20s: Raring to reproduceIf mother nature were to choose the ideal decade for a woman to reproduce, this would be it. In your 20s, your risk of infertility, miscarriage, and health problems are at their lowest. According to the National Center for Health Statistics (NCHS), a 40-year-old woman is seven times more likely to have a baby with Down's syndrome than a woman in her 20s; for every 100,000 babies born to women in their 20s, 51 have Down's, according to the most recent numbers.
Women in their 20s also report more "maternal satisfaction," than women who are older. One reason for that may be that younger women often haven't finished college or started a career, so they don't have other roles that define them, observes Ramona T. Mercer, Ph.D., author of Becoming A Mother, and professor emeritus of maternity nursing at the University of California at San Francisco.
30s: Settled and self-assuredIf you're married and have established a career for yourself, this may be the decade that you decide you're also ready to tackle motherhood. While the vast majority of babies born to women in their 30s (and 40s) are healthy, there are some risks factors that increase during this decade. Women in their 30s are more likely to conceive babies with chromosomal abnormalities, and to experience pregnancy-related diabetes, eclampsia and hypertension, than younger women. And at 30 you're more likely to deliver via a Cesarean section than in your 20s. According to the NCHS, in 2000, 150 out of every 100,000 children born to women in their 30s had Down's Syndrome. If you're in your 30s (or 40s), you and your physician will have to decide if you want to undergo prenatal testing for chromosomal abnormalities.
On the positive side, if you're in your 30s, you're probably more self-assured than you were in your 20s, and may even be more enthusiastic about being pregnant. And you will have lots of company. Since 1980, the birth rate for women in their 30s has nearly doubled. According to the most recent statistics, the number of women having babies in their 30s rose by five percent; birth rates for this age group have increased steadily since the 1970s.