Study Finds Planned Delivery before 39 Weeks Harmful to Children

by | Nov 29, 2016 | Improving Birth

The American Academy of Pediatrics (AAP) issued a press release highlighting a study finding that planned cesarean or induction before 39 completed weeks increases the odds of developmental deficits at school age. Let’s look at the study in more detail, but let’s look too at the medical-model assumptions hidden between the lines and compare them with those of the physiologic care approach.

Starting with the study, Australian investigators linked medical records for 153,730 births with developmental assessment made during the first year of school at age 4-6. Developmental assessment included evaluation of language and cognitive skills, basic literacy, basic numeracy, physical health and wellbeing, and gross and fine motor skills. Children who scored in the bottom 10% in 2 or more categories were considered “developmentally high risk” (DHR). Investigators analyzed the relationships between gestational age at delivery and mode of birth with being DHR. Modes of birth were:

  • labor began on its own, vaginal birth
  • labor began on its own, cesarean delivery
  • labor induced, vaginal birth
  • labor induced, cesarean delivery
  • prelabor cesarean delivery

Using 40 completed weeks as the comparison, investigators found that after adjusting for factors associated both with mode of birth and developmental deficits, delivery at 37 or 38 weeks increased the risk of the child being DHR but the gap closed by 39 completed weeks. From this, they concluded that planned delivery should be delayed whenever possible until the “optimal time of birth at 39-40 weeks’ gestation” (p. 2).

Therein lies the rub. What the investigators don’t tell you is that outcomes at 41 or more weeks were identical to those at 40 weeks. They also emphasize the association between DHR and gestational age and glide over that the likelihood of the child being DHR was lowest at every gestational age when labor started on its own even when the labor ended in cesarean delivery and that the difference was marked for inductions that ended in cesareans compared with spontaneous labor onset ending in vaginal birth. Their spin (as does the take in the AAP press release) tells us they aren’t trying to establish a threshold past which the risks of a medically-indicated induction or planned cesarean would be minimized. They are advocating for an optimal window to deliver the baby. Period. And the reason why has to do with underlying medical management assumptions.

Chief among these assumptions is that women’s bodies are inherently untrustworthy. Even under the best of circumstances, something can go disastrously wrong at any moment. The best policy therefore becomes to rescue the baby at the earliest feasible moment. Contrast this with the physiologic care approach, whose proponents see themselves as guiding and guarding a process that will go right almost all of the time and that requires intervention only when complications arise because, “When nature does work, it cannot be improved. Technology does not enhance a natural process that is working. It can only mar or destroy it” (Stewart 1998, p. 71).

The medical-management approach confuses average with normal and enforces conformity to a standard to minimize perceived risks. Medical-model thinkers attempt to prevent harm to the few by taking actions without regard for the harm to the many in the process. In the case of elective induction, the justification is preventing stillbirth, an extremely rare event. A U.S. study found that stillbirth occurs at rates of 4 per 10,000 at 39 weeks rising to 8 per 10,000 at 42 or more weeks of continuing pregnancy in the population overall, which means that the rate would be still lower in women with no predisposing factors. The physiologic approach, on the other hand, acknowledges a wide range of normal for any physiologic process and applies the precautionary principle on the grounds that derailing a process proceeding normally inevitably has negative consequences.

Finally, as exemplified by this study, when medical-model thinkers conduct research, their conclusions are likely to confirm what they thought in the first place because their underlying beliefs influence what research questions they ask, what comparisons they make, what outcomes they consider important, how they interpret their results, and what implications they see. What is more, medical-model thinkers will ignore or discount studies that contradict their beliefs and commentaries pointing out flaws and weaknesses in studies aligning with them. Case in point: the only factor holding back proactive induction to prevent stillbirth was that research showed it increased cesareans—not that it was ever much of a deterrent. The new, and, I have argued, incorrect, understanding, though, is that recent studies have shown that induction doesn’t increase cesareans after all and may even decrease them. As a result, the thinking is rapidly becoming “Why wait?” once the woman reaches the 39-week mark.

These medical-model biases make this study both good and bad news. The good news is that it adds still another argument against early term delivery to the list. The bad news is that it backs up the group think that elective induction or cesarean after 39 weeks is just fine.

The Take-Away

As we have seen, the medical-management take-away from this study would be to induce labor or perform elective cesarean, that is, cesarean by choice, once women reach 39 completed weeks, but the physiologic care take-away would be:

  • Absent compelling medical reasons for ending the pregnancy ASAP, refuse planned delivery before the beginning of week 40.
  • With respect to induction, absent a medical reason to do otherwise, allow nature to take its course at least until 42 weeks.
  • Since induction is never an emergency, refuse rupture of membranes because if the induction doesn’t take, you can stop, go home, and try again another day.
  • Refuse elective cesarean.


Stewart D. The Five Standards for Safe Childbearing. 4th ed. Marble Hill, MO: NAPSAC; 1998.

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