Impact of maternal smoking on early childhood health: a retrospective cohort linked dataset analysis of 697 003 children born in Scotland 1997-2009.

Objective: Smoking during pregnancy is associated with adverse health impacts on mother and child. We used a large linked Scottish dataset to produce contemporary estimates of the impact on child health, particularly hospitalisation.

Design: Retrospective cohort study linking birth, death, maternity, infant health, child health surveillance and admission records. We examined the association between smoking status at maternity booking and pregnancy outcomes, hospital admission and death during the first 5 years of life. Models were adjusted for maternal age, socioeconomic status, infant feeding, country of birth, sex, parity and delivery mode. We calculated population attributable fraction (PAF) for each outcome.

Setting: Scotland, UK.

Participants: Singleton births between 1997 and 2009 (n=697 003) followed to March 2012.

Results: 332 386 children had at least one admission by 31 March 2012. There were 56 588 born small for gestational age, 40 492 prematurely and 1074 postneonatal deaths. Within the first 5 years of life, 56 615 children had at least one admission for acute respiratory infections, 24 088 for bronchiolitis and 7549 for asthma. Maternal smoking significantly increased admission for acute respiratory infections (adjusted HR 1.29, 95% CI 1.25 to 1.34, PAF 6.7%) and bronchiolitis (HR 1.43, 95% CI 1.38 to 1.48 under 1 year, PAF 10.1%), asthma (HR 1.29, 95% CI 1.22 to 1.37 age 1-5 years, PAF 7.1%) and bacterial meningitis (HR 1.49, 95% CI 1.30 to 1.71, PAF 11.8%) age 0-5 years. Neonatal mortality (adjusted OR 1.32, 95% CI 1.17 to 1.49, PAF 6.7%), postneonatal mortality (OR 2.18, 95% CI 1.87 to 2.53, PAF 22.3%), small for gestational age (OR 2.67, 95% CI 2.62 to 2.73, PAF 27.5%) and prematurity (OR 1.41, 95% CI 1.37 to 1.44, PAF 8.8%) were higher among the offspring of smokers.

Conclusion: Smoking during pregnancy causes significant ill health and death among children born in Scotland. These findings support continued investment to reduce smoking among women before, during and after pregnancy as 50% of women will go on to have further children.