Why not induce everyone at 39 weeks?

In a debate presented at the 2016 annual meeting of the American College of Obstetricians and Gynecologists (ACOG), “If no elective inductions before 39 weeks, why not induce everyone at 39 weeks,” Dr Charles Joseph Lockwood, MD, MHCM, and Errol Raymond Norwitz, MD, PhD, weighed in on the subject with their respective points of view.

Also serving as the Edith Louise Potter Memorial Lecture, the debate took place on Monday, May 16^th, at the ACOG meeting.

Dr Lockwood commented to Contemporary OB/GYN on the feasibility and safety of induction at 39 weeks, noting that the background population rate of stillbirths climbs from 36 weeks to more than 42 weeks.

“Fetal macrosomia,” he explained, “also increases after 39 weeks, which can increase the infant’s risk of shoulder dystocia and the maternal risk of C-section. In addition, maternal complications like preeclampsia occur at 40 and 41 weeks. Thus, induction at 39 weeks could potentially reduce all of these risks, but the induction could be associated with a higher rate of C-section.”

Dr Lockwood also remarked that the current literature “is equivocal and not easily applied to the general OB population.” He noted that a clinical trial addressing these issues would need to include millions of patients.

At the debate, Dr Lockwood provided a Monte Carlo microsimulation model by USF researchers. He outlined it as follows:

·      Overall, when taking into account all outcomes and preferences, elective induction of labor during the 39^th week (eIOL-39) is always a superior decision strategy to the current practice of expectant management (EM) with IOL at the end of the 41^st week (EM with IOL-41).

·      Optimal maternal age for delivery is about 29 or 30 years.

·      In comparison to EM with IOL-41, eIOL-39 reduces number of cesarean deliveries, stillbirths, and severe complication rates for both infant and mother.

·      Neonatal and maternal mortality is not different between eIOL-39 and EM with IOL-41 strategy.

·      Maternal age, preferences for mother’s health versus baby’s health, and morbidity weighting did not meaningfully affect results.

Dr Norwitz commented to Contemporary OB/GYN that “My position is 39 weeks and Out!” He went on to explain further: “There is no benefit to the fetus waiting beyond 39 weeks in well-dated pregnancies. Continued EM is associated with risks to the fetus of stillbirth, neurodevelopmental injury, etc. If a baby is born at 39 weeks, it is not at risk of stillbirth at 40 weeks.” 

But what about the mother? Dr Norwitz responded that there is “no increased risk of cesarean in multiparas and nulliparas with a favorable cervix.” He concluded that “it probably does increase risk of cesarean for nulliparas with an unfavorable cervix, but given the newer cervical ripening agents, the risk is small.”

Both participants, Dr  Lockwood and Dr Norwitz, reviewed the literature on this topic.

Dr Lockwood is Dean of Morsani College of Medicine, University of South Florida, Tampa, and Senior Vice President of USF Health. Dr Norwitz is Louis E. Phaneuf Professor of Obstetrics & Gynecology, Tufts University School of Medicine, and Chairman, Department of Obstetrics & Gynecology at Tufts Medical Center, Boston, Massachusetts.