Purpose: To determine the rate of severe maternal morbidity related to delivery by delivery mode and to assess if the impact of studied risk factors varies by delivery mode.
Methods: A register-based study including all women having singleton delivery in Finland in 2007-2011, n = 292,253, data derived from the Finnish Medical Birth Registry and Hospital Discharge Registry. Diagnoses and interventions indicating a severe maternal complication were searched and the mode of delivery was assessed by data linkage. The impact of obesity, maternal age 35 years or more, pre-eclampsia and insulin dependent diabetes on severe maternal morbidity (all severe complications, severe infections and severe) was studied in each mode of delivery and calculated as Odds ratios.
Results: The overall incidence of severe complications was 12.8/1,000 deliveries. The total complication rate was lowest in vaginal deliveries (VD) in all risk groups. Obesity increased the risk for all severe complications and severe infections in the total population, but not significantly in specific delivery modes. Age increased the risk of hemorrhage in VD. Pre-eclampsia increased the risk for hemorrhage in all deliveries except elective CS. In women with pre-eclampsia, overall morbidity was similar in VD, attempted VD and elective CS. The presence of any studied risk factor increased the risk for complications within the risk groups by the high proportion of emergency CS performed.
Conclusions: An attempt of VD is the safest way to deliver even for high-risk women with the exception of women with pre-eclampsia, who had a similar risk in an attempt of VD and elective CS.