The invisible enemy: a systematic review and meta-analysis of maternal smokeless tobacco use as a risk factor for low birth weight

Abstract

Abstract Introduction Smokeless tobacco use is a growing public health concern, with potential adverse implications for foetal outcomes if consumed during pregnancy. Birth weight is an important predictive measure for health outcomes of a child throughout their lifespan, from infancy through to adulthood. Although the association between maternal smoking and reduction in birth weight of infants has been studied extensively, it is unclear whether smokeless tobacco has similar effects. Hence, this review was conducted to determine whether an association exists between maternal smokeless tobacco consumption during pregnancy and birth weight of infants. Aims and Methods Systematic literature search was performed in Medline (via PubMed), Embase, Scopus, and CINAHL with no restrictions on language or time until January 2023. All observational studies (case control, cohort and cross sectional) that examined the relationship between maternal smokeless tobacco use and low birth weight of infants were eligible for inclusion. The methodological quality of included studies was assessed using the Newcastle Ottawa Scale. Results Thirty-one studies were eligible for the review, including twenty-seven cohort studies, two case-control and two cross-sectional studies. These studies examined various forms of smokeless tobacco use including khat, betel/areca nut, mishri, snuff, iqmik and pituri. A statistically significant association between use of smokeless tobacco and low birth weight was reported in thirteen studies. An additional eleven studies reported a statistically significant reduction in mean birth weight in maternal smokeless tobacco users. Meta-analysis using a random effects model showed that there was a statistically significant association (OR = 1.91 [1.38, 2.65], P < 0.00001); between maternal smokeless tobacco use during pregnancy and low birth weight. Subgroup analysis found a significant association between maternal mishri consumption during pregnancy and low birth weight (OR = 10.98 [2.03, 59.34], P < 0.05), but not betel nut, betel quid or khat. Conclusions This review found that there is a significant association between maternal smokeless tobacco use and low birth weight of infants, as well as reduction in mean birth weight independent of confounding variables. It is suggested that maternal use of smokeless tobacco should receive specific attention as a part of routine prenatal care. Implications The results of this study highlight the need for further preventive public health campaigns to create awareness about the detrimental effects of smokeless tobacco on foetal outcomes patient education by healthcare workers in the primary care setting will aid in promoting smokeless tobacco cessation prior to pregnancy.