Children born in deliveries planned just a week before the end of a typical pregnancy may be more likely to experience health, learning and behavior issues by the time they're ready for school than kids born at full term, a study suggests.

Plenty of previous research has found premature infants often have difficulty breathing and digesting food. Some preemies also encounter longer-term challenges such as impaired vision, hearing, and cognitive skills as well as social and behavioral problems.

Pregnancy normally lasts about 40 weeks, and babies born after 37 weeks are considered full term.

In the current study, though, babies born in planned births at 37 weeks were 26 percent more likely to have developmental problems than infants born at 40 weeks. The increased risk for deliveries planned at 38 weeks was 13 percent.

Planned births might include labor inductions or surgical cesarean section deliveries.

"While the association between being born earlier (lower gestational age) and poorer developmental outcomes is well established, our results revealed that poor development is further exacerbated in the case of planned birth, where a considered decision made to deliver an infant determines gestational age," said lead study author Jason Bentley of the University of Sydney in New South Wales, Australia.

"Whenever possible planned birth should be at 39 weeks," Bentley added by email.

For the current study, researchers analyzed data on 153,730 infants born after at least 32 weeks gestation in New South Wales from 2002 to 2007.

Among births at 37 weeks, planned deliveries accounted for 48 percent of the cases. At 38 weeks, 55 percent of deliveries were planned births, researchers report in Pediatrics.

All of the children in the study had developmental assessments when they were around 5 years old.

Overall, 9.6 percent of the kids had developmental problems at school age, the study found.

Planned early birth was just one of the risk factors for this outcome. Development problems were also more common among boys, and among babies who were unusually small or born to mothers who were younger, poorer or smokers.

Even though births may be planned in some instances to address medical issues for mothers and babies, the findings suggest that it makes sense to delay these deliveries as late as possible in pregnancy, the authors conclude.

Labor inductions or cesarean deliveries that aren't for medical reasons shouldn't be scheduled before 39 or 40 weeks gestation, the researchers also conclude.

Limitations of the analysis include a lack of data on the reasons for planned deliveries, the authors note.

Even so, the findings add to a large and growing body of evidence supporting the delay of planned deliveries until as late as possible in pregnancy, Dr. Siobhan Dolan of Montefiore Medical Center in New York argues in an accompanying editorial.

"If you are having a healthy pregnancy, it is best to wait for labor to start on its own and if you are being induced or having a cesarean section — wait until at least 39 weeks," Dolan said by email.

"If you have a pregnancy complication - you may need to be delivered before 39 weeks - so talk to you doctor to understand the risks and benefits," Dolan added.

"There are circumstances where delivery before 39 weeks is the right decision — such as when the pregnancy is complicated by (severe high blood pressure) or placenta previa (when the cervix is blocked impeding delivery) and the risks of staying pregnant are greater than the risks of early birth," Dolan said. "But if your pregnancy is uncomplicated, wait until 39 weeks before having an induction or cesarean section."

Source: Reuters