Natural birth

Women who attempted vaginal birth after cesarean were more likely to develop infections.

A new study conducted by the National Institute of Child Health and Human Development of the National Institutes of Health suggests that the risks from vaginal delivery after a prior Cesarean delivery are low, but are slightly higher than for a repeat Cesarean delivery.

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The study led by Catherine Spong enrolled 17,898 women at the 19 academic medical centers who were pregnant, and had a previous Cesarean delivery. They attempted a vaginal birth and 15,801 underwent an elective repeat Cesarean delivery. Women were classified as having an elective Cesarean if they did not have a medical indication (need) for it and if they did not have labor.

Of the women who attempted a vaginal birth after cesarean delivery, 124 experienced a rupture of the uterus. The study also found that using drugs to induce or speed up labor may also increase the chances for uterine rupture. Such drugs increase the force and duration of uterine contractions.

Of the 1864 women given the drug oxytocin alone, without any other drugs to induce labor, 20 had a uterine rupture. None of the 227 women receiving the drugs known as prostaglandins alone experienced uterine rupture.

Among the infants born to the women who attempted vaginal birth after a Cesarean, 12 were diagnosed with hypoxic ischemic encephalopathy, a condition that may result from lack of oxygen to the baby's brain. The lack of oxygen may be caused by heavy maternal bleeding, detachment of the placenta, or other complications.

Of these 12, seven were associated with a uterine rupture, and two of the babies died. In contrast, none of the infants whose mothers had an elective cesarean delivery developed hypoxic ischemic encephalopathy.

Women who attempted vaginal birth after cesarean were also more likely to develop infection of the uterine lining as compared to women who had an elective repeat Cesarean delivery. The study authors found no significant difference between the percentage of women who required a hysterectomy: 0.2 percent in the labor group and 0.3 percent in the C-section group. Similarly, there was no significant difference in the maternal death rate between the two groups of women (.02 percent versus .04 percent.)

Having a repeat cesarean delivery may complicate future pregnancies, sometimes causing the placenta to implant over the cervix, thereby interfering with the birth process. Prior Cesarean also increases the chances that the placenta will grow into the uterine wall, leading to difficulty with removal of the placenta after the birth. This may result in heavy bleeding during birth, perhaps leading to surgical removal of the uterus.