Prenatal Secondhand Smoke Exposure and Birth Outcomes

Significance: Research linking prenatal secondhand smoke (SHS) exposure in nonsmoking women to adverse birth outcomes is limited. In 2006, the U. S. Surgeon General reported that there is no safe level of SHS exposure, and in fact, SHS exposure causes premature death in infants and adults.

Purpose: The purpose of this study is to analyze the relationship between level of prenatal SHS exposure and maternal/infant outcomes using hair nicotine analysis.

Methods: A cross-sectional, nonexperimental study with 210 mother-baby couplets showed hair nicotine to be a valid biomarker for prenatal SHS exposure.

Results: Nonsmoking women exposed to prenatal SHS (.35 to 2.09 ng/ml hair nicotine) were more likely to have maternal and infant complications; deliver babies that weigh less (306 grams: Kruskal-Wallis; X2(df=2) = 19.44 p <.0001); have decreased birth lengths (1.4 cm: X2(df=2) = 11.01; p = .004); and have shorter gestational periods by one week. Infants of nonsmoking SHS-exposed mothers were 2.4x; 3.5x; and 3.9x; more likely of experiencing newborn complications; being admitted to NICU; and being diagnosed with RDS than infants of nonsmoking, non-exposed mothers.

Public Health Implications: Social pressures have influenced many to view smoking during pregnancy in a negative context; however, this effect is often diminished after the birth of the infant. Increasing public awareness on the health effects of home exposure to SHS could extend awareness far beyond birth, and become a motivator for women and their families to remain smokefree.