The difficulty of getting pregnant after age 40 is a common concern, especially as delayed childbearing becomes more prevalent. Biological changes accelerate significantly after 40, presenting a complex set of challenges for conception and pregnancy maintenance. Understanding the factual, science-backed realities of fertility after this age is important for family planning. This information helps set realistic expectations and informs decisions about the timing of medical intervention.
Understanding Conception Rates and Timelines
The probability of conception decreases substantially after a woman reaches age 40. A woman in her late 20s has approximately a 20% to 25% chance of conceiving naturally in a single menstrual cycle. For a 40-year-old woman, this chance drops to around 5% to 10% per cycle, falling further to approximately 1% to 2% by age 43.
This reduction in monthly probability means a longer time is required to achieve pregnancy. Within one year of trying, a woman under 30 has about an 86% chance of conception. A woman aged 40 has a cumulative chance of approximately 40% to 50% within the same timeframe.
For women under 35, infertility is typically defined as the inability to conceive after one year of regular, unprotected intercourse. For women over age 40, however, a fertility evaluation is recommended after only six months of trying, or even sooner. This accelerated timeline reflects the understanding that time is a more important factor when fertility is declining rapidly.
The Role of Ovarian Reserve and Egg Quality
The steep decline in conception rates is driven by two age-related factors: decreased ovarian reserve and degraded egg quality. A woman is born with a finite supply of eggs, known as the ovarian reserve, which is continually depleted throughout her life. By age 40, the remaining quantity of eggs is significantly lower than in earlier years, limiting conception opportunities.
Ovarian reserve is often measured using a blood test for Anti-Müllerian Hormone (AMH). Lower AMH levels indicate a diminished reserve, signaling fewer remaining eggs. This test predicts egg quantity, but the decline in egg quantity is a natural, irreversible process of reproductive aging.
Egg quality deteriorates sharply after age 40, which is often more impactful than the sheer number of eggs remaining. This decline is due to an increased rate of meiotic errors as the egg cells age. These errors cause aneuploidy, the presence of an incorrect number of chromosomes in the egg.
By age 40, nearly 60% of a woman’s eggs may be aneuploid, and this rate increases rapidly thereafter. Aneuploidy is the main reason for higher rates of early miscarriage and increased risk of chromosomal conditions, such as Down syndrome. Even if fertilization occurs, a chromosomally abnormal embryo is less likely to implant or result in a viable pregnancy.
Common Health Risks During Pregnancy After 40
A pregnancy after age 40 is generally categorized as high-risk, requiring closer monitoring due to increased potential for maternal and fetal complications. These risks are related to the effects of aging on the mother’s body and the genetic status of the embryo.
Maternal Risks
Maternal health risks are notably elevated for women in their 40s. There is a higher incidence of gestational hypertension, which can progress to preeclampsia, a serious condition involving high blood pressure and organ damage. The likelihood of developing gestational diabetes is also increased, sometimes more than double that of younger mothers. Furthermore, women over 40 have a significantly higher rate of requiring a Cesarean section delivery.
Fetal and Neonatal Risks
Fetal and neonatal risks also rise with advanced maternal age. The increase in aneuploidy leads to a substantially higher risk of miscarriage, with rates around 40% at age 40. Babies born to mothers over 40 are also at greater risk for outcomes such as preterm birth and low birth weight. These complications necessitate specialized prenatal care to manage potential health issues for the mother and the developing fetus.
Options in Assisted Reproductive Technology
For women facing conception challenges after age 40, Assisted Reproductive Technology (ART) offers pathways to parenthood. Due to the urgency of age-related fertility decline, specialists often recommend moving directly to advanced treatments.
In Vitro Fertilization (IVF) and PGT-A
IVF is the most common treatment for this age group, although success rates using a woman’s own eggs decrease significantly after 40. To address poor egg quality, Preimplantation Genetic Testing for Aneuploidy (PGT-A) is often used alongside IVF. PGT-A screens embryos for the correct number of chromosomes before transfer, selecting the most viable embryos.
Transferring a euploid embryo significantly increases the live birth rate per transfer and reduces the risk of miscarriage. However, the number of eggs retrieved and the percentage that result in a euploid embryo remain low at this age, often requiring multiple cycles.
Donor Eggs
When a woman is in her mid-40s or has had unsuccessful IVF cycles using her own eggs, the most successful option is the use of donor eggs. Donor eggs come from younger women, typically under 30, bypassing the issues of poor egg quality and low ovarian reserve. This dramatically improves the success rate, with live birth rates per transfer often reaching 50% or higher, comparable to success rates in much younger women using IVF.