Episiotomies no longer are considered routine, Finan says, and finding a way to predict whether a woman will need the procedure would help obstetricians. But along with women's liberation, women began taking more responsibility for their health, and a push developed against an automatic episiotomy. Stretch marks, which develop in about 90 percent of pregnant women, according to the American Academy of Dermatology, begin in the skin's middle layer, called the dermis. That's an elastic layer consisting of fibers, known as collagen, which allow skin to snap back into shape. But when the dermis is stretched continuously over a long period of time, elasticity begins to weaken.
Lasers sometimes prove effective in erasing stretch marks.
Donofrio calls the Louisiana study interesting but wonders if there are other processes at work influencing tissue elasticity and episiotomies. During pregnancy, there are a lot of hormones that are released, like relaxin, which causes joints to be mobile and stretch. But whatever the cause, Donofrio agrees that stretch marks could be a predictor for vaginal lacerations during birth. What To Do For more on the effects of pregnancy on the skin, check out information provided by the American Academy of Dermatology . And to learn more about episiotomy, visit Childbirth.org .