Kids who get too early a start at life – even if they are born in the first half of the gestation period associated with "normal term" birth – appear more likely to struggle at reading and math by the time they reach third grade, new research suggests.
In a study published Monday in the journal Pediatrics, researchers aimed to find out whether there were differences in third grade reading and math scores among nearly 130,000 children considered to have been born within a "normal" gestational range between 37 and 41 weeks.
What they found was that those born at 37 weeks and 38 weeks had significantly lower reading scores compared to children born at 39, 40 or 41 weeks. Math scores were also lower for children born at 37 or 38 weeks.
Lead study author Dr. Kimberly Noble, assistant professor of pediatrics at Columbia University Medical Center and New York-Presbyterian Hospital, said the findings should give parents-to-be pause before opting for early birth for non-medical reasons.
"The evidence from this study would suggest that elective induction of birth should be approached cautiously," Noble said. "The data suggest that children born at 37 or 38 weeks may have problems with reduced school achievement later on."
Noble said that even after taking a number of other factors into account – among them birth weight, socioeconomic background and maternal education – the link between earlier birth and academic performance was still evident. She added that, while it was possible that some other unmeasured factor could be responsible for the connection, "until we have more data we would encourage parents and physicians to exercise caution when considering elective induction of birth prior to 39 weeks gestation."
The study is the latest addition to a growing body of evidence that purely elective induction of birth may be a bad idea. According to statistics from the U.S. Centers for Disease Control and Prevention, such births appear to be a growing trend. Only 9.5 percent of all births in 1990 were through elective induction. Compare that to 2007, which saw nearly 23 percent of all births electively induced.
Efforts by many hospitals to encourage full-term pregnancies appear to have blunted this trend in recent years.
"The thing to keep in mind is that a child born 36 weeks, 6 days has brain size two-thirds that of a term infant," said Dr. Bryan Williams, associate professor of family and preventative medicine at Emory University School of Medicine in Atlanta. "They're still at a deficit with regard to brain development."
Williams and his colleagues have done their own research in which they compared the academic performance of more than 300,000 children in Georgia to their pre-term or post-term birth status.
"We found similar results, and arguably even greater relationships between test failure and gestational age," he said. "We, in fact, found kids at lower gestational age, who were extremely premature, were 250 percent more likely to fail a math test."
Still, for women approaching the end of their pregnancy, the draw of elective induction is hard to ignore.
"Pregnancy can be a trying time for many women, and the physical and emotional demands can seem exhausting, particularly by the end of the third trimester," said Dr. Sudeepta Varma, clinical assistant professor of psychiatry at New York University's Langone School of Medicine. "Many full-term women ask their obstetricians to help bring on labor sometime sooner than the estimated due date -- some may ask for elective C-sections, induction of labor, or attempt naturopathic methods at home.
"This study is so crucial in reminding pregnant women and their doctors to hang in there and allow nature take its course."
Additionally, many may not be aware of what constitutes an ideal gestation period. In 2006, a team of researchers surveyed women to determine their perceptions of the earliest point in pregnancy at which it is safe to deliver a baby. More than half of the women who responded considered 34-36 weeks of gestation to be safe, and more than 40 percent chose 37-38 weeks of gestation. By contrast, the American Congress of Obstetricians and Gynecologists (ACOG) sets this lower limit at 39-40 weeks of gestation – a range chosen by only 7.6 percent of women surveyed.
ACOG is one of a number of national organizations that have launched efforts to discourage non-necessary induction of birth.
"There has been a huge push nationally to reduce early term births, mainly from March of Dimes, ACOG and the Society for Maternal Fetal Medicine," said Dr. George Macones, chair of the ACOG's Committee on Obstetric Practice at Washington University in St. Louis. "ACOG has been very consistent over the years that 'elective' deliveries -- either induction or caesarean -- should not occur until 39 weeks."
Dr. Michael Katz, medical director of the March of Dimes and the former chairman at department at Columbia from where the new study emerged, said while more research is needed to truly determine the impact of elective induction of birth, the study reveals a problem that his organization has strived to improve.
"The trend toward prematurity has been rising year by year, not just in U.S. but in rest of the world," Katz said. "Even if there were no studies, if one looks at the rise in elective procedures, it would seem illogical ... to trump the process that has its own time schedule.
"If you do something anti-evolutionary, you are begging for trouble."
Many doctors seem to have gotten the message.
"We have stopped doing planned c-sections before 39 completed weeks and the same for 'elective inductions,'" said Dr. John B. Coppes, medical director of the Mayo Clinic Health System in Austin, Minn. "This will just strengthen our case to promote this practice."
Dr. Jacques Moritz, director of gynecology at St. Luke's-Roosevelt Hospital in New York and an ABC News medical contributor, said he believes the new study will further encourage mothers-to-be and their physicians to avoid elective induction of birth.
"The major effect of this news is going to be to mothers wanting to be induced to be done with pregnancy," he said. "I will definitely bring up this point of brain development to discourage them from wanting induction."
Still, ACOG's Macones noted that he worries the study may also cause concern in women for whom early delivery is necessary.
"In my opinion, the pendulum may have swung too far and now we have to find the right balance," he said. "I think this reinforces the concept that elective -- I stress the word elective here -- deliveries should happen after 39 weeks. That is the take-home message."
To this point, study author Noble and other physicians said the research should not be interpreted to mean that an early birth is a guarantee of cognitive problems. Coppes, for one, said he is living proof that an early start does not automatically predispose a child to irreversible cognitive issues.
"I was born at 36 weeks and weighed five and a half pounds," he said. "I have gotten through college, medical school, graduate school and work for 40-plus years despite my start in life. It is good to wait as long as possible to deliver, but not to scare too badly those who have to deliver early."