July 7 2008
The Tiniest of Grasps — Study Helps Predict Outcomes in Extremely Premature Infants
By Kim M. Norton
For The Record
Vol. 20 No. 14 P. 24
New research indicates there are five factors, not just one, that need to be considered. Plus, a Web-based tool has been developed to help practitioners quickly assess the likelihood of death or disability.
When dealing with the tiniest of human beings, information is key—and the amount of available information can be critical. Until now, gestational age has been the foundation for making decisions regarding extremely premature infants. But new research indicates that four additional factors can provide more information and invaluable statistics concerning extremely premature infant survival rates and long-term disability risks.
A recent study published in The New England Journal of Medicine (“Intensive Care for Extreme Prematurity — Moving Beyond Gestational Age”) identified four additional factors that should be considered when making decisions regarding care for an extremely premature infant. An infant born before the 37th week of gestation is considered premature, while an extremely premature infant is born between the 22nd and 25th weeks of gestation.
“In the United States, approximately 12% of babies are born premature, with 75% of them being born between 34 and 37 weeks,” says Rosemary D. Higgins, MD, a neonatologist and program scientist for the National Institute of Child Health and Human Development Neonatal Research Network. “A very small amount of infants—less than 1%, or 40,000 babies per year in the U.S.—are born between the 22nd and 25th week of pregnancy. This is clearly a population in need of intensive care.”
According to the researchers, the five factors to be considered when dealing with premature infants are gestational age, sex, whether the infant was exposed to antenatal corticosteroids, whether the child is a single or multiple birth, and birth weight. “None of these criteria is necessarily groundbreaking [in neonatology] but, used together, these factors provide more information in regard to the infant’s survival and disability risk,” says Higgins, one of the study’s authors.
When faced with an infant weighing 1,000 grams (2.2 pounds) or less, the decisions aren’t easy or straightforward. Currently, every attempt is made to assist these extremely fragile infants, including undertaking painful, lifesaving procedures that may be in vain if the infant is not strong enough to withstand the measures. Many die shortly after birth, and those who do survive can have lifelong disabilities, ranging from minor hearing loss and blindness to cerebral palsy and profound intellectual disability.
Collecting the Data
Researchers at the National Institute of Child Health and Human Development Neonatal Research Network, a part of the National Institutes of Health, studied more than 4,400 infants born between the 22nd and 25th weeks gestation from January 1998 to December 2003. The infant population came from 19 centers of the Neonatal Research Network, and all were born in level 3 nurseries (departments equipped to handle complicated births). If infants were moved from the birth hospital, they were not included in the study, according to Higgins.
In compiling and studying the data, researchers created a Web-based tool populated with the study’s outcomes to provide another resource for families and physicians looking for statistics on the risk of death and disability (available at www.nichd.nih.gov/about/org/cdbpm/pp/prog_epbo). It generates a statistical outcome based on criteria that is entered and then matched against the database of study cohorts.
“I have used this Web-based tool in my practice and find that it brings other significant information into the equation,” says Henrietta S. Bada, MD, a neonatologist at the Kentucky Children’s Hospital at the University of Kentucky in Lexington. “It gives us and the families statistical outcomes based on the infant’s situation that provide more information.”
With the additional criteria and the Web-based tool to consult, physicians have more access to information and can provide an evidence-based outcome derived from an infant born with similar circumstances. “This study is significant because we are giving families and their physicians more information to base their decisions on. It is by no means intended to replace a physician’s advice but is designed to offer more information based on the five factors together. Each child is unique and has unique circumstances,” says Higgins.
1. Age: “Traditionally, the obstetrician dates the pregnancy based on the mother’s last menstrual period or early ultrasound. But, occasionally, the mother cannot remember the exact date of her [last period] and the dating may be off. It is then that we must rely on the attending pediatrician to assess the gestational age of the infant,” says Higgins. It is often difficult to accurately estimate gestational age, and a preterm infant may be as much as one or two weeks younger or older than believed, she adds.
Complicating gestational age can be birth weight. Should an infant weigh more or less at birth, it can be assumed that the gestational age is inaccurate, in which case a pediatrician is consulted to determine the infant’s exact age. As medicine and medical technology evolve, the threshold for survival is lowered. “In the past, 25 weeks gestation and 600 grams were the limit. This study lowers the gestational age to 22 weeks and 401 grams, and we are seeing infants survive,” says Bada.
2. Sex: “Girls have a biologic difference from boys that gives them a one-week advantage, which enhances their survival rate even if both are the same gestational age,” says Higgins. The reason behind this biologic difference is not yet known and clearly warrants more research, she adds.
3. Antenatal corticosteroids: Exposure to antenatal corticosteroids, which prompt the development of the infant’s lungs, were shown to be a factor in determining care protocol. “If the mother is at risk for preterm labor, steroids can be administered if preterm delivery is anticipated to happen within the week to enhance organ growth to increase the infant’s chance of survival,” says Bada
4. Single or multiple birth: Multiple pregnancies are at an increased risk of preterm labor, making it more likely that the baby will require intensive care. “The mother’s health was not factored into this study, but there is a relationship between fertility treatments and multiple births. However, it is not known how fertility treatments affect the premature infant,” says Higgins.
5. Birth weight: The greater a premature infant’s birth weight, the greater his or her chances of being healthy. Babies weighing less than 600 grams are the most fragile and are less likely to survive compared with those weighing more than 600 grams at birth, says Bada.
Knowing the Odds
Most of the factors associated with preterm birth are already set. “Knowing the gestational age and sex of the infant, whether it is a single or multiple birth, and if the infant was exposed to corticosteroids all influence how the family and the physician want to proceed,” says Higgins.
In the majority of cases, preterm labor is already a concern and knowing each of these factors for each week or day that pregnancy continues influences the course of action. “Any information that is known before the baby is born is critical to making decisions. Having this reference set is a good resource and allows the physician and the parents to make informed decisions,” says Bada.
“Every newborn has its own unique circumstances, and all treatment options should be carefully considered. As useful as this tool can be, it is merely providing outcomes for babies followed in the study and should not be taken as advice for treatment,” adds Higgins.
— Kim M. Norton is a New Jersey-based freelance writer specializing in healthcare related topics for various trade and consumer publications. She can be contacted at email@example.com.