Type of Labour in the First Pregnancy and Cumulative Maternal Morbidity.

Objective: To estimate cumulative maternal morbidity among women who delivered at term in their first pregnancy on the basis of type of labour in the first pregnancy.

Methods: Using a 25-year population-based cohort (1988 to 2012) derived from the Nova Scotia Atlee Perinatal Database, we determined the type of labour in successive pregnancies in low-risk, nulliparous women at term in their first pregnancy (who had at least one subsequent pregnancy), and the maternal outcomes in subsequent deliveries based on the type of labour in the first pregnancy.

Results: A total of 36 871 pregnancies satisfied inclusion and exclusion criteria, 1346 of which were delivered by Caesarean section without labour in the first pregnancy. Rates of most adverse maternal outcomes were low (≤1%). The type of labour in the first pregnancy influenced the subsequent risk of postpartum hemorrhage and blood transfusion, and the risks increased with successive deliveries when labours were spontaneous in onset or were induced. The risks for abnormal placentation were low with subsequent deliveries, including following CS without labour in the first pregnancy, and risks for overall severe maternal morbidity were less than 10% for all subsequent deliveries.

Conclusion: The absolute risks for severe maternal morbidity outcomes in a population of women without a high number of subsequent pregnancies were small (regardless of type of labour in the first pregnancy); this provides important information for women, families, and caregivers when considering pregnancy outcomes related to type of labour.