Life expectancy three years longer for children born into smaller families in developing world

The findings, being presented at the International Conference on Family Planning in Nusa Dua, Indonesia, show that while family planning programs have sometimes been pitched as ways to moderate population growth and minimize pressure on resource-strapped nations, they have real health impacts on individuals.

"For 40 years, the slogan 'a small family is a happy family' has been used to promote contraceptive use in developing countries," says study leader Saifuddin Ahmed, MBBS, PhD, an associate professor with the Bloomberg School's Department of Population, Family and Reproductive Health and Bill & Melinda Gates Institute for Family and Reproductive Health. "Our new research shows that being born into a small family has health benefits that last throughout the course of your entire life."

Past studies have shown that contraceptive use reduces pregnancy and child mortality, averts maternal deaths and improves the general health of women and children, but little attention has been paid to the actual effect on families of having fewer children. Ahmed and Jose "Oying" Rimon, director of the Gates Institute, found that in families considered small (four or fewer children), the children have a life expectancy that is three years longer than the children in larger families (five or more children) even controlling for infant mortality.

"This finding is profound because life expectancy is like the motherhood of all indicators because it encompasses health, economic and social well-being," Rimon says.

The findings are based on the results of the most recent national Demographic and Health Surveys from 35 developing countries.

Small family size, primarily achieved through the use of contraception, reduces the competition of siblings for both the attention and micronutrients provided by the mother, and also allows the family's often-limited financial resources to be spread farther. This appears to provide a positive healthy developmental environment that reduces mortality in the short- and long-term.

"When births are spread out and mothers can provide more time to each child before the next one is born, it results in better cognitive development and health status while growing up," Ahmed says. "Each child competes with the next for the parents' income, food and housing and having fewer children gives everyone a larger slice of the pie."

The smallest things could make a difference, he says. For example, there may be a smaller risk of exposure to life-threatening diarrhea when there are fewer siblings around to catch and spread it.

"For too long, some sectors have thought about family planning strictly in terms of demographic interests at a population level," Ahmed says. "What our research shows is that family planning is for providing a healthy life for women and for ensuring a healthy environment for the entire family."

Ahmed will present "Small families are healthy families: Evidence of long-term effect of small family size on improving survival status across the lifespan" at 10:30 a.m. local time on Jan. 27, 2016.