Is There a Perfect Age for Pregnancy?

But what about the older mother-to-be's health? As women age, they may expect more challenges, including increased fatigue, more frequent medical conditions, and an increased risk of birth defects. However, the biggest challenge may be fertility.

Generally, at about age 32 or 33, a woman's fertility slowly begins to decrease. Some physicians believe that fertility decreases dramatically in a woman's mid to late thirties. "Fertility decreases with age," says Dr. Randy Morris, MD, from Chicago, Illinois. "This decrease is most likely due to aging of the eggs and the chromosomes inside them." This means that women are born with all the eggs they'll ever have—a 35-year-old woman has 35-year-old eggs.

Older moms may have to make more decisions about prenatal tests for birth defects, including amniocentesis, chorionic villus sampling, or high-resolution ultrasound. Michelle Byers, of Pittsburgh, Pennsylvania, remembers, "I felt confused and more nervous during my second pregnancy." Michelle had her first baby at 29 and her second at 34. "Each test my doctor offered made me more anxious about the health of my baby," she says. Women should inform themselves about all the options and make their own choices based on what is best for them and their babies.

The Risk of Birth Defects

The risk of giving birth to a child with a birth defect does increase as the mother's age increases. Approximately one in 1,400 babies born to women in their twenties has Down syndrome. "At age 40, your risks more than triple, leaving you with a 1 in 39 risk of a genetically unhealthy baby," writes Winkelman. "However, there is still a 97 percent chance that your baby will not have a chromosomal abnormality. Although your risks of chromosome problems are considerably 'higher' when you are 40 than when you are 35, they are not necessarily 'high' from an absolute point of view."

Age alone does not predict whether a pregnancy will be high risk. Several factors, such as family history, genetics, health, pre-existing conditions, and prenatal care of the mother also have major effects on the well-being of the mother and infant.

Women over 35 with a chronic disease such as hypertension or diabetes need to be monitored to ensure a safe pregnancy. Pregnant women over 35 tend to have a higher occurrence of gestational diabetes and preeclampsia (pregnancy-induced high blood pressure). "However, all pregnant women get tested for gestational diabetes at 28 weeks," says Dr. Rappaport.