Babies born a few weeks prematurely are at increased risk of health problems, such as jaundice and low blood sugar, so expectant mothers should not hasten delivery, researchers said on Monday.

“Conventional wisdom has been that babies who were near-term, but still premature, would do as well as full-term babies…But those of us who take care of these children know from experience that they may have more jaundice or hypoglycemia than full-term infants do,” said study author Dr. Marvin Wang of Massachusetts General Hospital for Children.

Researchers at the Boston hospital compared 95 full-term babies born at 37 weeks gestation or later with 90 babies born at 35 or 36 weeks gestation.

Premature babies were significantly more likely to have health problems and 18 had multiple ailments, while none of the full-term babies had more than one problem.

Among the conditions were jaundice, hypoglycemia (low blood sugar), respiratory distress, the need for intravenous feeding and difficulty maintaining body temperature.

Premature babies often require different and more expensive treatment, and the cost of their initial hospital stays averaged $2600 more than full-term infants.

The study, which was published in the journal Pediatrics, noted that some mothers schedule Caesarean deliveries before their due date to avoid muscle tearing or stretch marks or to better suit their schedules or those of their doctors.

“There can be valid medical reasons for delivering early, but our study calls into question the presumption that elective delivery at 35 or 36 weeks poses no risk to the infant,” Wang said.