Childbearing beyond maternal age 50 and fetal outcomes in the United States

Abstract

Objective: To estimate whether achieving pregnancy beyond maternal age of 50 years compromises fetal well-being and survival.

Methods: This was a retrospective study on all deliveries in the United States from 1997 to 1999. Four maternal age groups of 20-29 (young), 30-39 (mature), 40-49 (very mature), and 50 or more years (older) were constructed to assess risk gradients for fetal morbidity and mortality.

Results: A total of 539 deliveries among older mothers (aged 50 and above) were documented (four per 100,000). Among singleton gestations, the risks for low birth weight, preterm, and very preterm were tripled among older mothers, whereas the occurrence of very low birth weight, small size for gestational age, and fetal mortality were approximately doubled compared with those for young mothers. Older mothers also had greater risks for fetal morbidity and mortality than their immediate younger counterparts (40-49 year olds) except for very low birth weight. Among multiple gestations, the differences in risk between older and young mothers were lower than those noted among singletons. Still, compared with young mothers, older mothers had significantly higher risks of low birth weight, very low birth weight, very preterm, and small size for gestational age. Older mothers also had higher risk estimates for multiples than 40-49-year-old gravidas in terms of all fetal morbidity and mortality indices.

Conclusion: Pregnancy beyond age 50 was associated with increased risks for the fetus. Our findings suggest that this age group is a distinct obstetric high-risk entity that requires special counseling before and after conception.