Assisted reproductive technology and severe postpartum haemorrhage: a case-control study.

OBJECTIVE: To investigate the association between assisted reproductive technology and severe postpartum haemorrhage. DESIGN: Case-control study. SETTING: The study was conducted in Norway; Division of Gynaecology and Obstetrics at Oslo University Hospital and Department of Obstetrics and Gynaecology at Drammen Hospital. POPULATION: A source population including all women admitted for delivery at Oslo University Hospital and Drammen Hospital during the time period 1 January 2008 to 31 December 2011. The study population consisted of all cases of severe postpartum haemorrhage (n = 1064) and a random sample of controls (n = 2059). METHODS: We used an explanatory strategy in the analysis, with multivariable logistic regression. MAIN OUTCOME MEASURES: Severe postpartum haemorrhage; defined as blood loss ≥1500 ml or need for blood transfusion. RESULTS: Assisted reproductive technology was associated with an increased risk of severe postpartum haemorrhage (crude OR = 2.92; 95% CI 2.18-3.92, P < 0.001). Mode of delivery and anticoagulant medication had significant confounding effects. Strong interaction was found for multiple pregnancies. After adjusting for confounding and interaction, an increased risk was observed both in the strata of multiple pregnancies (adjusted OR = 7.00, 95% CI 2.70-18.12, P < 0.001), and in the strata of single gestation (adjusted OR = 1.58, 95% CI 1.12-2.24, P = 0.010). CONCLUSIONS: Our findings warrant an increased awareness of the risk of severe postpartum haemorrhage in women conceiving with assisted reproductive technology. Furthermore, the high risk of severe postpartum haemorrhage in the presence of a twin or triplet pregnancy is an additional argument for single embryo transfer. TWEETABLE ABSTRACT: Assisted reproductive technology is associated with an increased risk of severe postpartum haemorrhage.