Impact of interferon beta exposure on birth outcome and child development - Results from the post-authorisation safety study PRIMA.

Background: Interferon beta therapies are well-established disease-modifying treatments for patients with relapsing multiple sclerosis (MS). Based on clinical evidence from two large cohort studies, both, the EMA and FDA updated the labels of the interferon beta class in terms of pregnancy and breastfeeding in 2019 and 2020, respectively. To complement pregnancy label updates with patient-reported real-world data, this study examined German pregnancy and outcome reports including available data on child development from women with MS treated with peginterferon beta-1a or intramuscular (IM) interferon beta-1a.

Methods: The post-authorisation safety study PRIMA included adult women diagnosed with relapsing-remitting MS or clinically isolated syndrome, who were treated with peginterferon beta-1a or IM interferon beta-1a before or during pregnancy and registered in the marketing authorisation holder's MS Service center patient support program. In the prospective part of the study, conducted from April to October 2021, data on developmental milestones of the newborns were collected via telephone interview from mothers reporting live births.

Results: In total, 426 women were enrolled, reporting 542 pregnancies that resulted in 466 live births. A total of 162 women completed the questionnaire for 192 live births (53.1% male). Newborns had Apgar scores indicative of healthy infants. Weight, length and head circumference at birth and physical growth curves up to 48 months lay within the expected range of the German general population. Most newborn screenings and examinations during check-ups were inconspicuous over the study period of 48 months. Out of 158 breastfed infants, 112 (70.9%) were breastfed exclusively until month 5.

Conclusion: Study results confirmed former reports indicating that exposure to interferon beta therapies during pregnancy or lactation had no adverse effects on intrauterine growth and child development over the study period, which covered the first 4 years of life. These real-world data obtained within the scope of a patient support program for peginterferon beta-1a or IM interferon beta-1a corroborate German and Scandinavian registry data and support the label update of all interferon beta therapies.

Registration: NCT04655222, EUPAS38347.