Pregnancy Does Not Change Long-term Course of MS, New Data Suggest

Pregnancy does not lead to long-term changes in the disease course of multiple sclerosis (MS), new research suggests.

This work, which emphasizes the importance of careful data analysis, supports studies disputing previous beliefs that pregnancy worsened or lessened the long-term disease course of MS.

The findings were presented by Mar Tintore, MD, PhD, in a plenary lecture titled “Multiple Sclerosis” (number 0452), at the XXIV World Congress of Neurology (WCN 2019), in Dubai, United Arab Emirates (Oct. 27–31).

Tintore is the clinical chief of neurology in the Neurology–Neuroimmunology Department at the Multiple Sclerosis Centre of Catalonia at the Hospital Vall d’Hebron, in Barcelona, Spain.

Since MS occurs more frequently among women of childbearing age, the potential impact of pregnancy in the course of the disease, and vice-versa (including the effects of MS treatments), has been the focus of numerous studies.

While until the 1980s it was thought that pregnancy worsened the clinical course of the disease, several subsequent studies suggested that pregnancy and breastfeeding slowed MS progression.

“To advertise that pregnancy has a very important impact and will positively modify your long-term prognosis is something we must be cautious about because studies show it is not true,” Tintore said in a press release.

She emphasized that this “may cause confusion” among patients, who may believe pregnancy “can replace treatment,” and among providers who may think it could “treat the disease.”

Tintore’s work highlighted that how researchers analyze data can lead to misleading results on the impact of pregnancy in long-term MS disease course.

“Comparing women who had any pregnancy during their disease with women who had not experienced pregnancy during their disease, what you see is that women with pregnancy are better off than those who had never been pregnant,” said Tintore.

“This is not exactly the case when you consider other factors, which makes it likely that pregnancy doesn’t change the trajectory of the disease,” she said.

Other factors that may influence MS progression include the patient’s age, gender, brain lesions at diagnosis, treatment status (on or off) and duration.

These findings supported the increasing number of studies showing that pregnancy does not affect MS clinical course long-term. However, it does change the rate of MS relapses in the short term.

Relapse rate in women with MS decreases during pregnancy — especially in the third trimester — and increases during the first trimester after birth, before normalizing to pre-pregnancy levels.

A previous study also has shown that pregnancy in MS does not seem to be associated with obstetric complications in the mothers or the babies, supporting its non-damaging effect.

However, there is still some uncertainty regarding the best treatment approach, whether or when to stop and resume therapy before pregnancy and after delivery, the relapse rates during and after pregnancy associated with each therapy, and the safety of new therapies.

Increasing efforts are being made to develop consensus guidelines for the management and treatment of women with MS who are pregnant or planning a pregnancy. These guidelines are expected to highlight which treatments are considered safe and appropriate for these women.

Tintore also emphasized that if a woman stops MS treatment while trying to get pregnant, the disease can become “very active,” and that these women “should plan and organize their pregnancy with their doctor to approach the chapter of life thoughtfully, and with the mother’s health top-of-mind.”