A large new study, covering millions of U.S. births over 15 years, finds that substantial numbers of babies, nearly one in 25, are born earlier than medically justified, through elective cesarean sections and elective induced labor. The study reinforces long-standing recommendations by professional medical and public health organizations against early-term deliveries without appropriate medical reasons.
"A growing body of research suggests that health outcomes are worse for infants born before 40 weeks gestation, compared to full-term births," said Scott A. Lorch, M.D., M.S.C.E., a neonatologist at The Children's Hospital of Philadelphia (CHOP). "Unfortunately, many of these earlier births are 'nonindicated,' meaning there is not a medical rationale to deliver the baby early. We analyzed the extent to which these infants are born too soon and without medical indication."
The study appears in the July issue of Medical Care, published by the American Public Health Association. Lorch collaborated with lead author Katy B. Kozhimannil, Ph.D., MPA, of the University of Minnesota School of Public Health. "Our study showed that early elective deliveries are making up between 3 and 4 percent of U.S. births each year," said Kozhimannil. "This may seem to be a small number, but with 4 million births a year in the U.S., each percentage point represents 40,000 babies."
Unlike previous studies based in specific institutions and healthcare systems, the current analysis was a population-based study, covering all 7.3 million uncomplicated term births during 15 calendar years, 1995 to 2009, in three large states: California, Missouri and Pennsylvania. The retrospective study used hospital discharge data linked to state birth certificate records, and included mothers and infants from diverse socioeconomic backgrounds. In addition to representing distinct geographic regions, said Lorch, the three states account for approximately 20 percent of all U.S. births. The 15-year span allowed the researchers to discern trends over time.
Over the full period, the early-term nonindicated birth rate was 3.18 percent (232,139 deliveries out of 7,293,363 total uncomplicated births). The rate peaked in 2006, in which 4 percent of uncomplicated births to term infants occurred before 39 weeks' gestation without medical indication. By 2009, the risk of non-indicated birth before 39 weeks was 3.74 percent, 86 percent higher than in 1995, the start of the study period.
"Our study team found that nonindicated early births had adverse consequences for newborns and families," said Lorch. Early-term, nonindicated cesarean sections more than doubled the chance that a baby would have respiratory distress or need ventilation. Early-term nonindicated cesareans and early-term induced labor both lengthened the infant's hospital stay.
Further analysis revealed other patterns in the data. Mothers were more likely to experience early-term nonindicated births if they were older, had higher education levels, private health insurance, and if they delivered at a smaller-volume or a nonteaching hospital. Non-Hispanic black women were more likely to undergo nonindicated cesarean birth than non-Hispanic white women, but less likely to experience nonindicated labor induction.
Despite recommendations by professional organizations such as the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine, the study team showed that nonindicated early deliveries have continued to rise. Lorch suggests that further research should focus on the reasons for these procedures, with greater private and public health efforts to lower the rate of nonindicated early-term births.
"While prior research has shown that early elective delivery policies can be highly effective within particular healthcare systems, there is a need to address this issue at the population level," said Kozhimannil. "It is our hope that this study will add fuel to the ongoing efforts to educate pregnant women and influence clinical and policy environments to facilitate healthy, full-term deliveries whenever possible."
Funds from the Agency for Healthcare Research and Quality (grant RO1 HS018661) and the National Institutes of Health via the University of Minnesota's Building Interdisciplinary Research Careers in Women's Health Program (grant K12 HD055887) supported this study. In addition to Lorch and Kozhimannil, Michelle Macheras of CHOP co-authored the research.
Kozhimannil et al "Trends in Childbirth Before 39 Weeks' Gestation Without Medical Indication," Medical Care, July 2014.
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