Induction of labor is on the rise in the U.S., standing at 41% according to a large national survey of women who gave birth in 2005. But, a new study published in the April issue of BJOG, the peer-reviewed journal of the Royal College of Obstetricians and Gynaecologists, finds that the best available evidence does not support many reasons medical providers give for using drugs or other measures to cause labor to begin.
The investigators found support only for inducing labor at or beyond 41 completed weeks of gestation and under some conditions when a woman's membranes break before labor. However, there is not good evidence for inducing labor in many other situations, including when the fetus is believed to be large or to have restricted growth, or when a woman is pregnant with twins, has insulin-dependent diabetes, or has low levels of amniotic fluid.
The study's lead author, Dr. Ellen Mozurkewich, a maternal-fetal medicine specialist at the University of Michigan, said, "The best available evidence does not support routine inductions in many situations for which induction is currently being recommended to patients. More research is necessary to clarify the risks and benefits of induction in these situations."
Many pregnant women may be receiving inappropriate care. For example, 17% of women who participated in Childbirth Connection's national Listening to Mothers II survey in 2005 said they had been induced because their caregiver was concerned that their baby was too big. However, best evidence suggests that labor induction is not beneficial in this case.
"We now know that every week of gestation counts in terms of brain and lung development. When there is no good reason to end pregnancy, mothers and babies benefit from waiting for labor to begin on its own," said Carol Sakala, Director of Programs, Childbirth Connection. "Starting labor early can lead to negative outcomes for the woman and/or baby."
To foster high quality maternity care, Childbirth Connection, a research and advocacy organization, commissioned this study through a grant from the Transforming Birth Fund of the New Hampshire Charitable Foundation.
Concerns about inducing labor without an established medical rationale include increased risk of cesarean section for some mothers (e.g., first-time mothers and women with a cervix that is firm and closed), and babies who are born before full lung and brain maturation. Estimates of how long a fetus has been developing can be off by up to two weeks, and labor induction can unwittingly end with a preterm birth.