Children born moderately early at increased risk of developmental delays

Children born moderately early are at an increased risk of developmental disorders, Universities of York, Leeds and Leicester researchers have found.

Developmental disorders such as language delay, cognitive impairment, ADHD and Cerebral palsy were more likely in children born between 32 and 38 weeks’ gestation compared with children born at full term, according to the major new study.

While many of the increased risks are small they could have significant consequences at population level, the authors of the National Institute of Health and Care Research (NIHR) funded study say. 

To reach their findings the researchers examined data from more than 75 studies from around the world, which involved a total of over eight million children. 

Compared with children born at full term, the study identified an increased risk of most developmental disorders. Whilst risks decreased with each week of gestation, there was still evidence of a small increase in risk of several developmental disorders such as cerebral palsy, developmental delay, and cognitive impairment, even when children were born “early term”, between 37-38 weeks.

One of the most common disorders was language delay which affected 222 per 1000 children born between 32-36 weeks, compared with 47 per 1000 for full term children. Many children face low educational attainment during the primary school years, affecting 300 per 1000 children born moderately preterm, compared to 160 per 1000 children born at full term.

While the risk of cerebral palsy is relatively low for all children, the results of the study suggest it is 14 times higher for infants born at 32 to 33 weeks compared with children born at full term. 

The review also found that difficulties faced by children born at 32 to 38 weeks persist through childhood, with evidence of increased risk and prevalence of cognitive impairment and low educational achievement persisting into the high school years. 

Dr Katherine Pettinger, the lead author of the study said it is important to remember that while the study shows an increase in risk for children born moderately early relative to their peers born at full term, many children will not experience any developmental problems.

“The reasons behind our findings are not yet clear, but babies born just a few weeks early have different brain maturation to full term children, and it is possible that birth between 32 and 38 weeks’ gestation may disrupt evolution of neural connections, potentially contributing to developmental disorder,” she said.

“Many babies that are born moderately preterm are delivered early for very good reasons, for example when the mother has a health condition such as preeclampsia. However, understanding the long-term implications of birth before full term may influence obstetric decision making in some cases. It is also vital that all healthcare professionals, and particularly paediatricians, are well informed of the potential consequences of preterm birth so that they can give evidence based information to families and so opportunities for early intervention are not missed. ” 

The researchers do not recommend that all children born between 32 and 38 weeks’ gestation should also receive multiple routine health appointments as many will not show any signs of developmental disorders and this would place significant strain on NHS services. 

They are, however, calling for more communication between schools, parents and health professionals and better support for teachers. 

“The data tells us the effects of being just a few weeks early are still there at primary school age. It therefore makes sense for teachers to be informed if they have students who are born preterm and early term and receive training on how to support them,” Dr Pettinger added.

Risk of Developmental Disorders in Children Born at 32 to 38 Weeks’ Gestation: A Meta-Analysis is published in the journal Pediatrics.