MONDAY, April 24 (HealthDay News) -- The number of preterm births in Denmark has grown dramatically -- rising 22 percent between 1994 and 2004, according to a study published in the April 22 issue of BMJ.
Jens Langhoff-Roos, M.D., Ph.D., of the Rigshospitalet in Copenhagen, Denmark, and colleagues analyzed data on almost all of the deliveries in Denmark from 1995 to 2004 and measured the proportion of babies born at less than 37 weeks' gestation in the overall population and also in a standard population at low risk.
There was a 22 percent overall increase in the number of preterm births, during which time there was an increase in several know risk factors such as in vitro fertilization, multiple pregnancies and elective deliveries. Among women at low risk during their first pregnancies, spontaneous preterm deliveries rose 51 percent (from 3.8 percent to 5.7 percent), compared with a 20 percent rise for the general population (from 2.7 percent to 3.2 percent). The authors note that the contribution of stress on the rise in preterm deliveries remains unknown.
"Only primiparity and multiple births contributed substantially as explanatory factors of preterm delivery (17.7 percent and 14.3 percent)," the authors conclude. "Although in vitro fertilization is a strong risk factor for preterm delivery and contributes to the increase in multiple births, in vitro fertilization in itself contributed little to the overall risk."