Pregnancy and post-partum tuberculosis: a nationwide register-based case-control study, Denmark, 1990 to 2018

BackgroundPregnancy increases the risk of tuberculosis (TB), however, data on TB epidemiology in pregnant women are limited.AimTo guide possible interventions, we analysed risk factors for TB in pregnant and post-partum women.MethodsWe conducted a nationwide retrospective register-based case-control study from January 1990 to December 2018 in Denmark. Cases were women diagnosed with TB during their pregnancy or in the post-partum period. We selected two control groups: pregnant or post-partum women without TB, and non-pregnant women with TB. Differences were assessed by chi-squared or Fisher's exact test. Risk factors for TB were identified through logistic regression and estimated by odds ratio (OR).ResultsWe identified 392 cases, including 286 pregnant and 106 post-partum women. Most were migrants (n = 366; 93%) with a shorter median time spent in Denmark (2.74 years; interquartile range (IQR): 1.52-4.64) than non-pregnant TB controls (3.98 years; IQR: 1.43-8.51). Cases less likely had a Charlson comorbidity index ≥ 2compared with non-pregnant TB controls (p < 0.0001), and had no increased risk of severe disease (p = 0.847). Migrants from other World Health Organization regions than Europe, especially Africa (OR: 187; 95%CI: 125-281) had persistently higher odds of TB.ConclusionsIn Denmark, the risk of TB in pregnant and post-partum women is increased in migrant women who have stayed in the country a median time of approximately 3 years. We recommend increased focus on TB risk during pregnancy and suggest evaluating targeted TB screening of selected at-risk pregnant women to promote early case finding and prevent TB among mothers and their newborn children.