Early Life Origins of Adult Disease and Maternal Smoking During Pregnancy

Abstract

Johnson and Shoeni examined the relation between low birth weight (LBW) and childhood family socioeconomic disadvantage and disease onset in adulthood.1 They report that LBW independently predicted asthma, hypertension, diabetes, and cardiovascular diseases by age 50 years. Disease prevalence was influenced also by childhood socioeconomic (SES) status. They conclude that these findings are consistent with the fetal origins hypothesis, which posits that adverse in utero influences increases the risk of disease later in life. We would like to stress the likely mediating effect of maternal smoking during pregnancy. In the study by Johnson and Shoeni, the smoking variable, parental smoking, increased disease risk in adulthood in univariate but not in multivariate analyses probably because it lacks specification (i.e., it did not distinguish which parent was a smoker and whether the mother smoked or not during her pregnancy). Maternal smoking during pregnancy is known to be associated with negative prenatal and birth consequences and LBW.2,3 Maternal smoking during pregnancy is an independent risk factor for obesity,4–6 type 2 diabetes mellitus,4 high blood pressure,7 and smoking,2 all known risk factors for cardiovascular disorders. Intrauterine exposure to maternal smoking is also associated with asthma even in offspring of nonsmoking mothers but who themselves were exposed in utero to maternal smoking,8 suggesting that smoking may induce genotoxicity. Moreover, maternal smoking during pregnancy dose-dependently increases the likelihood of psychiatric disorders and all cause mortality up to age 20 years.9 In addition, smoking, and in particular smoking during pregnancy, is known to be associated with low SES.10 Maternal smoking during pregnancy is the most important modifiable adverse fetal exposure risk.3 It is likely to mediate a significant part of the relation between LBW and disease onset in adulthood that was reported by Johnson and Schoeni.1 Full eradication of smoking among pregnant women may reduce the onset of several diseases in the next generation.