Pregnancy Can Delay MS Onset by 3 Years, Study Says

A recent global study found that pregnancy can delay the onset of multiple sclerosis (MS) by more than 3 years.

The study looked at 2557 women who were patients in Australia and the Czech Republic with clinically isolated syndrome, a subset of MS.

MS is most often diagnosed in women of childbearing years. Pregnancy could reduce the abnormal over-activity of the immune system that causes MS, potentially long term, said the authors, writing in JAMA Neurology.

Researchers collected data on gravida, defined as any pregnancy, whether live or spontaneous miscarriage or termination, and parity, defined as childbirth after gestational age of more than 10 weeks, including livebirth and stillbirth.

Of these women, 1188 (46%) had at least 1 pregnancy and 1100 (43%) had at least 1 childbirth. Investigators found that later-onset CIS was more common in women with previous pregnancies and childbirths compared to those who had never been pregnant (HR, 0.68; 95% CI, 0.62–0.75; P <.001), with a median delay of 3.3 years (95% CI, 2.5–4.1).

A similar delay in MS onset was also observed in women who had delivered at term, with onset delayed, on average, by 3.4 years.

Of the 2557 women, 71 (3%) had their first MS symptom during pregnancy.

Having 1 (HR, 0.70; 95% CI 0.61–0.79), 2 (HR, 0.67; 95% CI, 0.60–0.76), or 3 or more pregnancies (HR, 0.66; 95% CI, 0.58–0.75) delayed the onset of CIS compared with no pregnancies (P <.001).

A higher number of pregnancies and childbirths was not associated with later CIS onset.

The researchers noted that although it is known that pregnancy is linked to reduced MS activity, the effect of pregnancy before MS diagnosis is unclear.

Investigators noted that further studies are needed to help explain the mechanisms behind the associations between pregnancy and onset of MS.

Reference

Nguyen A, Vodehnalova K, Klinicik T, et al. Association of pregnancy with the onset of clinically isolated syndrome. JAMA Neurol. Published online September 14, 2020. doi: 10.1001/jamaneurol.2020.3324.