A normal singleton human pregnancy has a gestational duration of 37 to 41 weeks. A pregnancy is considered full term when the 37 week mark is reached. It has been thought that babies born at 37 weeks had reached all of the same developmental milestones that babies born at 41 weeks had reached. Prematurity is a birth that occurs before the 37 week mark and can carry additional developmental and health risks associated with it.
Researchers from Columbia University Medical Center in New York City, lead by Dr. Kimberly Noble, have found that babies born just a few weeks before the 41 week mark can have more academic difficulties. The results of their study were published online in the journal Pediatrics. The researchers sought to examine the degree to which gestational age at birth effects reading and mathematical achievement in school.
The study analyzed data collected from over 128,000 full term singleton births occurring between 37 and 41 weeks in New York City. The investigators assessed birth timing and its effect on city-wide third grade standardized test scores in reading and mathematics. Children born at 37 weeks were 14% more likely to have mild reading difficulty and 19% more likely to have mild math difficulty, as compared to children born at 41 weeks. In addition, children born at 37 weeks were 23% more likely to have moderate reading difficulty and 19% more likely to have moderate math difficulty as compared to children born at 41 weeks. Finally, children born at 37 weeks were 33% more likely to have severe difficulty in reading. For all of the children born at 37 weeks, approximately 2.3% had severe difficulty in reading, compared to 1.8% of children born at 41 weeks.
The authors wrote, “Increased gestational age at birth has a positive association with third-grade reading and math scores among children born in the 37- to 41-week range, commonly defined as term gestation. From a public health perspective, this may have important consequences, particularly in the realm of identifying children who may be at risk for poorer school achievement… in light of the increasing trend for performing elective early deliveries for nonmedical reasons, researchers, clinicians, and parents are urged to consider this graded relationship between weeks of gestation and school performance”.
This study suggests that the fetal brain continues to develop even in the later weeks of pregnancy, and that development which occurs in utero is more advantageous for the newly born infant. Subtle neuro-cognitive developmental changes occur in late pregnancy that can make a difference in the academic achievement of children. Considering this new information, should we redefine what we consider a full term pregnancy? We probably should. After all, telling our patients that births that occur at 37 weeks are normal may not be entirely correct. As this study shows, there are subtle academic differences that can be detected as early as the third grade, and these differences may become even more evident as children grow older. At the least, we should recommend that all elective early cesarean deliveries be postponed to the 40 week mark so as to give the most in utero development time to the baby. Wouldn’t all mothers and fathers want to give their babies the best chance at better academic achievement?
Noble KG, et al. “Academic achievement varies with gestational age among children born at term” Pediatrics 2012; DOI: 10.1542/peds.2011-2157