Pregnancy outcomes in multiple sclerosis following subcutaneous interferon beta-1a therapy

Background: Women with multiple sclerosis (MS) are advised to discontinue interferon-beta therapy before trying to conceive. Unplanned pregnancies occur and risks related to exposure remain unclear. Methods: To determine pregnancy outcomes following interferon-beta therapy, we examined pregnancies from a global drug safety database containing individual case safety reports received in the post-marketing setting and safety data from clinical trials of subcutaneous interferon beta-1a in MS. Results: One thousand and twenty-two cases of exposure to subcutaneous interferon beta-1a during pregnancy were retrieved; 679 had a documented outcome. In cases for which exposure duration was available (n = 231), mean time of foetal exposure to subcutaneous interferon beta-1a before treatment discontinuation was 28 days; most pregnancies (199/231; 86.1%) were exposed for <= 45 days. To avoid bias, only outcomes for prospective data (n = 425) in pregnancies exposed to interferon beta-1a in utero were analysed further. Of these, 324 (76.2%) resulted in normal live births and four (0.9%) in live births with congenital anomalies (3 [0.7%] were 'major'). Four (0.9%) pregnancies resulted in stillbirths (1 [0.2%] with foetal defects). There were 5 (1.2%) ectopic pregnancies, 49 (11.5%) spontaneous abortions and 39 (9.2%) elective terminations. Most pregnancies exposed to subcutaneous interferon beta-1a in utero were associated with normal live births. The rates of spontaneous abortion and major congenital anomalies in live births were in line with those observed in the general population. Conclusions: These data should be taken into account when considering options for women with MS who become pregnant or who are planning pregnancy while on treatment with subcutaneous interferon beta-1a.