Maternal Health-related Behaviors: The Moderating Effect of Pre-pregnancy Smoking on the Association Between Pre-pregnancy Folic Acid Intake and Breastfeeding Duration

Abstract Background There is limited research on the interaction between pre-pregnancy behaviours of folic acid intake and smoking, and breastfeeding duration. Pre-pregnancy folic acid intake and breastfeeding are health promoting behaviours benefiting mothers and infants, whereas smoking has adverse effects. This study aims to examine the association between maternal pre-pregnancy folic acid intake frequency and 3-month breastfeeding with further examination of the moderating influence of pre-pregnancy smoking. Methods A secondary data analysis was conducted using data from the 2016–2019 Pregnancy Risk Assessment and Monitoring System (n = 70,947 postpartum mothers). Results Overall, 28.5% did not breastfeed at least 3 months, 42.0% reported not taking folic acid pre-pregnancy, and 13.2% reported pre-pregnancy smoking. In the multivariable model, there was a significant interaction between pre-pregnancy smoking and folic acid intake on 3-month breastfeeding. For the subgroup of non-smokers, the odds of breastfeeding for at least 3 months were significantly higher among mothers who took folic acid (1 to 3 times per week, aOR 1.21, p = 0.001; 4 to 6 times per week aOR 1.74, p < 0.001; and daily aOR 1.25, p < 0.001; p-trend < 0.001) compared to those who did not take folic acid. Conclusions In the population-based study, pre-pregnancy folic acid intake was associated with higher odds of breastfeeding at least 3 months among women who did not smoke pre-pregnancy. Nurse-midwives and other healthcare professionals caring for women of childbearing age should encourage a positive health-promoting lifestyle before pregnancy, including folic acid intake and smoking abstinence, which may contribute to positive health behaviour of breastfeeding.