June 22, 2000 -- Premature babies who are very small at birth run an increased risk of developmental problems that can be detected as early as 18 months of age, according to a study in the journal Pediatrics. Experts believe these problems will become more common as medical advances allow the survival of infants born more than three months premature and weighing 1 pound, or even less, at birth.
Study author Betty Vohr, MD, and her colleagues studied the conditions at 18-22 months of more than 1,100 extremely low birth-weight children (defined as babies weighing about 1 to 2 pounds at birth) delivered at 12 hospitals around the U.S. in 1993 and 1994. They evaluated the babies' development, mental functions, and medical and social histories. According to Vohr, the tiniest baby weighed only 14 ounces at birth.
In an interview with WebMD, Vohr stresses that the children's scores in these areas were evaluated on an age-adjusted basis. For example, she says, "a child born at 28 weeks might have a chronological age of 6 months, but a developmental age of only 3 months." This is important because, in such a child, certain developmental milestones can continue to occur after birth -- just as if the baby had remained in the womb those remaining three months.
Overall, development was normal in over half of these children by age 18 to 22 months. Seventeen percent of the children had cerebral palsy, 11% had some form of hearing impairment, and 9% had vision problems. The lower a child's birth weight was, the greater the risk of visual impairment or neurological problems.
Children who had steroid therapy for chronic lung disease immediately after birth seemed to have the most severe problems, perhaps because they were the sickest infants. It's not known how steroids may have produced this effect, but the researchers point out that steroids may have a toxic effect on the brain. Vohr tells WebMD that the use of neonatal steroids is now being re-evaluated.
The researchers also point out that having a higher socioeconomic status may blunt some of the worst effects of being born so early. Factors such as the mothers' education level and race were strongly associated with their children's scores on tests of mental development at 18-22 months of age.
These findings suggest that "higher maternal education is protective," Vohr says, and that "families with more socioeconomic problems are at higher risk of having a premature child with developmental problems." Vohr is director of neonatal follow-up at Women's and Infants Hospital and professor of pediatrics at Brown University, in Providence, R.I.
"This study is a useful addition to the literature," says Stephen Bates, MD, who reviewed the report for WebMD. The fact that so many premature children are surviving "is a reflection of excellent perinatal care and incredibly expensive neonatal care. ... But it raises ethical issues. ? These children are going to have a huge number of problems."
Bates, a pediatric neurologist at Arkansas Children's Hospital in Little Rock, also warns that the children examined in this study may encounter even more problems once they enter school.
"That is absolutely correct," Vohr says. "If you look at studies of school performance of children who weighed less than [2 pounds] at birth, half of them require special help. However, with the proper intervention, many of those problems can be addressed."
Vohr prefers to take a brighter outlook on these findings. "Overall, 49% of the children had poor outcomes at 18 months of age, but that means 50% of them had good outcomes," she says. "Eighty-three percent of them were walking, and 80% of them were able to feed themselves independently. I'm optimistic that these children will be doing even better by age 4 to 5 years."
Bates and Vohr urge women to everything they can to ensure a healthy pregnancy and decrease the risk of delivering prematurely. "For every week you can gain of intrauterine life and every [few ounces of birth weight] you can gain, it seems to make a significant difference in outcome," Bates says.
Vohr adds: "Seek prenatal care early. Get good nutrition, don't smoke or drink, engage in moderate exercise -- maintain a healthy lifestyle."
If you already have a baby who was premature, she advises, "ask about early interventions. Talk to the neonatologist and other experts available. Most of all, just provide a lot of love and nurturing for your baby."
- Premature babies who have extremely low birth weights run the risk of developmental problems, including cerebral palsy, hearing impairment, or vision problems.
- As medical technology improves, more premature babies are surviving, so these problems may be greater in the future.
- Half of the extremely low birth weight babies, though, have normal development, and researchers suspect that others may catch up, developmentally, by age 4 or 5.