MS Relapse Rates Decrease During Pregnancy, Increase Postpartum

October 5, 2018

The majority of relapses were treated in an outpatient setting, and that the rate of outpatient relapses very sharply declined during pregnancy.

Maria K. Houtchens, MD, MMSc

New data has shown that the rate of relapses in women with multiple sclerosis (MS) fluctuates during and after a period of pregnancy, as does the use of disease-modifying therapy (DMT), though most women did not appear to use DMTs during pregnancy.

Ultimately, the findings showed that odds of MS relapse decreased during pregnancy (odds ratio [OR], 0.623; 95% CI, 0.521 to 0.744; P <.0001), then increased during puerperium (OR, 1.710; 95% CI, 1.358 to 2.152; P <.0001), and finally ended at a higher level in the 6 to 9 months following birth (OR, 1.216; 95% CI, 1.052 to 1.406; P = .0081).

Led by Maria K. Houtchens, MD, MMSc, the research team used data from women with MS and a live birth from January 1, 2006, to June 30, 2015, totaling 2,158 patients. Relapses were categorized on a basis of outpatient visits, emergency room visits, and hospitalizations.

“It is estimated that between one-fifth and one-third of women with MS deliver a child after disease onset, making pregnancy in women with MS of significant relevance to patients, their family members, and their health care providers,” Houtchens and colleagues wrote. “More evidence to support decision-making in women with MS of childbearing age is needed in order to improve available clinical support, health care services, and quality of life for this population.”

The findings revealed an adjusted monthly rate of total relapses of 1.47 during the 9 to 12 months prior to pregnancy and dropped to 0.87 during the second trimester. However, rates peaked at 2.56 relapses per month during puerperium, and although they flattened slightly to 1.76 by 9 to 12 months postpartum, they remained elevated compared to pre-pregnancy rates.

The OR between the pregnancy periods and puerperium for outpatient relapses was 4.488 (95% CI, 3.134 to 6.426; P <.0001). Houtchens and colleagues noted that the rates of relapses which required an emergency visit remained relatively stable throughout the study period (P >.05).

“When relapses were stratified into levels of resource utilization intensity, which served as proxies for relapse severities, it was observed that the majority of relapses were treated in an outpatient setting, and that the rate of outpatient relapses very sharply declined during pregnancy,” they wrote.

The odds of a relapse that required hospitalization increased significantly during the third trimester (OR, 1.849; 95% CI, 1.280 to 2.670; P = .0011) as well as during the puerperium period (OR, 2.315; 95% CI, 1.478 to 3.626; P = .0002) in comparison with the pre-pregnancy period. The OR between the pregnancy periods and puerperium for relapses requiring hospitalization was 2.050 (95% CI, 1.284 to 3.272; P = .0026).

Treatment with DMTs was found to be low overall. Between 3 to 12 months pre-pregnancy, roughly 20% of patients were taking a DMT (range, 442 to 445). The rate dropped to a bottom of 1.9% during the second trimester and a peak of 25.5% at 9 to 12 months postpartum. During pregnancy the rate of DMT use declined significantly (OR, 0.171; 95% CI, 0.144 to 0.203; P <.0001). As stated previously, that rate remained low during puerperium (OR, 0.361; 95% CI, 0.312 to 0.418; P <.0001), and increased during the final 3 postpartum quarters (OR, 1.259; 95% CI, 1.156 to 1.371; P <.0001).

The use of DMTs during pregnancy remains controversial and current recommendations advise avoiding them unless the disease risks significantly outweigh the risk of fetal exposure. Houtchens and colleagues acknowledged that their findings were consistent with this, with DMT use being more common in women with a greater number of relapses during the year before pregnancy.

“It was surprising that nearly 20 years after the Pregnancy in Multiple Sclerosis study, a minority of eligible patients with MS are receiving [DMTs] prior to pregnancy,” they noted. “The intent of the study was to provide women with MS who are considering pregnancy or those who are pregnant and their health care professionals with information on other patients’ experiences of care, the burden of disease, and real-world treatment approaches.”

REFERENCE

Houtchens MK, Edwards NC, Phillips AL. Relapses and disease-modifying drug treatment in pregnancy and live birth in US women with MS. Neurology. 2018;00:e1-e9. doi: 10.1212/WNL.0000000000006382.