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

Abstract

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.

Keywords: Cancer; cardiovascular disease; cohort study; hyperemesis gravidarum; long-term mortality.