Study: Developmental Delay for Late Preterm Babies

Developmental Risks Are Possible for Babies Delivered at 34 to 36 Weeks of Pregnancy

Reviewed by Laura J. Martin, MD on May 31, 2011
From the WebMD Archives

May 31, 2011 -- Late preterm babies born from 34 to 36 weeks of pregnancy may be at an increased risk for modest developmental and academic problems up to age 7, when compared to babies born at full term, according to a new study.

Most research on the risks associated with preterm birth looks at infants born between 23 and 28 weeks of pregnancy, but significant brain development takes place in the last four to six weeks of gestation. Interrupting these processes, coupled with the often complicated medical problems faced by premature babies, may account for an increased risk of developmental and academic problems.

"Although late preterm infants were previously considered similar to term infants, emerging evidence suggests that significant adverse developmental outcomes among late preterm infants, which further indicates that longer-term outcomes of prematurity, remain a concern even for those infants born at the more optimistic late-preterm stages of pregnancy," conclude study researchers led by Jennifer E. McGowan, of the School of Nursing and Midwifery at Queen's University Belfast in Belfast, U.K.

The study suggests that the closer to term a pregnancy goes, the lower these risks. Late preterm babies fare better than those born earlier, but both groups are at greater risk for developmental problems than term infants.

Researchers analyzed 10 studies looking at early childhood outcomes among babies born at 34 to 36 weeks. Babies born between 34 and 36 weeks gestation were at greater risk for developmental delays, and scored lower on standardized tests of academic achievement, compared to infants born at term. Late preterm infants were also more likely to require early intervention to help them catch up, and were more likely to be underweight and shorter than infants born at term, the study shows.

'Consequences to Early Delivery'

"In the past, only very, very tiny preterm babies were believed to be at risk for problems later in life," says Shoo Lee, MD, the chief of pediatrics at Mount Sinai Hospital in Toronto. "And we are realizing that this is not true and that all preterm babies including those born between weeks 34 to 36 are at risk."

This is particularly worrisome because increasing numbers of babies are being born prematurely, he says. This is due to fertility treatments, advanced maternal age, and other social issues including scheduled delivery.

"There are consequences to delivering early," he says.

"These babies are vulnerable and moms should be on the lookout for signs of delay," he says.

Early signs may include inattentiveness, excessive crying, and difficulty forming relationships. "There is a range of normal and if the mother finds that a baby not doing well, it doesn't mean that it is abnormal, just that it may need to be evaluated," he says.

Mark Batshaw, MD, chief academic officer at Children's National Medical Center in Washington, D.C., says that it is a spectrum. "The more premature you are, the more at risk you will be for problems."

"Some thought that if you made it to 34 weeks, things will be OK, but this study says 'we don't know," he says. "Babies were meant to stay inside for 40 weeks, and if it is less than that, they are at greater risk for problems."

"If the child is lagging in development, they should be referred for early intervention as soon as possible," he says. "Every well-baby checkup should involve a developmental screening to see if the child is starting to lag and if that lag is seen on two successive evaluations, a referral for formal testing and evaluation may be warranted."

Show Sources


McGowan, J.E. Pediatrics, 2011.

Shoo Lee, MD, chief, pediatrics, Mount Sinai Hospital, Toronto.

Mark Batshaw, MD, chief academic officer, Children's National Medical Center, Washington, D.C.

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