As more women delay childbearing until later in life, it is important to understand the risk involved in waiting. Advanced maternal age generally refers to a woman who has reached age 35 by the date of delivery. The rate of births to women 35 and older has gradually increased, and in 2009, 14 percent of all babies were born to mothers 35 and older.
For most, the perceived risks outweigh the actual risk. An objective look at the risks of delivering after age 35 can be helpful.
One of the most common concerns for women in their 30s and 40s is whether they will be able to conceive. For most, the answer is yes. Studies show that fecundity — the rate at which a woman will conceive on the first attempted cycle — begins to slowly decline after age 32 through age 37. There is a more rapid decline from 37 to 45. Women 35 and older who want to conceive and have a history of irregular cycles, chronic pelvic pain or pelvic infections should have these problems evaluated by their health care provider before attempting pregnancy.
Aneuploidy, having an extra or missing chromosome or , can result in birth defects and developmental delay. The risk of Down syndrome, the most frequent chromosomal disorder seen in newborns, increases gradually with age. At 35, the risk is about one in 250 births. At 40, the risk increases to one in 50. If a woman delivers at 45, the risk is one in 10.
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Chronic medical conditions such as high blood pressure and diabetes are more common in women of advanced maternal age. Even women 35 and older who have been perfectly healthy are at increased risk of developing pregnancy-induced hypertension and diabetes. Developing either condition can result in additional visits to the health care provider for monitoring the mother and the baby, bed rest and need for pre-term delivery.
Caesarean section is more common in women 35 and older. Dysfunctional labor, complicating medical conditions and an increased rate of elective Caesarean deliveries all contribute to a higher cesarean section rate.
Pregnancy and delivery are never risk-free. The risks encountered by women 35 and older are relative to the baseline risk and must be seen in light of the socio economic benefits of delayed childbearing. Preconception consultation can individualize and potentially reduce the risks for women considering a pregnancy at any age.