Birth Spacing: An Overlooked Benefit of Birth Control

Worldwide, more than 4 million children die in the first 4 weeks of life, and 28% of these deaths are thought to be due directly to preterm birth. Reducing child mortality by 2015 is one of 8 goals in the United Nations Millennium Declaration, adopted by more than 180 nations. Birth spacing is mentioned in the strategies set out to achieve the goals but its potential seems underemphasized.

A meta-analysis of 67 studies looking at the association between birth spacing and risk of adverse perinatal outcomes (preterm birth, low birth weight, and small for gestational age) found that:

Interpregnancy intervals shorter than 18 months and longer than 59 months are significantly associated with increased risk of adverse perinatal outcomes. These data suggest that spacing pregnancies appropriately could help prevent such adverse perinatal outcomes.

From the study's author:

"The financial cost of birth spacing programs is lower than the financial cost of infant deaths, of course," Conde-Agudelo said in an e-mail.

Pregnancy and nursing use up nutrients in a woman's body, he said, and for a woman to get pregnant again before she has a chance to recover nutritionally may mean higher risks for the baby.

As for why long intervals between births cause problems too, he speculated that time could diminish a woman's reproductive capacity and that factors that decrease fertility also could lead to poor fetal development.

The analysis found that for each month under 18 months between pregnancies, the risk of premature birth increased 1.9 percent. For each month longer than 59 months between pregnancies, the chances of premature birth climbed 0.6 percent.

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Conde-Agudelo said the risks of short and long birth intervals held true for both developing and developed nations, showing up in U.S. studies and in research from Europe, Africa and Latin America.

This finding of universal risk is very interesting and leads me to believe that something other than maternal nutritional depletion may play a role.