- Maternal smoking was associated with a lower risk for type 1 diabetes (T1D) incidence during childhood.
Why this matters
- Maternal smoking during pregnancy is not recommended but the underlying mechanism associated with a reduction in the T1D needs to be further investigated.
- A whole-of-population study of 286,058 children born between 1999 and 2013, contributed to 2,200,252 person-years of data.
- Funding: The National Health and Medical Research Council of Australia’s Partnership Project Grant and Centre for Research Excellence.
- Of 286,058 children, 557 were diagnosed with T1D (incidence, 25.3 per 100,000 person-years) and 62,216 were born to mothers who smoked during pregnancy.
- Compared with non-smokers, children who were exposed to maternal smoking during the first or second half of pregnancy had a 6% higher risk for childhood T1D incidence (adjusted HR [aHR], 1.06; 95% CI, 0.73-1.55).
- Compared with the unexposed group, the incidence of T1D was lower in children exposed to consistent prenatal (aHR, 0.76; 95% CI, 0.58-0.99) and any maternal smoking (aHR, 0.84; 95% CI, 0.67-1.08) in pregnancy.
- The negative control outcome analysis indicated residual confounding in the association between prenatal smoking and type 1 diabetes.
- In the E-value analysis, unmeasured confounder associated with prenatal smoking and childhood T1D was 1.67, which could negate the observed effect.
- Risk of unmeasured confounding.