Fewer Women With MS Choosing to Stop DMT Use While Pregnant

The use of disease-modifying therapies (DMTs) by pregnant women with multiple sclerosis (MS) significantly increased over the last decade or so, and fewer of them are stopping treatment before giving birth, a single-center study in Italy reported.

While most patients (95.1%) discontinued a DMT while pregnant between 2005 and 2012, more than half (53%) of those who became pregnant between 2013 and 2020 continued using their therapy, without greater risks to the mother or child.

Continued use of DMTs in recent years has led to significant reductions in relapse rates before and after a pregnancy, although not during pregnancy, when relapse rates are generally low.

“Probably due to increasing knowledge and availability of [DMTs] approved for use during pregnancy and breastfeeding we detected a higher tendency to not discontinue treatment before conception and to maintain [DMT] even during pregnancy from 2014 to present,” the researchers wrote.

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The study, “Pregnancy planning and management for women with multiple sclerosis: what has changed over the last 15 years? An Italian single-center experience,” was published in the journal Multiple Sclerosis and Related Disorders.

MS often affects women of childbearing age, particularly between the ages of 20 and 40. As such, MS specialists need to consider fertility and pregnancy issues when taking into account therapeutic choices.

Relapse rates are well known to decline during pregnancy, raising again to pre-pregnancy levels about one year after delivery. With limited safety data regarding the use of DMTs during pregnancy, most women prefer to discontinue their treatment while pregnant and breastfeeding, which risks a faster accrual of disability.

In recent years, data from clinical trials and real-world studies have aided in understanding the safety profile of DMTs for MS, with several now considered safe for use during pregnancy, particularly in the earlier trimesters, and while breastfeeding.

How that knowledge has changed the use of these treatments, however, is still being addressed.

Researchers at the University of Catania examined data covering women with relapsing-remitting MS (RRMS), being followed at their MS center, who became pregnant between January 2005 and December 2020.

Overall, 190 women with MS were included in the analysis — 102 (53.7 %) became pregnant between 2005 and 2012, and 88 (46.3%) between 2013 and 2020. Most of these patients had one pregnancy (72.6%), with the others having either two (21.6%) or three pregnancies (5.8%).

Disease onset occurred significantly later in life among women who became pregnant starting in 2013 — their  mean age was 25.3, compared with a mean of 23.6 for the earlier group. Age at first pregnancy also was significantly higher in the 2013–2020 group, 33.1 vs. 30.9.

Of 253 recorded pregnancies across both periods, 233 (88.1 %) were in patients using a DMT. Most were being treated with interferon-based medications (54.2% of all pregnancies). Other common therapies included Tysabri (natalizumab), glatiramer acetate (sold as Copaxone, among other brands), Tecfidera (dimethyl fumarate). Other DMTs accounted for less than 3% of use.

Treatment was discontinued before conception in 49 of these 223 pregnancies (22%), and during pregnancy in 115 cases (51.6%). For 59 pregnancies (26.5%), the women remained on their disease-modifying treatment across all study years.

53% of pregnant patients continued with DMT in 2013-20, 4.9% in 2005-12

Discontinuation patterns significantly differed between the two periods. Most notably, 53% of patients in the second period continued with a DMT during pregnancy, while 4.9% chose to do so in the first period.

Relapse rates fell during pregnancy for both groups — from 0.3 relapses each year in the year before pregnancy to 0.1. These rates rose again to 0.3 relapses per year in the year after pregnancy.

Both before and after pregnancy, however, annual relapse rates were significantly lower in women who became pregnant in 2013 or later than in patients with pregnancies between 2005 and 2012. Women in the first group also experienced greater disability accumulation, moving from 1.3 points in the Expanded Disability Status Scale (EDSS) before pregnancy to 1.4 points during pregnancy, and 1.7 points in the year after giving birth.

A similar disability accrual was not observed in the second patient group.

Among the 223 pregnancies, 180 resulted in full-term deliveries, 30 were pre-term, and two post-term. A total of 42 cases of fetal death (29 miscarriages, 12 voluntary abortions, and one intrauterine death) were registered. No associations were found between pregnancy outcomes and the two periods.

“Our study showed a trend reversal in the use of [DMT] during pregnancy in the last 15 years, with a clear tendency to not discontinue [DMT] during pregnancy unless clearly contraindicated, especially when high-efficacy [DMT] was administered before conception,” the researchers wrote.

“This choice was not associated to increased safety concerns for mothers and offspring and to higher percentages of miscarriages,” they added.