Hyperemesis gravidarum and long‐term mortality: a population‐based cohort study

OBJECTIVE: To investigate whether exposure to hyperemesis gravidarum (HG) is associated with increased maternal long‐term mortality. DESIGN: Population‐based cohort study. SETTING: Medical Birth Registry of Norway (1967–2002) linked to the Cause of Death Registry. POPULATION: Women in Norway with singleton births in the period 1967–2002, with and without HG. Women were followed until 2009 or death. METHODS: Cox proportional hazard regression model was applied to estimate hazard ratios (HRs) with 95% confidence interval (CI). MAIN OUTCOME MEASURES: The primary outcome was all‐cause mortality during follow up. Secondary outcomes were cause‐specific mortality (cardiovascular mortality, deaths due to cancer, external causes or mental and behavioural disorders). RESULTS: Of 999 161 women with singleton births, 13 397 (1.3%) experienced HG. During a median follow up of 26 years (25 902 036 person‐years), 43 470 women died (4.4%). Women exposed to HG had a lower risk of long‐term all‐cause mortality compared with women without HG (crude HR 0.82; 95% CI 0.75–0.90). When adjusting for confounders, this reduction was no longer significant (adjusted HR 0.92; 95% CI 0.84–1.01). Women exposed to HG had a similar risk of cardiovascular death as women not exposed (adjusted HR 1.04; 95% CI 0.83–1.29), but a lower long‐term risk of death from cancer (adjusted HR 0.86; 95% CI 0.75–0.98). CONCLUSION: In this large population‐based cohort study, HG was not associated with an increased risk of long‐term all‐cause mortality. Women exposed to HG had no increase in mortality due to cardiovascular disease, but had a reduced risk of death from cancer. TWEETABLE ABSTRACT: Population‐based cohort study: Hyperemesis was not associated with an increased risk of long‐term mortality.