Study Sees Need to Pace Pregnancies

Women who again become pregnant sooner than 18 months after giving birth face a higher risk of having a small, premature or low birth-weight baby, according to a study.

The report, published in today’s Journal of the American Medical Assn., also found that spacing pregnancies more than five years apart brought a higher risk of complications.

The study provided the most comprehensive look at the issue of spacing between pregnancies, which over the years has produced myriad recommendations.

“Before we could talk about the importance of good spacing, but we couldn’t talk about what it means,” said Dr. Nancy Green, medical director of the March of Dimes. “Now the advice we give to a woman is very clear.”

Dr. Agustin Conde-Agudelo of the Santa Fe de Bogota Foundation in Colombia, who led the study, said the findings could prevent thousands of infant deaths each year.

Premature infants have a greater risk of dying or suffering developmental deficits. Low-birth-weight babies -- those under 5.5 pounds -- and babies born small for their gestational age also face greater risks.

“The new evidence presented in our study makes child spacing compelling as a health issue of global importance,” he said.

The research analyzed data from 67 studies conducted in the U.S., Europe and underdeveloped nations during the last 30 years.

Conde-Agudelo said the data were adjusted for socioeconomic conditions and other factors, therefore “the findings can be applied to both developed and developing countries.”

A separate analysis of U.S.-based studies produced similar results, he said.

The report found that women who became pregnant sooner than 18 months after giving birth increased their risk of having a premature infant by about 2% for every month short of 18 months. The risk of having a low birth-weight infant was increased by 3% each month. The risk of having infants small for their gestational age was 0.5% higher for every month.

Conde-Agudelo said a possible explanation for the problems is that pregnancies in close succession probably deplete the mother’s nutritional stores. Published studies have demonstrated that a mother’s level of folate drops and remains low long after she gives birth, he said. Insufficient folate is associated with spinal defects, premature birth and low birth weight.

For woman who became pregnant after five years, the risk of complications increased by less than 1% a month.

Conde-Agudelo said it was less clear why long periods between pregnancies were associated with more complications. Researchers said it was possible that mothers in this group were older or had more health problems that might have affected their pregnancies.

The highest risks found by the study were for pregnancies separated by fewer than six months, which were associated with a significantly higher risk of complications and a higher rate of infant mortality and stillborn births.

Rachel A. Royce of Research Triangle Institute International, who wrote an editorial accompanying the study, noted that 6% to 10% of infants worldwide were conceived sooner than six months after their mother had given birth to an older sibling.

She said additional studies could explore whether giving folate supplements to women after delivery would improve the health of later children.

Royce called for “the translation of these solid research findings into practice.... This study is important because a whole lot of births occur with short spacing.”

But Dr. Mark A. Klebanoff, director of the National Institute of Child Health and Human Development, said he believed the study overstated the risks.

Klebanoff, who studied birth spacing in the 1980s, said the effects of spacing were influenced by many factors.

The study’s data, he said, were not detailed enough to adjust for all the possible conditions. He noted, for example, that the study did not separate women who had a history of problem pregnancies. Those women would be high-risk under any spacing, he said, and would skew the figures.

The report’s “gloom and doom prediction is more gloomy and doomy than it might have been,” Klebanoff said, adding that he did not think there was an “optimal” time that could be applied to all.

The study was funded by the U.S. Agency for International Development, which planned to use the results in family planning programs it funded in underdeveloped countries.

The report came one month after the White House recommended cuts in the amount the agency would spend on family planning initiatives, a move that generated opposition from Democrats.

Dr. James Shelton, a senior scientist at the agency, said the study showed that family planning was still a priority.