Withdrawing DMF in early pregnancy does not increase relapse risk in pregnant patients with MS

In a multicentre study, interrupting treatment of multiple sclerosis (MS) with dimethyl fumarate (DMF) in early pregnancy was not associated with a higher relapse risk during pregnancy. Early treatment restart within 1 month after delivery was protective against postpartum relapses. Also, new-borns exposed to DMF during early gestation do not seem to have an increased risk of adverse outcomes.

Prof. Doriana Landi (University of Rome Tor Vergata, Italy) presented the results of a retrospective observational study investigating pregnancy outcomes after exposure to DMF in a cohort of patients with relapsing-remitting MS (RRMS) in 29 Italian MS centres [1]. This study aimed to assess both maternal and foetal safety of exposure to DMF. In the Tor Vergata Hospital, 17% of pregnant patients with MS were on DMF. Data was collected between March 2022 and March 2023.

Prof. Landi's group identified 150 pregnancies in patients who interrupted DMF treatment after conception. Of these, 125 full-term pregnancies were analysed, resulting in 127 new-borns. 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 risk of MS relapse. The annualised relapse rate (ARR) was 0.21 in the year before pregnancy, 0.07 during pregnancy, and 0.22 in the first year after pregnancy (see Figure for full results). Prof. Landi explained that 25 women (20%) had at least 1 relapse postpartum and 17 of these 25 (68%) had the first relapse before they restarted DMF or another form of treatment. Factors associated with a lower relative risk of relapse were restarting therapy postpartum within 1 month and breastfeeding (see Figure).

Figure: Maternal clinical outcomes: ARR [1]



New-borns exposed to early gestation treatment did not seem to have an increased rate of adverse outcomes. Mean foetal DMF exposure was 1.12 months (95% CI 0.00–7.07). The rate of pregnancy loss (12 abortions and 1 stillbirth) was within the expected range for the general population. Congenital anomalies, all minor, were reported in 5 new-borns (3.94%), haematological abnormalities in 2 new-borns (1.57%). All in all, Prof. Landi said that these results were “pretty reassuring”.

1. Landi D, et al. Pregnancy Outcomes After Exposure to Dimethyl Fumarate in an Italian multicentric cohort of women with MS. EAN 2023 Annual Meeting, 1-4 July, Budapest, Hungary.

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Posted on 7 September 20237 September 2023