Pausing DMF treatment in early pregnancy doesn’t raise relapse risk, while restarting treatment within a month after delivery reduces postpartum relapses.

Interrupting treatment with dimethyl fumarate (DMF) in early pregnancy is not associated with a higher relapse risk during pregnancy, according to a study presented at EAN 2023. Furthermore, early treatment restart within 1 month after delivery may protect against postpartum relapses, and newborns exposed to DMF during early gestation do not seem to have an increased risk of adverse outcomes.

These were the main conclusions from a retrospective observational study presented by Doriana Landi, MD, PhD. The study assessed pregnancy outcomes after exposure to DMF in a cohort of patients with relapsing-remitting multiple sclerosis (RRMS) in 29 Italian MS centers. This study aimed to assess maternal and fetal safety of exposure to DMF. In the Tor Vergata Hospital, 17% of pregnant patients with MS were on DMF. Data were collected between March 2022 and March 2023.

Dr. Landi and colleagues identified 150 pregnancies in women who interrupted DMF treatment after conception. Of these, 125 full-term pregnancies were analysed, resulting in 127 newborns. The mean age at conception was 33 years, the median Expanded Disability Status Scale (EDSS) before conception was 1.5 (range, 0-4.5), the median duration of DMF treatment was 19.23 months (3.00-72.89 months); 90 women restarted DMF after delivery, with a median interval of 1.48 months (0.03-11.01).

The main maternal clinical outcome was that DMF interruption early during pregnancy was not associated with an increased relapse rate. The annualised relapse rate (ARR) in the year before pregnancy was 0.21 (95% CI, 0.14-0.30), ARR during pregnancy was 0.07 (95% CI, 0.03-0.14; P=0.003), and in the first year after pregnancy 0.22 (95% CI, 0.15-0.32). Dr. Landi explained that 25 women (20%) had at least one relapse postpartum, 17 of whom (68%) had the first relapse before they restarted DMF or another treatment. Factors associated with a lower relative risk (RR) of relapse were higher age at conception (RR, 0.87; 95% CI, 0.76-0.99; P=0.035), restarting therapy postpartum within 1 month (RR, 0.16; 95% CI, 0.03-0.57; P=0.012), and breastfeeding (RR, 0.22; 95% CI, 0.03-0.89; P=0.069).

Newborns exposed to early gestation did not seem to have an increased rate of adverse outcomes. Mean fetal DMF exposure was 1.12 months (95% CI, 0.00-7.07). The rate of pregnancy loss (12 abortions and one stillbirth) was within the expected range for the general population. Congenital anomalies, all minor, were reported in 3.94% of newborns (hematological abnormalities in two newborns [1.57%]). All in all, Dr. Landi said the results were “pretty reassuring.”

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