Introduction:
Smoking is prohibited in cars if children under the age of 15 are present in Finland. Passive smoking exposure is also harmful to the developing fetus, and it increases the risk for complications during pregnancy. This study investigated the prevalence of smoking exposure of pregnant women and their newborns in cars and homes.

Material and Methods:
This study is part of The Central Satakunta Maternity and Child Health Clinic (KESALATU) Study which is a prospective cohort study in primary health care of the Satakunta region of Southwest Finland. 217 pregnant women were recruited during their first maternity clinic visit between 09/2016 and 12/2019. The participants filled in self-report questionnaires including detailed questions about their background and use of tobacco and other nicotine products. Smoking indoors and in cars were asked at 12 weeks of gestation and 6 weeks after the delivery with the following questions: “Is there smoking indoors in your home?” and “Is there smoking in the car while you are riding?”.

Results:
During the first trimester of pregnancy, 32/217 (14.8%) pregnant women and 60/217 (29.8%) partners were active smokers. No one reported smoking indoors at home during or after pregnancy. 7 (3.2%) reported that there were smoking in their car, of which 6 were smokers themselves. Only 1 pregnant non-smoker was exposed to smoking in the car. At 6 weeks after the delivery, 15/168 (8.9%) women and 41/164 (25.0%) partners were active smokers. Only 1 woman, a smoker, reported that there was smoking in their car after the delivery. The others who had reported smoking in the car during pregnancy (2 dropouts) reported that there was no smoking in their cars even 3/4 of them were smokers.

Conclusions:
No one was exposed to smoking indoors at home. Fortunately, very few pregnant women were exposed to smoking in the car, and majority of them were also smokers. After the delivery, only one reported smoking in the car, although the prevalence of parental smoking remained high.