Babies born after 42 weeks 'at risk' of ADHD

Researchers from Erasmus MC-Sophia in Rotterdam, the Netherlands, looked at data from the Generation R study, a large population based prospective cohort study, following pregnant mothers in Rotterdam who were due to give birth between April 2002 and January 2006.

The study followed the progress of 5,145 babies. It was found that 382 babies (7 per cent) were born post-term, that is after 42 weeks, and 226 (4 per cent) were born pre-term.

They measured mothers' gestational age using ultrasound, and after birth assessed children’s behaviour using the Child Behaviour Checklist for toddlers, designed to measure children’s behavioural and emotional problems. Parents were also sent questionnaires when their child was 18 and 36-months-old.

The findings revealed that post-term babies, 42 weeks old, were almost twice as likely as term born children to have behavioural and emotional problems. Babies born after term and before term were also more likely to develop ADHD.

The researchers suggest a number of explanations for their findings, including the higher risk of problems associated with larger babies and an ‘old’ placenta offering fewer nutrients and oxygen which could lead to abnormal emotional and behavioural development.

Lead author Hanan El Marroun said, ‘Post-term children have a considerably higher risk of clinically relevant problem behaviour and are more than twice as likely as term born children to have clinical ADHD. Further research is needed in order to determine the causes of post-term birth and to minimise the long-term consequences.’

The study, ‘Post-term birth and the risk of behavioural and emotional problems in early childhood’, is published in the current issue of the International Journal of Epidemiology.