New research published on bmj today reports that addressing the problem of smoking during pregnancy may help to reduce the socioeconomic inequalities in stillbirths and infant deaths by as much as 30 to 40 percent.

Without a doubt smoking during pregnancy has been associated with stillbirth. In addition, infant deaths and smoking rates during pregnancy vary strikingly with socioeconomic position. In order to find out more, a team of researchers began the task of measuring the effects of smoking during pregnancy and on the social inequalities gap in stillbirths and infant deaths.

They assessed the records of 529,317 live singleton births and 2,699 stillbirths delivered at 24 to 44 weeks' gestation in Scotland from 1994 to 2003.

Information on smoking during the pregnancy was gathered. A deprivation score was designated using postcode data from the 2001 population census.

Findings showed that the most underprivileged mothers tended to be younger. They were more likely to smoke and to give birth to preterm or low birth weight babies. In the same way, the least deprived mothers were more likely to be older, non-smokers, and less likely to give birth to preterm or low birth weight babies.

The stillbirth rate increased from 3.8 per 1,000 in the least deprived group to 5.9 per 1,000 in the most deprived group. The rate of infant deaths increased from 3.2 per 1,000 in the least deprived group to 5.4 per 1,000 in the most deprived group.

In the most deprived category, stillbirths were 56 percent more likely and infant deaths were 72 percent more likely, compared with the least deprived category.

Smoking during pregnancy accounted for 38 percent of the inequality in stillbirths and 31 percent of the inequality in infant deaths. Women in the most deprived group were three times more likely to smoke during pregnancy than were those in the least deprived group.

In closing, the authors propose tackling smoking during pregnancy and also reducing infants' exposure to tobacco smoke in the postnatal environment. This will help reduce stillbirths and infant deaths in general, as well as to reduce the socioeconomic inequalities in stillbirths and infant deaths possibly by as much as 30 to 40 percent.

Nevertheless, they underline that taking action on smoking on its own is doubtfully sufficient. There is a need for other measures to improve the social circumstances, social support, and health of mothers and infants.

"Contribution of smoking during pregnancy to inequalities in stillbirth and infant death in Scotland 1994-2003: retrospective population based study using hospital maternity records"
Ron Gray, clinical epidemiologist, Sandra R Bonellie, lecturer in statistics, James Chalmers, consultant in public health medicine,Ian Greer, dean, Stephen Jarvis, emeritus professor, Jennifer J Kurinczuk, reader in perinatal epidemiology, Claire Williams, statistician
BMJ 2009; 339:b3754
doi:10.1136/bmj.b3754
bmj

Stephanie Brunner (B.A.)