SAN FRANCISCO, Feb. 5 Women who become pregnant in spring are more vulnerable to preterm birth than those who conceive in other seasons, according to researchers at the University of Pittsburgh. Results of a large study of such seasonal variation in preterm birth, or birth prior to 37 weeks gestation, are being presented at the 27th annual meeting of the Society of Maternal-Fetal Medicine, being held today through Saturday at the Hilton San Francisco and Towers in California.

"Preterm birth is a complex condition, and risk factors can change with the seasons," said Lisa Bodnar, Ph.D., M.P.H., R.D., assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health (GSPH) and a co-author of the study.

Preterm birth affects some 12 percent of pregnancies in the United States, costing an estimated $26 billion, or $52,000 per infant, in medical care and lost productivity in 2005, according to the Institute of Medicine. And a recent study from the U.S. Centers for Disease Control and Prevention found that preterm birth contributed to more than a third of infant deaths twice as many as previously thought and making it the leading cause of infant deaths yet the underlying causes of premature birth remain poorly understood.

More than 500,000 babies are born too soon each year nationwide, and the preterm birth rate has increased more than 30 percent since 1981. Babies who do survive face the risk of cerebral palsy, mental retardation, chronic lung disease, and vision and hearing loss, as well as other developmental problems.

Researchers analyzed data from 75,399 deliveries over a 10-year period at the university-affiliated Magee-Womens Hospital of UPMC, grouping each by season of "last menstrual period," a date physicians historically have used to estimate conception. Women conceiving in summer had the lowest rate of preterm birth at 8.4 percent, with steadily increased rates for the fall (8.8 pe
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Contact: Michele D. Baum
BaumMD@upmc.edu
412-647-3555
University of Pittsburgh Medical Center
5-Feb-2007