Epidurals and occiput posterior babies.

Laboring mothers who have an epidural increase the chances by fourfold that their baby will be born in an occiput posterior (OP) position. A recent study examined baby position changes throughout labor and whether the use of an epidural leads to more malpresentation at birth. The study included 1,562 women and the results were published in the May 2005 issue of Obstetrics and Gynecology, the journal of the American College of Obstetricians and Gynecologists (ACOG).

To determine changes in the baby's head position during labor, ultrasounds were given when the mother was admitted to the hospital, at specific stages of labor and the baby's head position at birth was noted. According to this study, the position of the baby's head when the mother was admitted to the hospital did not establish the position of the baby's head at birth. In fact, only 31% of the babies who were in the OP position at the first ultrasound were still OP at birth.

Babies changing position throughout labor was common. 36% of the babies were occiput posterior at one point during labor. Even very close to birth, head position can change. Of the babies who were OP very late in labor, 80% of them changed position before being born. By comparison, 5.4% of occiput anterior (OA) babies changed position in late labor.

Women who asked for an epidural were not more likely to have an OP baby at the first ultrasounds, but they were more likely to have a baby in the OP position at birth. 12.9% of the women who had an epidural gave birth to OP babies. For women who did not have an epidural, only 3.3% of them gave birth to OP babies.

The study also evaluated if women with OP babies had more painful labors. Women with an OP baby at admission to the hospital did not report more painful or intense labors. 28% of women with OP babies reported "back labor", as did 29% of women with occiput transverse (OT) or OA babies.

For women with a baby in an abnormal position, there was a higher rate of cesareans, though not of instrumental delivery. The study concludes that epidurals are strongly associated with more OP babies at birth. This, in turn, leads to a higher rate of cesarean births and a lower rate of spontaneous vaginal birth compared to women who did not receive epidural anesthesia.

Obstetrics and Gynecology May 2005, Vol. 105, No. 5, pages 974-982. "Changes in Fetal Position During Labor and Their Association With Epidural Analgesia".