The period of time for a pregnancy is called gestation. The full term of a pregnancy is about 39 weeks to 40 weeks, or just more than 9 months. An infant born before 37 weeks is considered preterm. Studies have shown that preterm birth is the most frequent cause of infant death and the leading cause of long-term neurological disabilities in children; the more preterm the greater the risk.
Among preterm infants, studies have shown that infants born later in pregnancy (approaching 37 weeks) tend to do better developmentally than infants born earlier. But, few studies exist have examined the development of “early term” infants (born at 37 weeks but before 39 weeks). Such information is critical given a recent rise in elective cesarean deliveries.
An opportunity to address this issue was provided as part of a study conducted in Chile. This research was designed to address interventions to prevent iron deficiency, and included a large group of healthy newborn infants.
In this analysis, researchers funded by the Pediatric Growth and Nutrition Branch were able to examine the window of time between 37 and 41 weeks to determine the relationship between gestational age and development scores in healthy infants. Infant development was assessed 12 months after birth. The study accounted for certain factors such as birth weight, gender, socioeconomic status, and iron status.
The researchers reported that for each additional week of gestation, development scores increased and concluded that infants born at 39 to 41 weeks had developmental advantages compared with those born at 37 to 38 weeks. The study findings are useful to inform medical practice and policy, and add to the growing evidence that allowing pregnancies to progress to full term whenever possible leads to better infant development outcomes (PMID: 23589812).