A Clustered Randomized Controlled Trial to Reduce Secondhand Smoke Exposure Among Nonsmoking Pregnant Women in Sichuan Province, China.

Abstract

Nonsmoking pregnant women in China have significant exposure to secondhand smoke (SHS). Few interventions have focused on pregnant women reducing their SHS exposure. This clustered randomized controlled trial, conducted at eight hospitals in Sichuan, China, compared a prenatal health education intervention with usual clinical care as a control. The primary outcome was self-reported "no SHS exposure" before and 3 months after birth. The intervention consisted of three large group educational sessions, standardized clinician advice, brief monthly follow-up calls, and educational materials and resources. A random sample of participants was biochemically validated before birth with hair nicotine, a long-term biomarker of smoke exposure. Overall, 1181 participants were randomized to intervention (n = 526) and control (n = 655) groups. More participants in the intervention group than the control group reported no SHS exposure 3 months after birth (Total: 77.9% vs. 52.6%, P < .001; Home: 81.2% vs. 53.3%, P < .001). The intervention group also had greater changes in improved smoke-free homes and SHS knowledge and attitudes. Controlling for covariates, the intervention group was less likely to report SHS exposure than the control group (Total: OR = 0.47, 95% CI = 0.31 to 0.71; Home: OR = 0.33, 95% CI = 0.21 to 0.53), and this effect was sustained 3 months after birth. The adjusted log concentration of hair nicotine for the intervention group decreased by 0.28 log µg/g more than the control group. Our smoke-free health education intervention for nonsmoking pregnant women significantly reduced SHS exposure before and after birth. This intervention model can become part of a standard protocol for the care of pregnant women in hospital settings.