PHILADELPHIA – according to a study to be presented at the annual meeting of the American Academy of Neurology.
“We did not observe any rebound disease activity,” said, and her research colleagues in their report.
The findings contrast with those of 20-year-old studies that first identified a lower risk of relapse during pregnancy but signficant rebound disease activity in the early postpartum period. The initial studies were conducted before disease-modifying treatments (DMTs) were available and before neurologists used MRI to help diagnose MS after one attack, noted Dr. Langer-Gould in a.
In the large, contemporary cohort of patients with MS, the annualized relapse rate was 0.39 pre-pregnancy, 0.07-0.14 during pregnancy, 0.27 in the first 3 months postpartum, and 0.37 at 4-6 months postpartum. Exclusive breastfeeding significantly reduced the risk of postpartum relapses by 42% (adjusted hazard ratio = 0.58). Women who supplemented breast milk with formula within 2 months of delivery had the same risk of relapse as women who did not breastfeed, however.
“These results are exciting, as MS is more common among women of childbearing age than in any other group,” said Dr. Langer-Gould, who is regional lead for clinical and translational neuroscience at Kaiser Permanente Southern California in Pasadena, in the statement. “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.”
To describe the risk of postpartum relapses and identify potential risk factors for relapse the investigators analyzed prospectively collected data from 466 pregnancies among 375 women with MS from the complete electronic health record at Kaiser Permanente Southern and Northern California between 2008 and 2016. The researchers also used surveys to collect information about treatment history, breastfeeding, and relapses. They used multivariable models to account for intraclass clustering and disease severity.
In 38% of the pregnancies, the mother had not received treatment in the year before conception. In 14.6%, the mother had a clinically isolated syndrome; in 8.4%, the mother had a relapse during pregnancy.
Resuming modestly effective DMTs such as interferon-betas and glatiramer acetate did not affect relapse risk.
In the postpartum year, 26.4% of mothers relapsed, 87% breastfed, 35% breastfed exclusively, and 41.2% resumed using DMT.
The lack of rebound disease activity in this cohort could be related to the high rate of exclusive breastfeeding, as well as the inclusion of women from a population-based setting and the inclusion of women who had incorrectly been diagnosed with MS after a single relapse. Few patients in this cohort had been treated with natalizumab or fingolimod prior to pregnancy, so the study does not address the potential harms of stopping these drugs or the potential benefits of breastfeeding among patients treated with these drugs.
The study was supported by the National Multiple Sclerosis Society. The researchers had no disclosures.
SOURCE: Langer-Gould A et al. AAN 2019, Abstract S6.007.