Recently, researchers reported that the most common length of a pregnancy in the United States has decreased from 40 to 39 weeks. Induction is one reason. "Some patients just do not want to wait for spontaneous labor to occur," says Carol Salerno, M.D., an OB-GYN at Northwest Hospital & Medical Center in Seattle. "But generally speaking, we would not do an elective induction prior to 39 weeks, the point at which we would anticipate fetal lung maturity. If there is a question that the fetus may be less than 39 weeks," Salerno adds, "we recommend an amniocentesis to check lung maturity prior to initiating an elective induction."
In cases of medical necessity, the decision to induce is often straightforward. But if a woman's cervix is not yet ripe--ready for labor--induction enters that "gray area" of concern to some physicians. A study of more than 41,000 births released this year by Sutter Health in Sacramento, Calif., showed "skyrocketing" C-section rates when elective inductions were performed on first-time mothers experiencing normal pregnancies or on those entering the hospital at the very start of their labor. The study indicated that risk for an unneeded C-section can be reduced if a woman is not admitted to the hospital until her cervix is at least 3 centimeters dilated.
Predicting a successful induction
The likelihood that induction will lead to a desired vaginal delivery depends on a set of five readiness indicators you may hear your doctor refer to as a Bishop score. Cervical dilation (opening), effacement (thinning), softness or firmness and position, as well as the position of the baby in the pelvis, are each given a number. With some exceptions, the higher the total, the more "inducible" the patient; the lower the total, the greater the risk of C-section, the need for delivery with the aid of instruments such as forceps or vacuum, or a prolonged rupture of the membranes that might lead to intrauterine infection.
"Nowadays, with the availability of cervical-ripening agents and other techniques, a Bishop score greater than 6 is highly associated with a successful induction leading to a vaginal delivery," Atlas says. "Still, women should be aware that inducing labor without a specific medical indication poses the risk of additional interventions in the event that a baby is simply not ready for labor to commence."
If you're considering induction, ask your doctor about the pros and cons. "Become as educated as you can about the process, and try not to become too attached to having a certain type of experience," says Atlas. (See "What to Expect When You're Inducing," next page.) "Some women appear to believe that induction is easy, and it is not," he adds. "An induced labor may take anywhere from several hours to several days. The more a woman knows about induction if she is considering requesting one, the more satisfied she is likely to be with her decision."