Multiple Sclerosis Increases Risk for Infection During Pregnancy

Pregnant woman at the doctor's office.
Pregnant woman at the doctor’s office.
Investigators examined pregnancy outcomes in patients with multiple sclerosis.

Mothers with multiple sclerosis (MS) are at increased risk for infections during pregnancy and preterm delivery, according to a study published in The American Journal of Epidemiology.

Researchers used 2 large healthcare databases to evaluate the risk associated with pregnancy and delivery for mothers with MS. The Truven Health MarketScan Commercial Claims and Encounters Database provided long-term follow-up, and the Nationwide Inpatient Sample provided discharge samples. Data collection included information such as age, location, household income, and chronic conditions at baseline, throughout pregnancy, or at delivery. Insurance codes were used to track variables associated with pregnancy outcomes, including infections, Cesarean section, preterm delivery, poor fetal growth, preeclampsia, chorioamnionitis, postpartum hemorrhage, stillbirth, and infant malformations.

The Truven population included 1,102,604 pregnancies with 0.13% of mothers having MS, and the Nationwide Inpatient Sample population included 4,186,816 pregnancies with 0.06% of mothers having MS. In both databases, patients with MS were older, from the Northeast, and had chronic conditions such as depression, anxiety disorders, pre-existing hypertension, and thyroid disorders. Infections during pregnancy occurred in 51.7% of the mothers with MS and in 43.4% of the mothers without MS. Mothers with MS had more Cesarean sections and an increased risk for preterm delivery. The risk to the infant for major malformations was 4% in both groups. For mothers with MS, relapse occurred during prepregnancy in 10% of the cohort, in the first trimester for 5% of the cohort, in the second trimester for 4% of the cohort, and in the third trimester for 3% of the cohort. There were no meaningful pregnancy differences found among those mother who relapsed and those who did not.

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Since this was a study relying on insurance codes, classifications for both MS and pregnancy outcomes could be incorrect.

In conclusion, the risk for infection and preterm birth is higher for mothers with MS, although “their risk for other adverse pregnancy outcomes was not meaningfully elevated.”

This study was supported by the Canadian Institutes for Health Research and National Institute of Mental Health. Please refer to reference for a complete list of authors’ disclosures.


MacDonald SC, McElrath TF, Hernándes-Díaz S. Pregnancy outcomes in women with multiple sclerosis. [published online August 28, 2018]. Am J Epidemiol. doi: 10.1093/aje/kwy197