Ultrasound surveillance of fetal growth and wellbeing in maternal occupational tobacco handling – A cohort study

Introduction: Tobacco exposure during pregnancy has a negative influence on fetal growth. Maternal smoking causes placental vaso­constriction and fetal growth restriction (FGR). In India, the tobacco industry employs women to hand roll cigarettes called bidis. A bidi roller handles 120 g of tobacco and therefore 3 g of nicotine per day. Aim: To evaluate the effect of occupational tobacco handling by pregnant women on fetal growth and wellbeing. Methods: In this cohort study, 177 pregnant bidi rollers (exposed cohort) and 354 pregnant non-rollers (unexposed cohort) were followed up from 18-22 weeks of pregnancy until delivery with fetal sonogram and Doppler. Fetal surveillance data (including fetal biometry, Doppler indices, amniotic fluid index, biophysical profile and placentation) were recorded and compared. Maternal nicotine absorption was quantified by serum cotinine. Intergroup differences and relative risk (RR) were determined by Chi-square test (or Fisher exact when the count was ≤ 5), and adjusted odds ratio (OR) by binary logistic regression. Intrauterine growth trend was plotted. Results: Fetal surveillance results were ab­normal in 37.9% of the tobacco-exposed group, with a RR of 1.6 (p = 0.001) and adjusted OR of 1.8 (p = 0.005) in comparison with the unex­posed group. Nicotine absorption was evident in 28.4% of the bidi rollers that had abnormal fetal surveillance results. The mean estimated fetal weight and head circumference demonstrated a sustained deceleration, starting at 28-30 weeks of gestation, in the exposed group. Doppler data suggested fetal adaptation to maintain cerebral circulation. We found a higher frequency of oligohydramnios (statistically significant), pla­cental abruption (not statistically significant), and placenta previa (not statistically significant) in the tobacco-exposed group. Conclusions: Occupational tobacco handling in bidi rollers resulted in early-onset symmetric FGR and compromised wellbeing. Pregnant women with any form of tobacco exposure require vigilant fetal surveillance.