PP.18 Caesarean Section and Time to Next Birth, Ectopic Pregnancy, Miscarriage or Stillbirth-A Danish Register-Based Study: Abstract PP.18 Table

Abstract

Study question: Does a primary caesarean section increase the risk of subsequent stillbirth, miscarriage, ectopic pregnancy or the waiting time to next birth compared to a primary vaginal delivery? Summary answer: Aprimary caesarean section was associated with an increased risk of stillbirth and a longer pregnancy interval in the subsequent delivery compared to women with a primary vaginal delivery. No increased risk of subsequent ectopic pregnancy or miscarriage was found in this cohort. What is known already: Caesarean section rates are at the highest ever recorded worldwide and the benefits and risks of this surgery are largely disputed. Particularly, the impact on a woman's subsequent fertility, where research to date is limited, conflicting and of poor methodological quality. Study design, size, duration: Danish population-based registry cohort study using the Danish Civil Registration System data. All births during the years 1982-2010. A cohort of 833,162 primiparous women in total. Participants/materials, setting, methods: Exposed: all women with a primary Caesarean. Comparison: all women with a primary vaginal delivery. The cohortwas followedfrom the index birth until the next birth or censoring by death, emigration or study end (31/12/2010). Analysis included stratified Cox regression models using SAS version 9.2. Main results and the role of chance Limitations, reason for caution: The time to next birth may be biased (women may have reached desired family size, use of contraception, etc.). Details on the causes of stillbirth were not available and research to date has shown an increased risk of unexplained stillbirth in women with a prior caesarean. Wider implications of the findings: With one in six couples seeking fertility treatment, the impact of Caesarean sections on subsequent deliveries could have social, clinical and wider public health implications. From the findings it is hoped that women will be better educated and make an informed decision with their clinican regarding mode of delivery.