Background:
Secondhand smoke (SHS) exposure during pregnancy is associated with complications for the pregnant women, the fetus and the newborn that can be very severe. Uruguay and Argentina still have a high prevalence of smoking and national surveys show a high prevalence of SHS exposure in the general population in spite of current legislation. Our objective was to assess SHS exposure among non smoking pregnant women in Argentina and Uruguay.

Methods:
Data were collected from October 2011 to November 2013 as part two-arm parallel cluster randomized trial with baseline and follow-up cross sectional measurements conducted in 10 clusters in Buenos Aires and 10 in Montevideo. During the first 48 hours after delivery, we surveyed pregnant women using a validated questionnaire about tobacco use and SHS exposure at home, at work and indoors in general during pregnancy.

Results:
We surveyed 3039 women in Uruguay and 3799 in Argentina. Overall, 1877 (61.7%) in Uruguay and 2786 (73.3% in Argentina) were non smokers. Among non smoking pregnant women, 37.0% in Argentina and 36.7% in Uruguay had a partner who smoked. Also, 44.4% in Argentina and 47.1% in Uruguay lived with at least one smoker. Overall, 47.7% in Argentina and 48.8% in Uruguay were exposed to secondhand smoke at home (live with at least one smoker/has a partner who smoke and do not have smoke free home rule). Among those who had a job, 13.8% in Argentina and 9.3% in Uruguay were exposed to SHS at work.

Conclusions:
SHS exposure in Argentina and Uruguay is very high during pregnancy, particularly at home. As legislation cannot impose smoke free homes, health care professionals should take advantage of the prenatal care visits to routinely ask about SHS exposure and recommend women to avoid exposure and to implement 100% smoke free homes.