Factors That Influence Premature Infant Survival, Disability
Based on observations of more than 4,000 infants, researchers in an NIH newborn research network have identified several factors that influence an extremely low birth weight infant's chances for survival and disability. The findings offer new information to physicians and families considering the most appropriate treatment options for this category of infants.
Every day, physicians and new parents must struggle with the type 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. Many die soon after birth, despite the best attempts to save them, including the most sophisticated newborn intensive care available. Some survive and reach adulthood, relatively unaffected. The rest will experience some degree of life long disability, ranging from minor hearing loss to blindness, to cerebral palsy, to profound intellectual disability.
The study authors referred to the issue of providing intensive care for extremely low birth weight infants. For example, physicians and family members may be reluctant to expose an infant to painful life support procedures if the infant is unlikely to survive. In such cases, they may opt for "comfort care," which provides for an infant's basic needs, but foregoes painful medical procedures. In deciding the kind of care to provide, specialists at intensive care facilities traditionally have relied heavily on an infant's gestational age -- the week of pregnancy a premature infant is born. Gestational age is known to play a large role in the infant's survival. For this reason, in many facilities, intensive care is likely to be routinely given to infants born in the 25th week of pregnancy, whereas infants born in the 22nd week may be more likely to receive comfort care.
The study authors noted, however, that it is often difficult to assess gestational age. Moreover, an estimate that is inaccurate by only a week could result in an infant receiving care that was not appropriate for his or her individual case. To identify other factors that influenced survival and disability risk, the study authors observed more than 4,000 extremely low birth weight infants in their network.
The researchers published their findings in the April 17 New England Journal of Medicine. In addition to gestational age, factors influencing survival and risk of disability consisted of: whether the baby is male or female (sex); birthweight; whether the baby was a single baby, or one of two or more infants born; and whether the baby's mother was given medication during pregnancy to prompt the development of the baby's lungs. Known as antenatal steroids, these drugs are typically given to women in premature labor, or who are at known risk for giving birth prematurely.
Physicians and parents may access an online tool that generates statistics, based on the factors the researchers listed in their article, at www.nichd.nih.gov . By specifying the baby's sex, weight, and information related to each of the variables listed above, physicians and family members can generate composite statistics on infant outcomes, based on the experiences of extremely low birthweight infants in the NICHD Neonatal Research Network study. The Web tool is not a substitute for a physician's careful assessment, but physicians and families may find the statistics it generates useful when considering the most appropriate care to provide an infant.
"Every individual is different, and no single tool can precisely predict a given baby's chances of survival or disability," said Duane Alexander, M.D., director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the NIH Institute that supports the Neonatal Research Network. "However, the researchers' findings, and the tool they developed, provide important information that physicians and family members can consult to help them make the most informed treatment decisions possible."