A new study has come up with another reason for pregnant women not to smoke.
It seems that a mother's cigarette smoking increases the risk that her baby may be born with extra, webbed or missing fingers or toes.
According to a new study by doctors at the Children's Hospital of Philadelphia, although the overall risk of such abnormalities in fingers and toes is relatively low, just half a pack of cigarettes per day increases the risk to the baby by 29 percent, compared to non-smokers.
Because limbs develop very early in pregnancy, the effect may possibly occur even before a woman knows she is pregnant.
Benjamin Chang, M.D.,a pediatric plastic and reconstructive surgeon, the study leader and co-author Li-Xing Man, M.Sc., both of Children's Hospital and the University of Pennsylvania, reviewed the records of more than 6.8 million live births listed in the U.S. Natality database from 2001 and 2002.
This is one of the largest study of its kind, covering 84 percent of U.S. births.
The study population were placed into four groups: non-smokers; those who smoked one to ten cigarettes daily; 11 to 20 cigarettes daily; and 21 or more per day.
They found that women who smoked up to half a pack a day were 29 percent more likely to have babies with digital anomalies and women who smoked more than a pack of cigarettes a day during pregnancy were 78 percent more likely to have babies with digital anomalies.
The researchers found that of the total 6.8 million births, 5,171 children born with digital anomalies had mothers who smoked during pregnancy.
Limbs begin to develop between four and eight weeks of gestation and advance from a tiny nub to nearly fully formed fingers and toes.
Many women only discover they are pregnant during this period.