Late pre-term infants have higher risks for death in the first month or first year of life, and for cerebral palsy, according to a systematic review.
The absolute incidence of neonatal mortality and morbidity in late pre-term infants (i.e., born before the end of 37 weeks) is low, but it's still significantly higher than in full-term infants, say the authors of the review.
"It is important to realize that infants born late pre-term are not the same population as infants born at term," lead author Dr Margreet J. Teune from Academic Medical Center in Amsterdam said. "There has to be a good indication to induce labour before 37 weeks of gestation."
Dr Teune and colleagues reviewed 22 studies involving more than 29 million newborns: 2,368,471 late pre-term and 27,007,204 full-term.
Death rates in the first 28 days were nearly six times higher for late pre-term infants than for term infants (0.38 vs 0.07%), and the risk of death in the first year was almost four times higher (0.83% vs 0.27%), the researchers reported online in the American Journal of Obstetrics and Gynecology.
Late pre-term infants also had higher rates of mechanical ventilation, respiratory distress syndrome, narcotising enterocolitis, intraventricular haemorrhage, and other adverse outcomes.
What causes these deaths?
Over the long term, late pre-term infants were more likely to suffer from cerebral palsy, mental retardation or schizophrenia, or psychological disorders than were term infants.
For healthy late pre-term infants, a slightly increased risk for developmental delay and school-related problems persisted for the first five years of life, and their reading and math skills were worse than those of term infants, according to several studies involving a total of more than 160,000 babies.
Data on more than 600,000 children showed that late pre-term infants were also less likely than full-term babies to finish high school or to complete university.
"I think that long-term differences between individuals born term and late pre-term are clinically important," Dr Teune said. "Infants born late pre-term seem to have a higher risk for long-term problems, so we have to take this information into account when weighing the risks and benefits to mother and child to determine the optimal obstetrical management."
"It is crucial that we do more studies in this area, especially randomised studies comparing early delivery versus delayed delivery," Dr Teune concluded. "The Dutch obstetric consortium, among others, is involved in trials on women with ruptured membranes, growth restriction, and hypertension."
(Reuters Health, Will Boggs MD, August 2011)