Factors Other than Age Affect Preemie Survival

"¢ Five factors influence survivability"¢ Studied babies weighing less than 2.2 pounds"¢ Developed Web tool to aid treatment decisions

Newswise — Premature infants are more likely to survive—and survive without a disability—if the baby is female, from a single birth, is of a higher birth weight, and if the mother has received steroids to help the baby's lungs mature before birth, says research partially conducted at UAB and published in the April 17 issue of the New England Journal of Medicine. The combination of factors is more important than the single issue of gestational age.

Waldemar Carlo, M.D., professor and director of the UAB Division of Neonatology, said researchers in the National Institute of Child Health and Human Development (NICHD) Neonatal Research Network observed 4,446 infants born between 22 and 25 weeks gestational age. These extremely low birth-weight infants, those weighing less than 1,000 grams, or 2.2 pounds, make up about 1 percent of babies born in the United States each year, or roughly 40,000 babies a year. More than 150 extremely low birth-weight babies are born at UAB each year.

Carlo, who also holds the Edwin M. Dixon Chair in Neonatology, said this population of babies was studied by UAB and other researchers in the NICHD Neonatal Research Network because each day physicians and new parents have to make difficult decisions on the types of care to provide to extremely low birth-weight infants, the smallest, most frail category of preterm infants. "These infants are born in the 22nd through the 25th week of pregnancy—far earlier than the 40 weeks of a full term pregnancy," Carlo said. "Many die soon after birth, despite our best attempts to save them. Some survive and reach adulthood, relatively unaffected. The rest experience some degree of life-long disability, ranging from minor hearing loss to blindness, to cerebral palsy, to profound intellectual disability. In deciding the kind of care to provide, traditionally physicians have relied heavily on an infant's gestational age because it is known to play a large role in the infant's survival. We knew that the closer a baby was to the 25th week, the better its chances. But, it often is hard to calculate a baby's gestational age. It's easy to miscount by a week, and that could make a large difference in the baby's chances of survival. We wanted to know other factors that play roles in survivability so that we can help new parents make decisions regarding the care of their premature infant."

Using standardized measures of mental development, vision and hearing, the researchers assessed the health status of surviving infants when the infants were from 18 to 22 months corrected age—the age they would have been had they been born full term. Carlo said 21 percent lived and did not have a disability while the remainder died or experienced some degree of disability. They determined that infants were more likely to survive—and more likely to survive without disability—if they were of older gestational age, their mothers had been given corticosteroids to help mature their lungs, if they were female, were a singleton rather than part of a multiple birth, and been of a higher birthweight. Carlo said it is important to note that UAB's survivability rates for all premature babies, and survivability with no apparent disability, is significantly better than the national average.

"Our study found that that it is much more accurate if the infant's assessment is based on the combination of these five factors, rather than just on gestational age, Carlo said.

Carlo said the study involved only infants born at level III neonatal intensive care facilities and the study findings may not apply to infants born at level I and level II facilities. Level III facilities like UAB are the most advanced of neonatal care facilities. They offer the highly specialized medical care that extremely low birth weight infants need to survive. UAB is the only full service level III facility, with neonatologists on staff 24 hours a day, seven days a week in the state.

Carlo said this study provides what may be the largest source of information on the survival of extremely low birth-weight infants. As such, the NICHD is making it available to parents and physicians on the NICHD Web site [http://www.nichd.nih.gov/about/org/cdbpm/pp/prog_epbo/]. Doctors and parents can type certain key characteristics about a particular infant into a Web form. A program will provide statistics about survival and disability, based on the experiences of the 4000 infants in the network.

"The Web form can be a useful reference for outcome data for a certain set of circumstances," Carlo said. "We know parents and physicians need more information when deciding the course of treatment for an extremely low birth-weight infant. It will generate statistics, based on the factors in the NICHD article. The Web tool is only intended to inform treatment decisions, not predict what will happen. Every baby is an individual human being and deciding what kind of care to provide is best done by the family and the health care team."

The NICHD, an institute of the National Institutes of Health (NIH), sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's Web site at http://www.nichd.nih.gov/. UAB is one of the original eight NICHD research sites commissioned in 1986 and is the only facility in the country that is involved in all three of the NIH research initiatives for maternal, child and family health, the Neonatal Research Network, Maternal-Fetal Medicine Units Network and the Global Network for Women and Children Research.The under-construction UAB Women and Infants Center, scheduled to open in 2010, will house a new Regional Neonatal Intensive Care Unit/Continuing Care Nursery (RNICU/CCN). With this facility, UAB will be one of the largest RNICU/CCN units in the country and one of the first hospitals in the Southeast to offer single room neonatal intensive care.