CUMULATIVE SECOND LIVE BIRTH IN A RECURRENT PREGNANCY LOSS POPULATION: PROGNOSTIC FACTORS AND IMPACT OF OTHER ADVERSE OBSTETRIC OUTCOMES.

To investigate the cumulative rate of a second live birth among a primary recurrent pregnancy loss (RPL) population compared to individuals without RPL and to evaluate the impact of any added adverse obstetric outcomes on the odds of having a second live birth. This was a retrospective population-based observational study analyzing data from the British Columbia Perinatal Data Registry (BCPDR), Canada. Women 15 to 45 years old who had their first live birth between 2000 – 2010 and reported at least one miscarriage were included. They were followed up until March 31st, 2018 or 49 years old, whichever came first. Primary RPL was defined as ≥ 2 pregnancy losses before 20 weeks’ gestation occurring before the first live birth. The study population was stratified into two cohorts, each cohort was divided into RPL and non-RPL groups. Cohort I (n = 166,426) included patients whose obstetric history included only pregnancy losses. Cohort II (n = 31,893) included patients with pregnancy losses and other adverse obstetric outcomes e.g., ectopic and molar pregnancies, pregnancy termination and stillbirth. Kaplan-Meier cumulative incidence curves with Grey’s tests were used to calculate and compare the unadjusted cumulative birth rates between RPL and non-RPL groups in each cohort. Adjusted Cox proportional hazards model controlling for confounders at first delivery including maternal age, health geographical region, pre-pregnancy body mass index (BMI), hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), preterm birth (PTB), and multiple gestations was used to compare cumulative incidence in each cohort. Wilcoxon signed-rank test and Fisher exact test for continuous and categorical variables, respectively, were used to compare the characteristics between RPL and non-RPL groups. Cohort I included 4,531 (2.7%) patients in the RPL group and 161,895 (97.3%) individuals in the non-RPL group. Cohort II included 1,069 (3.4%) patients in the RPL group and 30,824 (96.6%) participants in the non-RPL group. RPL patients in both cohorts were older at first birth, had higher pre-pregnancy BMI, higher frequency of GDM, HDP, PTB, and multiple gestations compared to those without RPL. The cumulative second live birth rates were higher in cohort I compared to cohort II; 68.3% vs 58.3%. The adjusted hazard ratios of second live birth for RPL patients were similar in both cohorts 0.86 (95% CI 0.83-0.90) in cohort I and 0.88 (95% CI 0.80- 1.00) in cohort II. In cohort I, the median follow-up time was 5.5 years in the RPL group vs 3.8 in the non-RPL group. Cumulative second live birth rates were 52.3% vs 68.7% (P < .0001), respectively. In cohort II, the median follow-up time was 7.3 years in the RPL group vs 5.3 in the non-RPL group. Cumulative second live birth rates were 44.1% vs 58.7% (P < .0001). Having primary RPL history without any other adverse obstetric outcome is associated with a lower likelihood of second live birth. History of other adverse obstetric outcomes decreased the odds of a second live birth in RPL patients.