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Mark P. Trolice, M.D., FACOG, FACS
Milton McNichol, M.D, FACOG
Board Certified in Reproductive Endocrinology and Infertility
Childbearing After the Age of Fifty
As the trend to delay childbearing in our society increases and assisted reproduction technology makes it possible for even postmenopausal women to conceive, information about the outcomes of pregnancy in older women becomes increasingly important.
Only in 1997 did the National Center for Health Statistics begin recording the actual age of pregnant women aged 50 to 54 years. Salihu et al from the University of Alabama at Birmingham made use of these data to try to determine if there are specific and unique risks associated with pregnancies of these older women.
The authors grouped maternal age in years into 4 cohorts:
- 20 to 29 ("young mothers")
- 30 to 39 ("mature mothers")
- 40 to 49 ("very mature mothers")
- greater than/equal to 50 ("older mothers")
The main birth outcomes of interest were fetal mortality (intrauterine death at greater than/equal to 20 weeks' gestation), low and very low birth weight (less than 2500 g and less than 1500 g, respectively), preterm and very preterm delivery (less than 37 and less than 33 weeks' gestation, respectively) and small size for gestational age (less than 10th percentile of birth weight for gestational age). Maternal complications were also noted.
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about one third of all pregnancies among the older mothers were multiple, a rate 7 times that of the 40-year-olds.
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A total of 12,066,854 deliveries resulting in live births or fetal deaths was recorded in the United States from 1997 to 1999 inclusive; 539 (4/100,000) of these births were to women aged greater than/equal to 50 years. These women were much more likely to have had multiple gestations: about one third of all pregnancies among the older mothers were multiple, a rate 7 times that of the 40-year-olds. The overwhelming majority of the multiple births in all groups were twins.
As for maternal complications, cardiac disease, diabetes, chronic hypertension, placenta previa and abruptio placentae were positively associated with maternal age. In contrast, anemia showed a consistently negative relation with age, and both pre-eclampsia and eclampsia showed a nonlinear distribution. Fetal morbidity and mortality were analyzed separately for singleton and multiple pregnancies.
For singleton infants born to older mothers, the risks for low birth weight, preterm and very preterm delivery were 3 times those of singleton infants born to the young mothers; the occurrence of very low birth weight, small size for gestational age and fetal mortality was twice as likely among the older-mothers group.
Even when compared with the 40 to 49-year-olds, the older mothers had increased risks of fetal morbidity and mortality, although the former showed a slightly higher occurrence of very low birth weight. For the multiple pregnancies, the differences in fetal morbidity and mortality between the over-50 and young mothers groups were much smaller, but there were still significantly higher risk levels for low birth weight, very low birth weight, very preterm and small size for gestational age.
Conclusions and Clinical Implications
The study shows that the risks for adverse pregnancy-associated conditions increased from one advanced maternal age group to the next higher one and that the risk for adverse fetal outcomes for singleton births was higher among the older mothers.
While the relative risks for fetal outcomes among multiple births were higher among the mature and very mature mothers compared with young mothers, the magnitude of the differences was less than among singletons. In fact, the risks for fetal morbidity and mortality among multiple births of mature and very mature mothers were either lower than or comparable to those of young mothers. For the over-50 mothers, however, consistently higher risks for fetal morbidity and mortality were seen for both singleton and multiple births. The authors suggest that advanced-age mothers may represent a distinct obstetric entity, with a risk pattern different from that observed for mature and very mature mothers. Therefore, they see a need to provide older women with special counseling before and after conception to inform them of the risks involved.
Salihu HM, Shumpert MN, Slay M, et al. Childbearing beyond maternal age 50 and fetal outcomes in the United States. Obstet Gynecol 2003;102:1006-1114.
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