By NICHOLAS BAKALARPublished: March 31, 2012

Women spend much more time in labor than they did 50 years ago, a new study has found, and one reason may be that obstetric practices have changed.

Scientists at the National Institute of Child Health and Human Development and elsewhere compared 39,491 births from 1959 to 1966 with 98,359 births from 2002 to 2008. All the women initially went into labor without complications.

Compared with the women in the first group, those in the more recent group were, on average, two and a half years older, the researchers found. They were also heavier — women giving birth in the later years had an average body mass index of 29.9, compared with 26.3 50 years ago.

Medical intervention was much more common in the 2002 group. Only 4 percent of women in the 1959 group received epidural anesthesia, compared with 55 percent in the recent group. About 12 percent of the women in the first group received oxytocin to induce labor, compared with 31 percent in the 2002 group.

The researchers also found that babies born in the later group were slightly bigger and healthier, with higher measures of overall health, called Apgar scores, at one and five minutes after birth.Click HERE to read more at The New York Times.