Quitting Smoking for Your Baby — Before Birth

Quitting smoking while pregnant reduced risk of very underweight babies

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Quitting smoking at any time is tough. The extra effort to quit smoking while pregnant, however, can significantly benefit your baby.

A recent study found that babies of women who quit smoking were no more likely to be born underweight than babies of those who had never smoked.

However, babies born to women who smoked during pregnancy were over three times more likely to be in the less than 10th percentile for birth weight.

The study also found that women who quit smoking tended to gain a few extra pounds during and after pregnancy.

"Don't smoke during pregnancy."

This study, led by Line Rode, MD, PhD, of the Department of Obstetrics at Copenhagen University Hospital in Denmark, looked at the links between quitting smoking, a woman's weight during and after pregnancy and her baby's weight.

The researchers studied 1,774 women who gave birth to single babies.

The women were classified based on whether they had smoked, not smoked or quit smoking during pregnancy.

They were also classified based on whether they smoked, did not smoke, had resumed smoking after having quit or had remained a quitter at one year after giving birth.

Then the researchers compared the women's weight during pregnancy and one year after giving birth. They also compared the weights of the women's babies at birth.

The researchers found that women appeared to gain a similar amount of weight up through 16 weeks of pregnancy regardless of whether they smoked, didn't smoke or had quit smoking.

However, at 37 weeks of pregnancy (close to full term), those who had quit smoking had gained about 4.4 extra pounds compared to those who didn't smoke at all.

In terms of the children's weight, 7.4 percent of the babies born to nonsmokers were below the 10th percentile for birth weight.

The percentage was similar in those who had quit smoking — 8 percent — but much higher in smokers at 21.7 percent.

After taking into account demographic and medical differences among the women, the researchers calculated that babies born to smokers were about 3.6 times more likely to be underweight (below the 10th percentile) compared to nonsmokers.

Yet those who had quit had a similar risk for having an underweight baby as those who had never smoked.

At one year after giving birth, the women who had quit smoking and stayed quit had about 5 pounds greater weight gain than nonsmokers had.

The researchers concluded that quitting smoking had an effect on women's weight gain both during and after pregnancy.

However, quitting also considerably reduced the risk of a mother's baby being born underweight.

This study was published in the September issue of Obstetrics and Gynecology.

Information on funding was unavailable. The authors declared no conflicts of interest.

Review Date: 
August 23, 2013
Last Updated:
August 26, 2013