Babies Do Best When Arriving on Time

Late arriving babies just as likely as preemies to have behavioral and emotional problems

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Parents and docs know preemies come with a range of possible health risks, but what about the little bundles that arrive late instead of early? Turns out they have a few risks too.

A recent study has found that being born after 42 weeks of pregnancy is linked to attention deficit hyperactivity disorder (ADHD) and a higher number of behavioral and emotional problems in early childhood.

"Try to give birth at term - when your baby is due."

Lead author Hanan El Marroun, a researcher in the Department of Child and Adolescent Psychiatry and Psychology at Erasmus MC in the Netherlands, and colleagues conducted a study that is part of a larger Generation R Study that is following children from before birth into childhood and beyond.

A total of 5,145 pregnant mothers living in Rotterdam, the Netherlands, who would be giving birth between April 2002 and January 2006 joined the study through their midwives or gynecologists.

Using ultrasound scans to approximate the babies' gestational ages when the women enrolled, the researchers determined that 382 babies were born early and 226 were born late.

Then the parents were mailed a questionnaire to fill out when their child was 18 months old, and the again when the child was 3 years old.

In analyzing the data provided through these questionnaires, which used a standard child behavior checklist to assess them children, researchers found that children born preterm or post-term are at a greater risk for developing behavioral problems by 18 months old or 3 years old.

Children born after 42 weeks were approximately twice as likely as children born on time to have emotional and behavioral issues and were almost 2.5 times as likely to have symptoms on the ADHD scale.

The researchers also analyzed the data taking into account the mother's height, weight, ethnicity, family income, alcohol use, smoking status, education level and mental health during her pregnancy and found that the link between being born early or late and higher risk of behavior problems still held true.

However, the authors said there were still other factors that could have influenced this trend that they did not account for, such as the mother's nutrition during her pregnancy.

The researchers did not have a validated explanation for the association between early or late birth and the higher likelihood of emotional problems, but they proposed several hypothesis.

One educated guess was that an "old" placenta that is past the date it should have been used may not be providing sufficient oxygen or nutrients to the baby, but the researchers could not determine if there was evidence to support this idea.

They also suggested that perhaps the placenta has an internal clock which affected the baby's endocrine system when the pregnancy went longer than it was supposed to.

Another possibility they considered is that something happens during the birth itself that has an impact on the child's later neurodevelopment. Again, however, none of these theories had enough evidence to support it one way or the other and would require additional research and studies to confirm or rule out.

The authors also recommend continuing to study the children past their third year to see if the higher levels of emotional and behavioral problems continue to show up.

The study was published online May 2 in the International Journal of Epidemiology. The research was funded by the Sophia Children's Hospital Fund and the WH Kröger Foundation.

The Generation R study has been financially supported by the Erasmus Medical Centre, the Erasmus University and The Netherlands Organization for Health Research and Development. The only conflict of interest reported is that one author is the head of the Department of Child and Adolescent Psychiatry at Erasmus Medical Centre.

Reviewed by: 
Review Date: 
May 4, 2012
Last Updated:
October 4, 2012