Obesity Subtypes and Risk of Spontaneous versus Medically Indicated Preterm Births in Singletons and Twins.

Using data from the Missouri maternally linked files (1989–1997), the authors examined the association among maternal obesity, obesity subtypes, and spontaneous and medically indicated preterm (ptrend ptrend < 0.01). For extreme obesity, the risk of medically indicated preterm and very preterm births was almost double that for nonobese women. Similar findings were observed in twins. These data suggest that obesity increases the risk for medically indicated but not spontaneous preterm birth in both singletons and twins. [ABSTRACT FROM AUTHOR]