Late Immunization Puts Low-Birth-Weight Babies at Risk

Contact: Diane Langkamp, (614) 722-4957

Written by Darrell E. Ward, (614) 292-8456[email protected]

LATE IMMUNIZATION PUTS LOW-BIRTH-WEIGHT BABIES AT RISK

COLUMBUS, Ohio - Very-low-birth-weight (VLBW) infants are likely to get routine childhood immunizations months later than normal-birth-weight (NBW) children, new research shows.

The study was the first of its kind to look at the timing of immunizations in VLBW children nationally. It found that a delay existed at 12 months of age and was still present even at 36 months of age.

The lack of immunizations places children at particular risk for pertussis, or whooping cough. Children under 12 months of age who develop whooping cough often require hospitalization in an intensive-care unit and occasionally die of that illness.

Many primary-care physicians, and sometimes families, postpone the immunizations fearing that the vaccines are too dangerous for VLBW babies because the infants often have complex medical problems, said Diane Langkamp, assistant professor of pediatrics at Ohio State University, who led the study.

"But the risks of pertussis are actually much greater than the risks posed by the immunizations," Langkamp said.

"Low-birth-weight babies and very-low-birth-weight babies should be immunized on the same schedule as normal-birth-weight babies. There is no reason to delay their immunizations even if they're on oxygen or an apnea monitor."

VLBW babies were those less than three-and-a-half pounds at birth; LBW babies were those between three-and-a-half and five-and-a-half pounds; and NBW were those greater than five-and-a-half pounds.

Langkamp, who has a joint appointment at Children's Hospital in Columbus, published her findings in a recent issue of Archives of Pediatrics and Adolescent Medicine.

The study analyzed data from the 1988 National Maternal and Infant Health Survey and the 1991 Longitudinal Follow-up Survey. It involved 8,285 children whose mothers completed both surveys.

The researchers looked at the age children received their first doses of diphtheria, tetanus, pertussis, and polio vaccines.

The analysis found that VLBW babies had received their first diphtheria, tetanus, and pertussis vaccinations nearly two months later than NBW babies (6.9 months of age vs. 5.2 months of age), while LBW babies received them nearly one month later, at 6 months of age, compared to NBW babies.

The difference continued for later immunizations. NBW babies received their second shot in the series of immunizations at 7.2 months of age, while VLBW and LBW babies received them at 9.4 and 8.0 months of age respectively.

DPT and polio vaccines carry few side effects, said Langkamp, though an older pertussis vaccine had some risk.

"There are isolated cases where, for example, a child may stop breathing momentarily, and it seems to occur after they've had a vaccination. But that occurs more often with the old pertussis vaccine. We've had a newer pertussis vaccine for the past five years that has fewer side effects."

The researchers also found that mothers with less than a high-school education and children who lacked health insurance were least likely to be up-to-date for DPT vaccinations.

Langkamp said that pertussis is most severe in infancy, and occasionally causes death even in normal-birth-weight children under 12 months old.

The risk of death from whooping cough is not high. For every 1,000 children less than 12 months of age who get whooping cough, one is likely to die, she said.

"However, the hospitalization rate among the low-birth-weight babies less than 24 months of age with whooping cough is about 70 percent, which is higher than for normal-birth-weight babies.

"If we can get these kids immunized on time, they'll be more likely to be protected against whooping cough during the period when the disease is more likely to be severe."

Children who get whooping cough at older ages generally don't die from it or end up in the intensive care unit, she said.

Funding for the study was provided a grant from Children's Research Institute in Columbus.

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