genetic Testing for Aneuploidy (PGT-A) screens embryos for these abnormalities before transfer, which can improve the per-transfer success rate by selecting chromosomally normal embryos — but it cannot increase the overall number of normal eggs retrieved. Donor egg cycles, which use eggs from a younger woman, essentially eliminate the age-related decline in success rates, achieving live birth rates of 55–65% regardless of the recipient's age. This makes donor eggs the most effective option when a woman's own egg quality is severely compromised by age or diminished ovarian reserve.