Background
There is extensive evidence showing that smoking during pregnancy can have devastating consequences for mothers and their babies. It has been associated with a number of adverse outcomes, including miscarriage, stillbirth, preterm birth, neonatal complications, and low birth weight.
Women known to be smokers at the time of delivery
The prevalence of smoking during pregnancy has been decreasing over time. Between 2006/07 and 2015/16, the percentage of women who were known to be smokers at the time of delivery decreased steadily from 16% to 11%. The target to reduce the percentage of women who smoke during pregnancy to 11% or less by the end of 2015 was met.
Since then, the reduction in smoking rates among pregnant women has slowed, with only a 2.2 percentage point decrease between 2015/16 and 2022/23.
In 2022/23, 8.8% of women were known to be smokers at the time of delivery, higher than the target set by the Department of Health in its tobacco control plan for England, leaving the 6% target unachieved in the proposed timeframe.
About this data
This indicator uses data from NHS Digital's statistics on women's smoking status at the time of delivery in England. The percentage calculation for women who were known to be smokers at time of delivery previously included women with an unknown smoking status in the denominator, i.e. the total number of maternities. This meant that women with an unknown smoking status were being treated the same way as non-smokers. Thus, poor data quality (i.e. having a lot of unknowns) could have masked poor performance.
From April 2017, the methodology used to calculate the proportion of women smoking at the time of delivery changed to exclude women with an unknown smoking status from the denominator. Data for all years was recalculated to fit this new definition.
Percentage of mothers smoking at the time of delivery (excluding unknowns) = 100 x number of mothers recorded as smoking at time of delivery / (number of mothers recorded as smoking at time of delivery + number of mothers recorded as not smoking at time of delivery).
Women known to be smokers at the time of delivery were defined as pregnant women who self-reported that they were smokers (inclusive of cigarettes and tobacco, but not inclusive of non-combustible nicotine products). Women known to be non-smokers at the time of delivery were defined as pregnant women who reported smoking no cigarettes (at all) at the time of delivery. Women whose smoking status was not known at the time of delivery were defined as pregnant women who self-reported that they were non-smokers. Perceptions of social acceptability may have caused women to report being a non-smoker.
For more information, please see NHS Digital's appendices and data quality statement.