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Moderately premature infants born at 30 to 34 weeks gestation tend to suffer substantial health problems

Nearly 4 percent of infants in the United States are born moderately premature (30 to 34 weeks gestation). These infants tend to suffer more significant health problems in the hospital after birth than full-term infants (37 weeks or greater), according to a new study. Researchers found that nearly 46 percent of moderately premature infants received assisted ventilation after birth, and 3 percent still required supplemental oxygen at 36 weeks. Within 3 months of discharge, 11 percent of these infants were readmitted to the hospital. Hospital readmission was more likely among male infants and those with chronic lung disease.

In a study supported by the Agency for Healthcare Research and Quality (HS10131), researchers analyzed health outcomes of 850 moderately premature infants born at 10 hospitals in California and Massachusetts from 2001 to 2003. (Admission to the neonatal intensive care unit is mandatory for all babies born at less than 35 weeks gestation at these 10 hospitals.) They also examined responses to telephone interviews with 677 families of the infants 3 months after hospital discharge.

The study did not include a comparison group of full-term infants. However, the 45.7 out of 1,000 moderately premature infants in this study who received assisted ventilation is more than 4 times the 10.4/1,000 rate other studies have found in term infants. Also, pneumothorax rates have been reported in full-term infants as 0.17 to 0.70/1,000 live births compared with 1.6/1,000 among the premature infants in this study. Meningitis rates were also higher among this group than have been reported in full-term infants. Also of note, a birthweight of 2,000 g (about 4.5 lbs) or more did not protect these moderately premature infants against the need for assisted ventilation or hospital readmission. Thus, babies whose weight might lead many clinicians to consider them to be "big preemies" nonetheless experience considerable health problems, note the researchers. They suggest that treatment guidelines not group all babies less than 37 weeks gestation into a single category.

See "Unstudied infants: Outcomes of moderately premature infants in the NICU," by Gabriel J. Escobar, Marie C. McCormick, John A. Zupancic, and others, in the July 2006 Archives of Disease in Childhood: Fetal and Neonatal Edition 91(4), pp. F238-F244.

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