In the past, healthcare providers defined “term” to be the period of time from 37 to 42 weeks of pregnancy. This 5 week range was believed to be the healthiest time for a baby’s birth as most organs were thought to be adequately developed and functional; however, numerous studies over the last several years support a more narrowly demarcated range for “term” due to evidence that babies can experience different outcomes within that 5 week period.
As a result, the American College of Obstetricians and Gynecologists redefined “term” and created these 4 separate categories:
- Early Term: Between 37 weeks 0 days and 38 weeks 6 days
- Full Term: Between 39 weeks 0 days and 40 weeks 6 days
- Late Term: Between 41 weeks 0 days and 41 weeks 6 days
- Post-term: Between 42 weeks 0 days and beyond
Did you know that at 35 weeks, a baby’s brain weighs only two-thirds of what it will weigh at 39 – 40 weeks? Every week counts in fetal development. Unless there is a medical condition that necessitates an earlier delivery, babies are better off if they are born at full term. Babies born in early term can be at risk for jaundice, low birth weight, respiratory distress, and other conditions that are typically associated with premature babies and require medical intervention. For these reasons, organizations such as the March of Dimes and the Association of Women’s Health Obstetric and Neonatal Nursing developed campaigns to educate women and providers on the benefits of avoiding elective inductions and Cesareans; “elective” meaning these interventions are not medically necessary but performed due to the woman’s or provider’s choice.
For a low-risk pregnancy, this two week period is considered the optimal time for a baby to be born. All organs are fully developed and the placenta is typically healthy and functioning at full capacity. Babies born at full term have a lesser chance of experiencing negative outcomes; however, birthing a baby at full term is only half the picture. The method of delivery is an additional factor. Currently, one out of three women will deliver by Cesarean section in the United States. Cesarean involves the same risks as any surgical intervention (including risk of infection, bleeding, blood clots) and should be avoided unless medically necessary. The American College of Obstetricians and Gynecologists promotes Safe Prevention of the Primary Cesarean Delivery, or preventing cesareans for first time pregnancies in which there is one baby in a head down position at term. To avoid unnecessary cesareans, ACOG recommends redefining stalled labor, utilizing improved and standardized definitions for fetal heart rate assessment, and integrating non-medical interventions such as continuous labor support, among other suggestions.
Before defining a pregnancy as late term, your provider should confirm that the estimated due date is accurate. Because of an increased risk of stillbirth from 41 weeks on, ACOG states that special tests, known as antepartum fetal surveillance, “may be warranted” to assess the baby’s well-being. ACOG also notes that induction of labor between 41 weeks 0 days and 41 weeks 6 days “can be considered”.
During post term, there is evidence that risks for both baby and mother increase. In addition to the increased likelihood of stillbirth, there is also increased risk of forceps or vacuum delivery, cesarean delivery, shoulder dystocia, meconium aspiration, neonatal seizures, and low Apgar scores. Per ACOG, induction of labor after 42 weeks and 0 days and by 42 weeks and 6 days of gestation “is recommended”, due to this elevated risk.
As you can see, there’s a Goldilocks component to birth – best not to deliver too early or too late and full term is “just right”. You may begin to feel tired of being pregnant when you’re in the latter part of your third trimester. It may make sense on an emotional level that you want to meet your baby sooner rather than later but be aware of the potential consequences and let nature take its course. Early delivery is justified when there is a medical complication but, for low-risk pregnancies, remember what the March of Dimes promotes: “healthy babies are worth the wait”.