However the DMF label recommends use during pregnancy only if potential benefit justifies the potential risk to the fetus.

An ongoing international registry (NCT01911767) prospectively evaluating pregnancy outcomes in women with MS exposed to DMF since the 1^st day of their last menstrual period before conception or during pregnancy. Data were collected at enrollment, 6–7 months of gestation, 4 weeks after estimated delivery date, and 4, 12, and 52 weeks after birth. Ectopic and molar pregnancies, birth defects, congenital anomalies or infant death occurring at ≤52 weeks of age, and maternal death at ≤12 weeks post-delivery, were reported. Potential birth defects were adjudicated by an external expert. Gestational size was classified based on standardized growth charts: small (<10^th percentile), appropriate (10^th–90^th), or large (>90^th).

As of April 2019, 263 patients were enrolled. Median gestational week at 1^st DMF exposure was 1 (range: 1, 13); median fetal DMF exposure duration was 5 (range: 0.1, 40) weeks. Of the 214 pregnancy outcomes reported to date, 197 (92%) were live births and 17 (8%) were fetal losses. Of infants with known gestational age (n=194), 176 (91%) births were full-term and 18 (9%) premature (<37 weeks). There were 16 spontaneous abortions (1 was an ectopic pregnancy), and 1 fetal death at ≥28 weeks of gestation. No perinatal or maternal deaths were reported. Infants (163 with gestational size data) were classified as small 18 (11%), appropriate 134 (82%), and large 11 (7%). Seven (of 197, 4%) infants had confirmed birth defects.

The pregnancy outcome frequencies from the interim analysis did not exceed those observed in the MS and general populations. No safety signal was observed to date.

Support: Biogen