Question

Does second-hand smoke increase the risk of a low weight birth? A baby is “low birth weight” if it weighs less than 5.5 pounds at birth. According to the National Center of Health Statistics, about 7.8% of all babies born in the U.S. are categorized as low birth weight.

Answer 1

Second-hand smoke may increase the risk of a low weight birth, if there is a positive correlation between these two events. But we don't have enough information to prove that.