Study Shows Fall in U.S. Birth Weights Because of Increase in Inductions, Cesarean Births

U.S. delivery weights have reduced considerably in recent decades as a result of rising rates of cesarean deliveries and inductions, which have contracted the average pregnancy by a few weeks, new CU Boulder research exhibits.

Previous analysis has shown that, after a long time of rising, birth weights started to fall in 1990, a pattern that has confused scientists and alarmed public health delegates effectively aware of the long-term antagonistic health results that may arise from low birth weight.

Lead author Andrea Tilstra, a Ph.D. aspirant in the Department of Sociology, set out to pinpoint what’s driving the trend, utilizing information from the National Vital Statistics System.

They analyzed over 23 million single births to healthy mothers from 1990 to 2013, utilizing demographic techniques to the plot: birthweight; week at which every birth occurred; and whether the child was born through vaginal delivery or cesarean delivery.

Then they conducted a simulation to see what would have taken place if cesarean and induction rates hadn’t elevated.

Among the examine inhabitants, the incidence of cesarean deliveries grew from 25% in 1990 to 31.2% in 2013, with rates rising quickest among healthy women in weeks 37 to 39.

In the meantime, the average size of pregnancy declined from 40 weeks to 39 weeks, and overall births became more and more concentrated between 37 and 39 weeks.

Nearly 18% of births in 2013 would have happened later, through a vaginal delivery that was not induced, had they occurred in 1990.