WEST PALM BEACH, FLA. – Women who have no history of a full-term pregnancy show an earlier onset of progressive multiple sclerosis (MS) compared to those who do have pregnancies, and the apparent onset-delaying effect appears to increase with the number of pregnancies, according to new research adding to speculation of the effects of pregnancy in MS.
Dr. Jeffrey A. Cohen
“Our results suggest that a higher number of full-term pregnancies than average is associated with later onset of progressive MS, while having no full-term pregnancies is associated with significantly younger age at progressive MS onset,” first author Burcu Zeydan, MD, an assistant professor of radiology in the Center of MS and Autoimmune Neurology at the Mayo Clinic in Rochester, Minn., said in an interview.
The study was presented at the meeting held by the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS).
The findings, which also link early menopause with faster disease progression, offer important insights into the broader effects of pregnancy on MS, said ACTRIMS president Jeffrey A. Cohen, MD, director of Experimental Therapeutics at the Mellen Center for MS Treatment and Research at the Cleveland Clinic.
“We know pregnancy affects the short term disease activity – relapses tend to quiet down during pregnancy – but what has been somewhat conflicting is whether it affects the long-term prognosis or is just a temporary effect,” he said in an interview.
“So that is the main interest in this study, and it does indicate that pregnancy affects the long-term prognosis and provides some insight into the mechanism by which it might do that.”
While being female is in fact considered the most important risk factor for MS susceptibility, pregnancy has been suggested to have a protective role in disease progression, but more research is needed on the nature of the effect – and its mechanisms.
For the study, Dr. Zeydan and colleagues evaluated data on 202 patients with MS who were part of a Mayo Clinic survey, including 134 women and 68 men.
They found that women who had no full-term pregnancies (n = 32), had an earlier onset of progressive MS (mean age 41.4 ± 12.6 years) compared to women giving birth to 1 or more children (n = 95; 47.1 ± 9.7 years; P = .012).
In addition, the mean age of progressive MS onset also increased with a dose-effect trend according to number of full pregnancies (no children, 41.4 ± 12.6 years; 1-3 children: 46.4 ± 9.2 years; 4 or more children: 52.6 ± 12.9 years; P = .002).
A look at a subgroup of patients with secondary progressive MS also showed an earlier mean age of onset among women who had no full pregnancies (n = 19; 41.5 ± 9.2 years) compared to women with 1 or more full pregnancies (n = 57; 47.3 ± 10.6 years; P = .049).
The later disease onset associated with pregnancy was also seen in relapsing-remitting MS: Mean age of onset was earlier women with no pregnancies (27.5 ± 7.0 years) compared to those with one or more children (33.0 ± 9.4 years; P = .021).
The trends of later onset with more pregnancies was also observed with the mean age of onset of secondary progressive MS (no full pregnancies: onset at 41.5 ± 9.2 years; 1-3 pregnancies: 46.2 ± 9.9 years; 4 or more pregnancies, onset 52.6 ± 12.9 years; P = .010).
And likewise, the later mean age of onset of relapsing-remitting MS was seen with additional pregnancies (no full pregnancies: 27.5 ± 7.0 years; 1-3 pregnancies: 32.4 ± 9.3 years; 4 or more pregnancies: 35.8 ± 9.8 years; P = .012).
“The dose effect was clearly a surprise (having no full-term pregnancies vs. 1-3 vs. 4 or more),” Dr. Zeydan said.
“In addition to the significant difference between having no versus one or more full-term pregnancies, the clear dose-effect consolidates our results related to the association between the number of pregnancies and age at progressive MS onset.”