Secondhand smoke exposure during pregnancy in developing countries
on 23 November 2018 Research Midwives Magazine Smoking
Exposure to tobacco smoke during pregnancy poses serious but avoidable risk to fetal development leading to stillbirth, congenital malformations and low birthweight.
While most pregnant women don’t smoke, many may inhale secondhand smoke (SHS) involuntarily. This study estimates the extent to which pregnant women living in low- and middle-income countries (LMIC) are exposed to SHS. It also predicts the proportion of stillbirths that could be attributable to SHS exposure during pregnancy.
Demographic Health Survey data collected in 30 LMIC, between 2008 and 2013, were analysed. Conducted at five-year intervals, these are nationally representative cross-sectional household surveys. Using a questionnaire, surveyors collect information on the socio-demographic characteristics, health and health behaviours of the residents. Women who were pregnant at the time of survey (denominator) and among them those who were exposed to SHS (numerator) were identified.
Estimates of SHS exposure during pregnancy varied considerably from country to country, with a range from 7% in Nigeria to 81% in Armenia. In eight countries, more than 40% of all pregnant women inhaled SHS often on a daily basis. The researchers also found that the extent of SHS exposure among pregnant women was very similar to the extent of smoking among males in these countries. The impact of this level of SHS exposure was also estimated to cause significant fetal harm. For example, in Indonesia where almost two-thirds of all male adults smoke, up to 14% of all stillbirths could be a consequence of SHS exposure. In Pakistan, SHS exposure might have led to almost 17,000 stillbirths in a year.
In all 30 countries included in this analysis, more women were exposed to SHS during pregnancy than those who smoke actively in their pregnancy. In 13 of these countries, exposure to SHS was 10 times higher than active smoking during pregnancy. These estimates suggest that SHS exposure is much more heavily implicated in the number of stillbirths than active smoking. For example, in Pakistan, only 1% of stillbirths were attributed to women actively smoking during pregnancy, but for SHS the figure was 7%.
In routine antenatal care, assessing and addressing SHS exposure has received a lower priority than active smoking. This study offers comprehensive estimates of SHS exposure among pregnant women living in LMIC. It also highlights that the population level impact of SHS exposure on fetal development may even be bigger than active smoking. Therefore, the assessment of SHS exposure and advice on how to address it should be integrated within antenatal care.
Kamran Siddiqi is professor in global public health at the University of York
Reece S, Morgan C, Parascandola M, Siddiqi K. (2018) Secondhand smoke exposure during pregnancy: a cross-sectional analysis of data from Demographic and Health Survey from 30 low-income and middle-income countries. Tobacco Control doi: 10.1136/tobaccocontrol-2018-054288.