Effects of Purchase Restrictions on Smoking During Pregnancy: An Analysis of US Birth Records

Introduction In December 2019, the minimum legal sales age (MLSA) for tobacco products in the United States was raised from 18 to 21 years as a measure of preventing smoking initiation. Smoking during pregnancy, which causes maternal, fetal, and infant morbidity and mortality, is a major public health concern. We first study the effects of purchase restrictions on smoking during different stages of pregnancy covering the entire United States and using the records of all live births during 2014-2018 by birthing people aged 18-21 years. Aims and Methods Our identification strategy utilizes the variation in the MLSA of tobacco products over time and across counties in the United States during 2014-2018 using a two-way fixed effects model, modified to accommodate a partially observable treatment indicator. Results The results show that 37.4% of potential smokers in our study population would have been prevented from smoking before pregnancy, 50.5% during the first trimester, 53.4% during the second trimester, and 14.8% during the third trimester if the law prevented selling tobacco products to them in the locality they live. A purchase restriction is estimated to cause the smoking intensity of those who smoke, the intensive margin, to drop by 5.4% before pregnancy, 10.4% during the first trimester, 14.8% during the second trimester, and 5.2% during the third trimester. Conclusions Our results show that purchase restrictions are highly effective in preventing smoking among birthing people in the 18-21 years age group. The effect on smoking prevalence during the first and second trimesters is more pronounced. Implications Many countries around the world have recently tightened age-based purchase restriction policies as a tobacco control measure. We first study the effects of purchase restrictions on smoking during different stages of pregnancy using the birth records of all pregnancies in the United States by birthing people aged 18-21 years during 2014-2018. The study utilizes the variation in the MLSA of tobacco products over time and across counties during that period. Our results show that purchase restrictions are highly effective in preventing smoking among birthing people in the 18-21 years age group.