Stanford University Home

Stanford News Archive

Stanford Report, June 11, 2003

Weekends no more deadly for births, says pediatrician The findings help explain a mystery regarding apparent mortality risks


Babies born on the weekends tend to be smaller and sicker than those born during the week, said researchers at Lucile Packard Children’s Hospital and the School of Medicine.

The newfound discrepancy debunks concerns that higher death rates for newborns arriving on the weekend are due to inadequacies in hospital staffing or experience.

"We’ve found that weekends are not an inherently more dangerous time to be born," said senior author and neonatologist Jeffrey Gould, MD. "Instead, the fact that there is a proportionally higher percentage of very tiny babies — who are more likely to die — born on weekends than during the week inflates the observed mortality."

The research, published today in the Journal of the American Medical Association, should allay the fears of women with uncomplicated, full-term pregnancies who begin labor on the weekend.

Weekend deliveries have been saddled with an undeserved, seemingly deadly reputation after studies published in the 1970s and ‘80s. "It stems from research that suggested that infants born on weekends are more likely to die than those born during the week," said Gould, professor of pediatrics. "One thing these studies didn’t do, however, was control for the fact that there might have been more emergency births on the weekend."

When Gould and his colleagues pooled data from more than 1.5 million births throughout California from 1995 to 1997, they confirmed that overall neonatal mortality increased on Saturdays and Sundays. They also found that there are proportionally fewer births in general on the weekend than during the week. When they homed in on the birth weights of this subset of newborns, they discovered why.

Many physicians prefer to induce labor in women whose fetuses are at risk, but healthy enough for delivery, during the week when ample support staff is available. The same is true of Caesarean sections, which were used to deliver about 20 percent of the infants in the study.

This tendency to favor weekdays is reflected in the fact that there were 17.5 percent fewer births on the weekend than would have been expected had the births been distributed randomly.

But while inducing labor or performing a Caesarean is a reliable way to get a baby out, it is much harder to thwart premature labor to keep an underdeveloped baby in the uterus. The battle to prevent delivery of these sickest fetuses can as easily be lost on the weekend as during the week. The researchers found that 0.95 percent of infants born during the week could be classified as "very low birth weight." In contrast, infants of very low birth weight made up 1.11 percent of all weekend births.

When the researchers correlated mortality rates with birth weight, the difference between weekday and weekend birth vanished, confirming their theory: Fewer deliveries of more acutely ill newborns create the perception that all weekend births are more dangerous.

Gould and his colleagues are now stratifying the data for individual hospitals in California. Although the findings cannot be generalized beyond California, data exist that will allow similar comparisons on a nationwide level, said Gould.

This analysis was performed in collaboration with researchers at UC-Berkeley and the State Department of Health Services. It is one of the first of Packard Children’s Hospital’s new Perinatal Outcomes Research Project, which strives to correlate neonatal outcomes with quality of care in more than 60 neonatal intensive care units throughout the state.

Faculty changes announced (5/7/03)

Lucile Packard Children’s Hospital