Preterm birth, even by 2 or 3 weeks, tied to health risks in early years

A recent study suggests that health outcomes of moderate or late preterm (32-36 weeks) and early term (37-38 weeks) infants are worse than those of full-term (39-41 weeks) infants in the early years of life and that babies born even a few weeks early have worse health outcomes.

Researchers analyzed data from the Millennium Cohort Study on more than 18,800 UK infants born between 2000 and 2002 for the effects of gestational age at birth on health outcomes at 3 and 5 years. They assessed outcome measures of growth, hospital admissions, longstanding illness or disability, wheezing or asthma, use of prescribed drugs, and parental rating of their children’s health.

The analysis showed a gradient of increasing risk of poorer outcomes with decreasing gestation, suggesting a “dose-response” effect of prematurity. The greatest contribution to disease burden at 3 and 5 years was seen in babies born moderate or late preterm or early term. Population attributable fractions for having at least 3 hospital admissions between 9 months and 5 years were 5.7% for birth at 32 to 36 weeks and 7.2% for birth at 37 to 38 weeks compared with 3.8% for infants born very preterm (<32 weeks). Similarly, population attributable fractions of 2.7%, 5.4%, and 5.4% for limiting longstanding illness at 5 years were found for very preterm birth, moderate or late preterm birth, and early term birth, respectively.

Both moderate or late preterm and early term babies required readmission to a hospital in the first few months more often than full-term babies. Those born between 33 and 36 weeks had an increased risk of asthma and wheezing.

The researchers concluded that it is inappropriate simply to group babies as preterm or term, because their study demonstrates an increasing risk of adverse outcome with increasing prematurity, even approaching full-term gestation.

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