Objective: To investigate the feasibility and impact of integrating a cotinine-assisted smoking intervention programme with an existing antenatal maternal serum alpha-fetoprotein (AFP) screening service for open neural tube defects.
Design: A multisite randomized controlled trial.
Setting: 139 physician offices and clinic sites in Maine providing antenatal care.
Subjects: 2848 pregnant women who smoked 10 or more cigarettes daily, enrolled at between 15 and 20 weeks gestation, from a population base of approximately 18,000 pregnancies.
Interventions: The women were individually allocated at random to intervention or control groups within each centre at the time the serum sample was received for AFP measurement. The intervention group received an interpreted measurement of the serum cotinine, reported through the physician to the woman, along with a self-help smoking cessation booklet and a repeat serum cotinine measurement one month later, again interpreted and reported through the physician to the woman. Women in the control group received the usual anti-smoking advice provided by the antenatal care site and were not told of the study.
Main outcome measures: Birthweight, physician cooperation with study protocol (as measured by effectiveness in obtaining repeat serum samples for cotinine measurements).
Results: Pregnancy outcome data were available for 97% of the study population, including birthweight for 2700 singleton viable pregnancies. The smoking intervention programme led to a significant 66 g increase in mean birthweight (P = 0.03; 95% CI+9 to +123 g) and to a 30% reduction in the rate of low birthweight in pregnancies managed by the 70 physicians who secured the highest rate of obtaining repeat serum samples for cotinine measurements in their intervention group. Among the remaining 69 physicians, intervention had no detectable effect on birthweight.
Conclusion: A cotinine-assisted smoking intervention programme managed from a central location as an adjunct to a maternal serum AFP screening service can, with the cooperation of physicians responsible for antenatal care, lead to a significant and cost-effective reduction in the number of low birthweight babies. This programme is inexpensive, requires little extra effort, and does not need specially trained personnel.