Pregnancy outcomes after early fetal exposure to injectable first‐line treatments, dimethyl fumarate, or natalizumab in Danish women with multiple sclerosis

BACKGROUND AND PURPOSE: Data on pregnancy outcomes following fetal exposure to disease‐modifying drugs (DMDs) in women with multiple sclerosis (MS) are sparse although growing. METHODS: Data from the Danish Multiple Sclerosis Registry were linked with nationwide registries enabling an investigation of adverse pregnancy outcomes in newborns of women with MS following fetal exposure to injectable first‐line treatments, dimethyl fumarate, glatiramer acetate, or natalizumab. Logistic regression models accounting for clustered data were used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for individual and composite adverse outcomes after adjusting for relevant covariates. RESULTS: A total of 1009 DMD‐exposed pregnancies were compared with 1073 DMD‐unexposed pregnancies as well as 91,112 pregnancies from the general population. No association of an increased risk of any perinatal outcome was found when comparing newborns with fetal exposure with the general population, including preterm birth (OR = 1.19, 95% CI = 0.86–1.64), small for gestational age (OR = 1.38, 95% CI = 0.92–2.07), spontaneous abortion (OR = 1.04, 95% CI = 0.84–1.27), congenital malformation (OR = 0.99, 95% CI = 0.68–1.45), low Apgar score (OR = 0.62, 95% CI = 0.23–1.65), stillbirth (OR = 1.05, 95% CI = 0.33–3.31), placenta complication (OR = 0.53, 95% CI = 0.22–1.27), and any adverse event (OR = 1.10, 95% CI = 0.93–1.30). Similar results were found when comparing DMD‐exposed pregnancies with DMD‐unexposed pregnancies. CONCLUSIONS: We found no increased association of adverse pregnancy outcomes in newborns with fetal exposure to DMDs when compared with either DMD‐unexposed pregnancies or the general population.