Wang X, et al. - In order to mitigate known hazards of smoking, women who smoke may switch to vaping (use electronic cigarettes, e-cigs; these contain nicotine but either eliminates or greatly diminishes exposure to the combustion products of tobacco) around pregnancy. Researchers here studied a US-wide representative sample of 31,973 live singleton births in 2016; of this sample, 5,029 (14%) mothers reported to have exclusively smoked tobacco (“sole smokers”) and 976 (3%) reported to have used both tobacco and e-cigs (“dual-users”) in the three months before pregnancy. Either only electronic cigarette use or dual-use was reported in late pregnancy in about 1% of women. Self-reported late-pregnancy vapers and dual-users vs non-users had a similar risk of preterm births but had a higher risk of restricted fetal growth births.