What causes a baby to be posterior?
There is a rising incidence of posterior babies at the time of birth. We know now that epidural anesthesia increases the rate of posterior position at the time of birth from about 4% for women who don’t choose an epidural in a university birth setting up to about 13% when an epidural is used (Lieberman, 2005) Most babies who are posterior early in labor will rotate to anterior once labor gets going. Some babies rotate late in labor, even just before emerging. Studies, such as Lieberman’s, show that at any given phase of labor, another 20% posterior babies will rotate so that only a small number are still posterior as the head emerges. My observations are that the majority of babies are posterior before labor. The high numbers of posterior babies at the end of pregnancy and the early phase of labor is a change from what was seen in studies over ten years old. Perhaps this is from our cultural habits of sitting at desks, sitting in bucket seats (cars), and leaning back on the couch (slou
