Childbirth delivery mode and the risk of multiple sclerosis: a prospective population-based study.

BACKGROUND: Caesarean section (CS) may affect the risk of developing multiple sclerosis (MS) in the offspring, possibly through changes in gut microbiota composition, but findings from previous studies are inconsistent. We investigated whether birth by CS was associated with the risk of adult-onset MS. METHODS: We conducted a prospective population-based cohort study, including all individuals born in Norway between 1967 and 2003, using the Medical Birth Registry of Norway linked with the Norwegian Multiple Sclerosis Registry and Biobank. The follow-up was until 2021. We used multivariable Cox models to estimate HRs for MS risk with 95% CIs. RESULTS: Among 2 046 637 individuals in the cohort, 4954 MS cases were identified. Being born by CS was associated with a modest increase in MS risk (HR=1.18, 95% CI 1.05 to 1.32). In the sibling-matched analysis, we found no association between CS and MS risk. We found an interaction between CS and gestational age (p=0.03): CS was associated with an increased risk of MS in individuals born preterm (HR=1.62, 95% CI 1.18 to 2.24), whereas there was no association in individuals born at term (HR=1.13, 95% CI 0.99 to 1.27). In a subgroup analysis of individuals born in 1988 and onwards, emergency CS was related to an elevated MS risk (HR=1.40, 95% CI 1.07 to 1.83), whereas planned CS was not (HR: 1.10, 95% CI 0.77 to 1.58). CONCLUSIONS: CS was associated with a modestly higher risk of developing MS. However, the stronger associations seen in subgroups who likely experienced a more complicated pregnancy/delivery may point to confounding underlying these associations.

Abuse and revictimization in adulthood in multiple sclerosis: a cross-sectional study during pregnancy.

BACKGROUND: Knowledge concerning exposure to abuse in adulthood and in pregnancy in people with multiple sclerosis (MS) is sparse. OBJECTIVE: To determine the occurrence of adult abuse and abuse in relation to pregnancy in women with MS and their risk of revictimization (repeated abuse as adults after childhood abuse). METHODS: This cross-sectional study comprised pregnant women from the Norwegian Mother, Father and Child Cohort study. Information on abuse was acquired through self-completed questionnaires. We used logistic regression to estimate adjusted odds ratios (aORs) with 95% confidence intervals (CIs). RESULTS: We identified 106 women with MS at enrollment through linkage with national health registries. The reference group consisted of 77,278 women without MS. Twenty-seven women (26%) with MS reported any adult abuse compared to 15,491 women (20%) without MS, aOR 1.33 (0.85-2.09). Twenty-two (21%) women with MS reported systematic emotional abuse compared to 13% without MS, aOR 1.75 (1.08-2.83). Ten women (10%) with MS reported sexual abuse, compared to 6% without MS, aOR 1.72 (0.89-3.33). More women with MS reported rape as an adult, aOR 2.37 (1.02-5.49). Women with MS had higher risk of revictimization as adults, after childhood abuse, aOR 2.23 (1.22-4.10). The risk of abuse during pregnancy or 6 months preceding pregnancy was similar between the groups. CONCLUSIONS: Women with MS had increased occurrence of systematic emotional abuse, rape, and revictimization as adults, compared to women without MS.