Risk of tuberculosis in pregnancy: a national, primary care-based cohort and self-controlled case series study

Tuberculosis (TB) disease adversely affects mother and child, and strategies to control TB in this group are important. The aim of this study was to analyze the epidemiology of TB in pregnancy, and to establish whether pregnancy is an independent risk factor for TB.

The United Kingdom-wide cohort study was based on the General Practitioner Research Database (GPRD), enrolling all women with pregnancies between 1996 and 2008. Incidence rates and incidence rate ratios (IRRs) of TB events during pregnancy, 6 months postpartum, and outside pregnancy were calculated and compared by Poisson regression. A nested self-controlled case series compared the risk of TB in these periods, adjusting for individual and time-bound confounders.

The crude TB rate for the combined pregnancy and postpartum period was 15.4 per 100,000 person-years, significantly higher than outside of pregnancy (9.1 per 100,000 person-years; P = 0.02). Adjusting for age, region, and socioeconomic status the postpartum TB risk was significantly higher than outside pregnancy (IRR, 1.95; 95% confidence interval [CI], 1.24-3.07), whereas there was no significant increase during pregnancy (IRR, 1.29; 95% CI, 0.82-2.03). These observations were confirmed in the self-controlled case series (IRR, 1.62; 95% CI, 1.01-2.58 and IRR, 1.03; 95% CI, 0.64-1.65, respectively).

The incidence of TB diagnosis is significantly increased postpartum. Although we did not find an increase during pregnancy, the postpartum incidence may reflect an increase during pregnancy given diagnostic, immunological and administrative delays. Clinicians' awareness should be improved and the effectiveness of public health policy measures such as targeted screening of pregnant and postpartum women in high-risk groups should be evaluated.