Background Smoking in pregnancy increases the risk of major adverse health outcomes for mothers and their offspring. The aim of this study was to describe socio-demographic differences in smoking before and during early pregnancy among women in England.

Methods Among 652,880 women with their first antenatal (booking) appointment recorded in the national Maternity Services Dataset between April 2018 and March 2019, 514,227 (78.8%) had valid data on all relevant variables and were included in analysis. Women reported their smoking status (including prior cessation), age and ethnicity. Level of deprivation was based on postcode and expressed as the Index of Multiple Deprivation. Descriptive analyses examined differences in smoking status by age, ethnicity and level of deprivation (deciles). Proportions were mutually adjusted for socio-demographic characteristics, and chi-square tests determined statistical significance.

Results Women had a mean age of 29.8y (SD 5.7), a median gestational age of 9.7 weeks at booking (interquartile range 8.4–11.4) and 35.6% were pregnant for the first time. Almost 1 in 4 women (23.5%) smoked 12 months before conception, 20.8% smoked around conception and 13.1% at booking. Smoking 12 months before conception was highly prevalent in women aged <20y (45.3%) and decreased to 16.5% in those aged ≥35y. The proportion who smoked before conception also decreased across level of deprivation, from 36.1% (most deprived areas) to 15.5% (least deprived). Asian (Chinese/South Asian/other Asian) (4.8%) and black women (10.1%) were less likely to smoke before conception compared with women of white (28.2%), mixed (24.3%) and other (14.0%) ethnicity. Among women who smoked before pregnancy, 14.5% quit during the 12 months before conception and 29.5% between conception and booking. Women aged ≥35y were nearly twice as likely to quit before conception as women aged <20y (17.0% vs 10.2%), but not more likely to quit in early pregnancy (28.6% vs 28.9%). Women living in the least deprived areas were three-times more likely to quit before conception than women in the most deprived areas (23.7% vs 7.8%), and twice as likely to quit in early pregnancy (41.3% vs 19.0%). All comparisons were significant at p<0.0001.

Conclusion Smoking before and during pregnancy remains common among women in England, and socio-demographic differences in smoking cessation are most pronounced before pregnancy. This suggests targeted efforts are needed to reduce smoking uptake and/or increase cessation support, particularly for younger women of reproductive age, those living in the most deprived areas, and women of white and mixed ethnicity.