1. Association Between Maternal Smoking and Breastfeeding at 10 Weeks Kenneth D. Rosenberg, MD, MPH Zhiwei Yu, MPH Alfredo P. Sandoval, MS, MBA Oregon Office of Family Health Portland, Oregon 8 th Annual MCH Epidemiology Conference December 13, 2002 Clearwater Beach, Florida

2. Introduction Maternal smoking: Associated with decreased breastfeeding Hakansson et al. (Scand J Prim Health Care 1992;10:60-65): 44% longer. Horta et al. (Am J Epidemiol 1997;146:1128- 1133): smoking not associated with BF initiation but associated with BF duration.

3. Background Maternal smoking: before, during or after pregnancy? PRAMS: sample size asks about smoking before, during and after pregnancy

4. Methods I Oregon PRAMS Stratified random sample of Oregon resident mothers Year 1: babies born 8/1/98-8/9/99. Weighted for oversampling, nonresponse and noncoverage. Duration of breastfeeding: "For how many weeks did you breast-feed your new baby?" Over 99% completed: after baby 10 weeks old.

5. Methods II PRAMS: Smoking before, during and after pregnancy. Before = in the 3 months before pregnancy During = in the last 3 months of pregnancy After = smoking now (10-26 weeks after birth)

6. Results I Response rate: 1867/2919 = 64.0% 83.6% of women initiated breastfeeding. 59.5% of women were still breastfeeding at 10 weeks old.

7. Results II Strength of Association Between Time of Maternal Smoking and Not Breastfeeding at 10 Weeks (multivariate) Time of Smoking ORa 95% CI Before Pregnancy* Smokers 2.17 1.47, 3.23 During Pregnancy** Smokers 1.85 1.11, 3.13 After Pregnancy*** Smokers 2.56 1.64, 4.00 For all 3 times: reference is non-smokers * Before = in the 3 months before pregnancy ** During = in the last 3 months of pregnancy *** After = smoking now (10-26 weeks after birth)

8. Conclusions Maternal smoking: associated with decreased breastfeeding Parallel work: Letson GW, Rosenberg KD and Wu L. Association between smoking during pregnancy and breastfeeding at about two weeks of age in Oregon, 1998. Journal of Human Lactation. 2002;18:368-372 Maternal exposure to nicotine decreases breast milk output. Smoking mothers may have lower milk output and lower prolactin levels than nonsmoking mothers

9. Public Health Implications Assist pregnant women who wish to stop smoking Helping mothers to quit smoking: should increase breastfeeding duration Breastfeeding support programs