The authors reviewed results of two studies sent to patients at maternity facilities throughout Japan in 2002 and in 2006. The patients were asked whether they were current smokers, their exposures to environmental smoke, sleep status, and demographic information.
The questionnaires included questions about sleep status during the previous month, asking whether the patients had subjective insufficient sleep, difficulty in initiating sleep, difficulty maintaining sleep, early-morning awakening, short sleep duration, excessive daytime sleepiness, and loud snoring or uncomfortable breathing causing nocturnal awakening (the latter was included only in the 2006 survey).
There were a total of 16,396 respondents to the 2002 survey and 19,386 to the 2006 iteration.
The authors found that 9.9% of pregnant women in the 2002 survey smoked during their pregnancies, compared with 7.8% in 2006. Environmental smoke exposure also decline between surveys, from 62.1% of pregnant women in 2002, to 52.7% in 2006. In both studies, husbands were the primary source of exposure for 80% or more of the women.