Prevalence of pregnancy outcomes after exposure to interferon beta before or during pregnancy stratified by maternal characteristics: A register-based cohort study in Finland and Sweden

Objective: To describe the prevalence of serious adverse pregnancy outcomes (SAPO) among pregnant women with multiple sclerosis (MS) exposed to only interferon-beta (IFNβ) and those unexposed to any MS disease modifying drugs (MSDMD), with stratification by maternal characteristics. Background: A recent cohort study in women with MS reported no increase in the prevalence of adverse pregnancy outcomes after exposure to IFNβ before or during pregnancy. However, differing prevalence by maternal characteristics is unknown. Design/Methods: This cohort study extracted register data from Finland (1996–2014) and Sweden (2005–2014) on pregnant women with MS 1) dispensed only IFNβ within 6 months before the last menstrual period (LMP) or during pregnancy (IFNβ-exposed, n=718 pregnancies) and 2) without dispensed MSDMD (unexposed, n=1397 pregnancies). The prevalence (%) of SAPO (consisting of elective terminations due to foetal anomaly, major congenital anomalies in live birth, and stillbirth) with 95% confidence intervals (CI) was analysed with stratification by maternal characteristics at LMP: time since MS diagnosis, duration of MS treatment, maternal age, and having chronic diseases. Results: The prevalence of SAPO appeared similar among the IFNβ-exposed vs. unexposed when MS was diagnosed ≤2 years (0.9%, 95%CI 0.1–3.2% vs. 3.0%, 1.6–5.2%) or 3–5 years (2.4%, 0.9–5.1% vs 6.0%, 4.0–8.6%) before LMP, and was comparable for >5 years (3.3%, 1.4–6.4% vs 3.0%, 1.7–4.8%). When stratified by duration of MS treatment, the prevalence among the IFNβ-exposed vs. unexposed with ≤2-year treatment was 1.3% (0.4–3.4%) vs 4.6% (2.9–6.9%), 3–5-year treatment 1.7% (0.5–4.4%) vs 4.9% (2.9–7.7%), and >5-year treatment 4.3% (1.9–8.3%) vs 2.7% (1.2–5.0%). The prevalence was similar among the IFNβ-exposed vs unexposed in strata by maternal age (≤20, 21–25, 26–30, 31–35, 36–40, >40 years) and having chronic diseases (yes/no). Conclusions: In this population-based observational study, the descriptive prevalence of SAPO appeared similar with IFNβ-exposure before or during pregnancy, when pregnant women with MS were stratified by maternal characteristics. Disclosure: Dr. Korjagina has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with MK is an employee of StatFinn and EPID Research which performs commissioned pharmacoepidemiological studies for several pharmaceutical companies. Dr. Hakkarainen has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with StatFinn and EPID Research.Dr. Burkill has nothing to disclose. Dr. Geissbuhler has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Novartis Pharma AG. Dr. Sabido Espin has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Meritxell Sabido is an employee of Merck KGaA, Darmstadt, Germany.. Dr. Kumar has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen. Dr. Suzart-Woischnik has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Bayer AG, Pharmaceuticals, Mullerstrasse 178, 13353 Berlin, Germany. Dr. Suzart-Woischnik holds stock and/or stock options in Bayer AG, Pharmaceuticals (employee stocks) which sponsored research in which Dr. Suzart-Woischnik was involved as an investigator. Dr. Suzart-Woischnik holds stock and/or stock options in Bayer AG, Pharmaceuticals (employee stocks). Dr. Klement has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with RK is an employee of StatFinn and EPID Research which performs commissioned pharmacoepidemiological studies for several pharmaceutical companies. Dr. Hillert has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Merck, Biogen, Novartis, Sandoz, Celgene, and Sanofi. Dr. Hillert has received research support from Biogen, Novartis, Merck, and Roche.Dr. Verkkoniemi-Ahola has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Yes, consulting, scientific advisory board or speaking. Biogen, Merck, Sanofi, Roche, Orion.. Dr. Verkkoniemi-Ahola has received research support from Sanofi (Lemtrada post-marketing safety follow-up). Dr. Bahmanyar has nothing to disclose. Dr. Montgomery has received research support from Roche, Novartis, AstraZeneca, IQVIA. Dr. Korhonen has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with PK is an employee of StatFinn and EPID Research which performs commissioned pharmacoepidemiological studies for several pharmaceutical companies.. Dr. Group has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Merck, Biogen, Novartis, and Bayer. Dr. group has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employees of StatFinn and EPID Research which performs commissioned pharmacoepidemiological studies for several pharmaceutical companies.