SAN DIEGO – Although women who delay pregnancy to age 40 years and older face an increased risk for adverse outcomes, reducing prepregnancy body mass index may reduce their risk for cesarean delivery, gestational diabetes, gestational hypertension/preeclampsia, and preterm delivery, results from a large study demonstrated.
"This is an important issue in the United States as more than 13% of pregnant women are now age 35 and older, and nearly 3% are age 40 and older at delivery," Dr. John R. Barton said in an interview prior to a poster session at the annual meeting of the American College of Obstetricians and Gynecologists. "These data underscore the impact of obesity on increasing adverse outcomes in otherwise healthy women."
To examine pregnancy outcomes of healthy nulliparous women aged 40 years or older at delivery, Dr. Barton, director of maternal-fetal medicine at Central Baptist Hospital, Lexington, Ky., and his associates evaluated 53,480 women who were voluntarily enrolled in a pregnancy risk assessment and education program operated by Alere Health between July 1, 2006, and Aug. 1, 2011.
The researchers excluded women who reported heart disease, chronic hypertension, pregestational diabetes, other medical disorders, tobacco use, and conception with assistive reproductive technology. Data were grouped by maternal age (20-29 years or 40 and older) and obesity. Those with a prepregnancy body mass index (PPBMI) of 30 kg/m2 or higher were defined as obese; those with lower BMIs were defined a nonobese.
Within each PPBMI group, nulliparous women 40 years of age and older delivered at a significantly lower gestational age, had a greater incidence of cesarean delivery, gestational diabetes, preterm birth, and both low and very-low birth weight infants, compared with controls aged 20-29 years. In addition, obesity was associated with higher rates of adverse pregnancy outcomes in the group of women aged 40 years and older.
Dr. John R. Barton
"Throughout the reproductive years, health care providers to women should support and encourage them to maintain a healthy lifestyle and a healthy body habitus," Dr. Barton advised. "In healthy nulliparous women, both advanced maternal age and obesity influence pregnancy outcomes. Women choosing to delay pregnancy until age 40 years and older may modify their risk for cesarean delivery, gestational diabetes, gestational hypertension/preeclampsia, and preterm delivery by reducing their body mass index to nonobese levels prior to conception."
Dr. Barton acknowledged certain limitations of the study, including the fact that while the population included both Medicaid and commercially insured women from across the United States, "we do not know for sure if the same results would be observed in the general population or for those with later prenatal care initiation. It is also important to stress that these women were healthy in that they did not have heart disease, chronic hypertension, diabetes, or other medical disorders such as kidney disease or autoimmune disorders. We also did not include women that reported smoking during pregnancy. The overall rate of obesity was 17.7%, which is not comparable with the general obstetrical population (about 35%) – yet reflects our inclusion/exclusion criteria."
Dr. Barton disclosed that he has received research support from Alere San Diego, a subsidiary of Alere Health. Another study investigator, Dr. Baha M. Sibai, is a consultant for Alere San Diego.