12/04/2013 05:00 EST | Updated 02/03/2014 05:59 EST

Obesity prevention can start during pregnancy, infancy

It's never too early to take steps to prevent child obesity, say doctors who are calling pregnancy and infancy key times to act.

Wednesday's New England Journal of Medicine includes a commentary by the two U.S. doctors titled "How Early Should Obesity Prevention Start?"

Dr. Matthew Gillman and Dr. David Ludwig of the nutrition department at the Harvard School of Public Health in Boston say that during pregnancy excessive weight gain and risk factors such as gestational diabetes can change growth and metabolism in the fetus. If a female child grows up obese and becomes pregnant, then the cycle continues.

Fortunately, research on the prenatal period and first year of life point to clues to reducing obesity in women and preventing it in children.

The researchers pointed to excessive gestational weight gain, maternal smoking during pregnancy, fewer months of breastfeeding and shorter duration of sleep during infancy as potential targets. But whether reducing gestational weight gain pays off in reduced child obesity risk still needs to be proven.

The prenatal and postnatal periods are also ripe times to change behaviour since:

- Women appear keen to change their behaviour then to benefit their children.

- There's potential to improve health-care delivery during pregnancy and infancy when routine medical care is frequent.

- The periods are relatively brief and interventions to change behaviours often work best in the short term.

- Making changes during pregnancy and keeping them up after birth reduces the risk of maternal obesity in future pregnancies.