New York, April 17 (IANS): Women who breastfeed their infants for at least 90 days smoke less in the months following childbirth than women who breastfeed for a shorter duration or who do not breastfeed at all, says a new study.

While a large number of women quit or reduce smoking upon pregnancy recognition, many resume smoking postpartum.

"Although women decreased their tobacco consumption across their pregnancy, by nine months postpartum they had substantially increased their smoking," said study author Shannon Shisler.

"Increase in tobacco consumption after the birth of a child may have harmful effects on both the mother and the infant, who is at higher risk of exposure to environmental tobacco smoke," Shisler added.

Previous research has estimated that approximately 70 percent of women, who quit smoking during pregnancy, relapse within the first year after childbirth.

And of those who relapse, 67 percent resume smoking by three months and up to 90 percent by six months.

The new study indicated that the only significant predictor of change in smoking behaviour for women, who smoked during pregnancy, were among those who breastfed their infants.

It followed 168 women who were smokers during pregnancy from their first prenatal appointments through nine months after childbirth.

The researchers looked at breastfeeding, use of other substances, and if their partners were smokers, in order to help determine possible predictors of changes in smoking habits.

"Breastfeeding seems to be a protective factor against increase in smoking after childbirth, so interventions should educate women about breastfeeding to maximize effectiveness.

"Supporting women through at least three months of breastfeeding may have long-term benefits in terms of smoking reduction," the researchers noted.

The findings were published in Oxford University Press journal Nicotine & Tobacco Research.