Maternal smoking and multiple sclerosis risk in offspring: A further clue of prenatal environmental triggers

Multiple sclerosis (MS) is a complex, inflammatory, and neurodegenerative disease of the central nervous system, whose exact cause is not fully understood. Among potential risk factors, there is consistent evidence indicating that active and passive smoking increases the risk of both the development of MS and a more aggressive disease course after onset.1 On the contrary, the potential effects of smoking during pregnancy on the risk of MS in offspring have not yet been clarified. Smoking during pregnancy has been shown to influence fetal development, including that of the nervous system and immune system,2 and could therefore interfere with the normal immunological containment of other MS triggers, such as Epstein–Barr virus infection. A few previous studies on this topic obtained conflicting evidence of an association with higher risk of developing MS, mainly due to potential methodological limitations, such as small sample size and both recall and selection biases.