Women with multiple sclerosis (MS) do not experience more relapses right after giving birth, as previously believed, according to a preliminary study.
The study also revealed that mothers with MS who breastfeed their babies have a lower relapse risk compared with those who do not breastfeed.
The data, “Pregnancy-related Relapses in a Large, Contemporary Multiple Sclerosis Cohort: No Increased Risk in the Postpartum Period,” will be presented at the American Academy of Neurology (AAN)’s 71st Annual Meeting, to be held May 4-10 in Philadelphia, Pennsylvania.
“These results are exciting, as MS is more common among women of childbearing age than in any other group,” Annette Langer-Gould, MD, PhD, the study’s lead author from Kaiser Permanente Southern California, said in a press release. “This shows us that women with MS today can have children, breastfeed, and resume their treatment without experiencing an increased risk of relapses during the postpartum period,” she said.
Data from referral centers had indicated that although it was lower during pregnancy, the risk of MS relapses markedly increased right after giving birth. However, this information was reported more than 20 years ago prior to the availability of disease-modifying treatments (DMTs) and magnetic resonance imaging for early diagnosis. So, researchers conducted a study — supported by the National Multiple Sclerosis Society — to assess whether this higher relapse rate “still held true today,” Langer-Gould said.
A total of 466 pregnancies among 375 women with MS were identified from the Kaiser Permanente Southern and Northern California databases, from 2008 to 2016. The team reviewed the medical records of both mother and baby, and conducted surveys on treatment history, breastfeeding, and relapses.
The data revealed that 38% of patients were not on any MS treatment in the year before becoming pregnant. At the start of pregnancy, 14.6% had clinically isolated syndrome, a neurologic episode lasting 24 hours or more that often precedes MS development.
In total, 8.4% of the women analyzed experienced a relapse during pregnancy, while 26.4% had a relapse in the year after giving birth.
The records also showed that 87% breastfed, 35% breastfed exclusively — meaning the baby received only breast milk for two months or more — and 41.2% resumed taking their DMTs.
The annualized relapse rate (ARR) — the number of confirmed relapses per year — declined from 0.39 before pregnancy to 0.07-0.14 during pregnancy. No rebound in disease activity was found after birth. ARR was slightly decreased in the first three months post-partum (0.27), but returned to pre-pregnancy level by months four to six after birth (0.37).
The findings were unchanged after accounting for factors that could affect ARR, such as disease severity prior to pregnancy.
“The lack of rebound disease activity in the early postpartum period is likely due to a combination of inclusion of women from a population-based setting, those diagnosed after a single relapse, and high rates of exclusive breastfeeding,” the researchers wrote.
Women who breastfed exclusively had a nearly 40% lower likelihood of having a relapse than women who did not breastfeed. No difference in risk of relapses was found between women supplementing breast milk with formula within two months after delivery, and those not breastfeeding at all.
Forty-six of the 167 women who breastfed exclusively resumed their DMTs while breastfeeding. Starting to take modestly effective DMTs did not alter the relapse rate. These DMTs were most commonly interferon-betas — such as EMD Serono’s Rebif, Biogen’s Plegridy and Avonex, Bayer’s Betaseron/Betaferon, and Novartis’ Extavia — and glatiramer acetate (such as Teva’s Copaxone, and Sandoz and Momenta’s Glatopa).
As for limitations in their study, the team mentioned the low proportion of patients treated with Tysabri (natalizumab, by Biogen) or Gilenya (fingolimod, by Novartis) prior to pregnancy. This precluded definitive conclusions related to two medications normally used by patients with greater disease severity. Severe relapses associated with stopping these treatments during pregnancy have been reported.