Multiple sclerosis, disease-modifying drugs and risk for adverse perinatal and pregnancy outcomes: Results from a population-based cohort study.

Background: There is a paucity of information on maternal multiple sclerosis (MS) and risk of adverse pregnancy and perinatal outcomes.

Objective: The aim of this study was to determine the association between MS and risks of adverse pregnancy and perinatal outcomes in women with MS. In women with MS, the influence of exposure to disease-modifying therapy (DMT) was also investigated.

Methods: Population-based retrospective cohort study on singleton births to mothers with MS and matched MS-free mothers from the general population in Sweden between 2006 and 2020. Women with MS were identified through Swedish health care registries, with MS onset before child's birth.

Results: Of 29,568 births included, 3418 births were to 2310 mothers with MS. Compared with MS-free controls, maternal MS was associated with increased risks of elective caesarean sections, instrumental delivery, maternal infection and antepartum haemorrhage/ placental abruption. Compared with offspring of MS-free women, neonates of mothers with MS were at increased risks of medically indicated preterm birth and being born small for gestational age. DMT exposure was not associated with increased risks of malformations.

Conclusions: While maternal MS was associated with a small increased risk of few adverse pregnancy and neonatal outcomes, DMT exposure close to pregnancy was not associated with major adverse outcomes.