The 37th week of pregnancy traditionally marked the end of prematurity, suggesting the baby was fully prepared for life outside the womb. Modern research, however, provides a more nuanced understanding of fetal development during these final weeks. While delivery at 37 weeks is generally safe, every additional week in the womb contributes to a better outcome for the baby.
Understanding Early Term Status
The medical community has refined the classification of late pregnancy to better reflect neonatal health outcomes. Historically, any birth between 37 and 42 weeks was considered “term,” but this definition changed after studies showed that babies born earlier in this window faced higher risks of complications.
The current standard defines pregnancy timing using four precise categories. Delivery before 37 weeks is Preterm. The period from 37 weeks 0 days through 38 weeks 6 days is designated as Early Term. A baby is considered Full Term when born between 39 weeks 0 days and 40 weeks 6 days, which is the optimal window for delivery.
This terminology emphasizes that while a 37-week infant is not premature, it is not yet fully mature. The final weeks of pregnancy are periods of significant growth, especially for organs like the brain, which is still undergoing rapid development. The goal for a healthy pregnancy is to reach the Full Term stage before delivery.
Health Outcomes for Babies Born at 37 Weeks
Babies delivered at 37 weeks have statistically higher rates of short-term complications compared to those born at 39 weeks or later. A common issue is respiratory distress, particularly transient tachypnea of the newborn (TTN). TTN is characterized by rapid, shallow breathing due to excess fluid in the lungs, which occurs if the lungs have not fully matured.
Early term babies also face increased challenges regulating body temperature and maintaining stable blood sugar levels. The ability to coordinate sucking, swallowing, and breathing for feeding is sometimes less developed, which can slow their transition home. These factors contribute to a higher likelihood of admission to the Neonatal Intensive Care Unit (NICU) or specialized care nursery.
Beyond the immediate newborn period, studies note subtle, long-term differences in children born at 37 or 38 weeks. There is a small but measurable increase in the risk of certain neurodevelopmental differences, including cognitive problems and attention deficit hyperactivity disorder (ADHD), compared to those born at 39 to 40 weeks. These children may also have a slightly increased risk of respiratory problems like asthma or wheezing in early childhood. While the vast majority of 37-week babies are healthy, the evidence supports the concept that every week in utero before 39 weeks provides protection.
Clinical Reasons for Delivery at 37 Weeks
In some pregnancies, medical conditions mean the risks of staying pregnant outweigh the risks of an early term delivery. When a condition threatens the health of the mother or baby, the physician may recommend intervention at 37 weeks. This decision requires a careful balance of potential complications.
One common indication is preeclampsia, a blood pressure disorder of pregnancy. If a patient develops non-severe preeclampsia, the American College of Obstetricians and Gynecologists (ACOG) often recommends delivery at 37 weeks to prevent the condition from worsening. Placental issues, such as an uncomplicated placenta previa, where the placenta covers the cervix, may also necessitate delivery at this time to avoid severe bleeding.
Fetal concerns may also drive the decision for an early delivery. If ultrasound monitoring indicates significant growth restriction (estimated weight below the third percentile), delivery at 37 weeks may be recommended. Similarly, poorly controlled gestational diabetes or low amniotic fluid levels (oligohydramnios) can increase the risk of complications if the pregnancy continues. In these scenarios, removing the fetus from an unhealthy uterine environment is considered greater than the benefit of continued gestation.
Navigating the Decision to Deliver Early
When a medical indication for delivery at 37 weeks arises, open communication with the healthcare provider is essential. Expectant parents should ask specific questions about the risks associated with the mother’s condition compared to potential neonatal complications. The decision must be individualized, taking into account the specific diagnosis and the overall health of both mother and baby.
A provider may discuss the possibility of NICU time and the specialized support the hospital offers for early term infants, even if the baby appears healthy at birth. If a patient has a history of stillbirth, the psychological benefit of an earlier delivery to alleviate anxiety is sometimes weighed against the small increase in neonatal risks. Understanding that the timing of delivery is a thoughtful, risk-benefit analysis allows parents to participate fully in this shared decision-making process.