First-time mothers during the early 2000s spent 2.6 hours longer in labor than did first-time mothers in the 1960s, according to an analysis funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
The researchers compared data from about 40 000 deliveries between 1959 and 1966 with data from 100 000 deliveries between 2002 and 2006 (Laughon SK et al. Am J Obstet Gynecol. doi: 10.1016/j.ajog.2012.03.003 [published online March 12, 2012]). Labor lasted on average 2 hours longer for women from the later cohort who had already delivered 1 child compared with the women in the earlier group. Infants born more recently were born 5 days earlier on average and were likely to weigh more.
Kuehn BM. Longer Labor. JAMA. 2012;307(20):2139. doi:10.1001/jama.2012.4796