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

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.

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.

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.

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.