Babies born before 39 weeks and via either a caesarean section or induction of labour are at greater risk of developing learning difficulties, new Australian research suggests.
A study led by researchers at the University of Sydney and published in international journal Pediatrics has found an association between planned birth and poor child development at school age.
For every week a baby was born through planned birth before the optimal date this risk increased, according to senior author, Associate Professor Natasha Nassar.
Planned, or scheduled, births occur where a considered decision is made by the doctor and/or parents to deliver a baby before the ideal time of birth at 39-40 weeks' gestation.
Most are conducted to ensure the safety of the mother and baby, however the study has called into question the practice of a planned birth when not unavoidable.
Researchers assessed the development of more than 150,000 children using the Australian Early Development Census instrument in five domains; physical health and wellbeing, language and cognition, social competence, emotional maturity and general knowledge and communication.
Those who scored in the bottom 10 per cent on two or more domains were classified as 'developmentally high risk'.
Compared to children born vaginally following spontaneous labour, the risk of the child being 'developmentally high risk' was 26 per cent higher for those born at 37 weeks gestation.
This risk reduced to 13 per cent for babies born at 38 weeks and this was after taking account of other factors including lower maternal age, maternal smoking and socio-economic disadvantage.
The association between being born early and poorer developmental outcomes is well established and this is further exacerbated in the case of planned birth, says Associate Prof Nassar.
"It's that combined risk of being delivered by these intervention measures and before the due date," she said.
She says delaying the birth by one or two weeks when there is no other risk to the baby or mother could make a huge difference to the child at school age.
"There are women in our analysis where they have no other risk factors that are being delivered early and we don't know why that is," said Associate Prof Nassar.
Jason Bentley from the Menzies Centre for Health Policy, who led the study, believes there is an urgent need for strategies to inform more judicious clinical decision making about the timing of planned birth.
"In cases where labour occurs naturally before 39 weeks or planned birth is unavoidable, it is important that there are appropriate interventions and support in early childhood for these potentially vulnerable children," Mr Bentley said.
Preventing premature births
The findings of the University of Sydney study came at the same time as researchers from the University of Adelaide released information about a drug being trialled to prevent premature birth results.
The encouraging results have been published in the journal Scientific Reports.
Lead author and director of the Robinson Research Institute, Professor Sarah Robertson, says they are now a step closer to understanding the inflammatory mechanisms that lead to premature births and how they can be suppressed.
"By the time the conditions for pre-term birth have already arisen, it's often too late for current treatments to do anything about it," she said. "What we really need is to stop the train at the station, as it were, before it can head down that track. Once it's left the station it's usually too late to stop it."
Pre-term birth, that is a baby born at less than 37 weeks gestation, is the major cause of death in children under five years of age, accounting for 1.1 million deaths across the globe annually.
The main cause of pre-term birth is bacterial infection, in around 50 per cent of cases, and physical injury or stress that causes damage to the placenta.
Twins or triplets are also commonly born pre-term.
Each of these is associated with what researchers describe as an "inflammatory cascade", which activates the mother's immune response and ultimately leads to spontaneous pre-term birth.
This inflammatory cascade is caused by an immune receptor known as Toll-Like receptor 4 (TLR4) that produces effects harmful to pregnancy.
"TLR4 is a trigger of spontaneous pre-term birth," said Prof Robertson. "For this reason, we wanted to test a drug known for its ability to block the actions of TLR4, to see if that would also prevent pre-term birth."
It was (+)-naloxone that protected the mice treated with the drug against bacterial induced pre-term birth. It also protected the mice against stillbirth and offspring death shortly after birth.
"The babies born to mothers treated with (+)-naloxone developed normally and were mostly indistinguishable from those born to the control group," said Prof Robertson.
More research is now under way to determine if the drug or similar drugs could be used in human clinical trials.
If so, they would likely be used in combination with antibiotics, said Prof Robertson.