Women with multiple sclerosis (MS) are in most cases diagnosed and treated at childbearing age. Some studies with limited sample size suggested that MS and interferon-beta (IFNβ) exposure might affect birth weight and head circumference. Prevalence of these two measures at birth was determined in IFNβ-exposed and unexposed pregnant women with MS from health registers in Finland and Sweden.
Health register data from Finland (1996-2014) and Sweden (2005-2014) were used to study women with MS: 1)dispensed only IFNβ within 6-months prior to date of last menstrual period or during pregnancy (IFNβ-exposed) and 2)without any dispensed MS disease modifying drugs (unexposed). Prevalence (95% confidence interval [CI]) of the following birth outcomes was described for IFNβ-exposed and unexposed women: low birth weight for live births (<2500g), low head circumference for infants with full-term live birth (≥37 gestational weeks) and small or large for gestational age (SGA and LGA respectively). For SGA, LGA, and head circumference, national gestational age and sex-specific national references were used. No adjustments for potential confounding factors were performed.
Among 666 IFNβ-exposed and 1330 unexposed live births, the prevalence of birth outcomes was similar between IFNβ-exposed vs unexposed. Prevalence of low birth weight (95%CI) was 3.9%(2.6-5.7) among IFNβ-exposed and 4.8%(3.7-6.1) among unexposed live births. Among 619 IFNβ-exposed and 1219 unexposed full-term live births, prevalence of low head circumference (95%CI) was 1.9%(1.0-3.4) vs 1.1%(0.6-1.8) respectively. Comparing the IFNβ-exposed vs unexposed, SGA (95%CI) was 2.1%(1.2-3.5) vs 2.0%(1.3-2.9), and LGA (95%CI) was 0.8%(0.2-1.7) vs 0.8%(0.4-1.5).
Data from Finnish and Swedish health registers showed no evidence that IFNβ exposure before and during pregnancy affected infant birth weight and head circumference.
© 2019 Published by Elsevier Inc.