Pregnancy and the risk of autoimmune disease

Abstract

Autoimmune diseases (AID) predominantly affect women of reproductive age. While basic molecular studies have implicated persisting fetal cells in the mother in some AID, supportive epidemiological evidence is limited. We investigated the effect of vaginal delivery, caesarean section (CS) and induced abortion on the risk of subsequent maternal AID. Using the Danish Civil Registration System (CRS) we identified women who were born between 1960 and1992. We performed data linkage between the CRS other Danish national registers to identify women who had a pregnancy and those who developed AID. Women were categorised into 4 groups; nulligravida (control group), women who had 1st child by vaginal delivery, whose 1st delivery was by CS and who had abortions. Log-linear Poisson regression with person-years was used for data analysis adjusting for several potential confounders. There were 1,035,639 women aged .14 years and 25,570 developed AID: 43.4% nulligravida, 44.3% had their first pregnancy delivered vaginally, 7.6% CS and 4.1% abortions. The risk of AID was significantly higher in the 1st year after vaginal delivery (RR = 1.1[1.0, 1.2]) and CS (RR = 1.3[1.1, 1.5]) but significantly lower in the 1st year following abortion (RR = 0.7[0.6, 0.9]). These results suggest an association between pregnancy and the risk of subsequent maternal AID. Increased risks of AID after CS may be explained by amplified fetal cell traffic at delivery, while decreased risks after abortion may be due to the transfer of more primitive fetal stem cells. The increased risk of AID in the first year after delivery may also be related to greater testing during pregnancy.

Abortion may be associated with elevated risk of future hypothyroidism

“…[ 5 ] Fetal microchimerism may persist in the postpartum period for decades after the last pregnancy or abortion. [ 7 ] High OR (23.5; P < 0.001) for past abortion in the cases aged 42.2 ± 9.8 years, in our study, shows that the risk for hypothyroidism persists for a lifetime after an abortion.…”

“…[ 6 ] Some investigators, however, believe that microchimeric cells are the innocent bystanders and are not responsible for hypothyroidism in females. [ 7 ] We conducted a case–control study to investigate the odds of “abortion in the past” in the newly diagnosed hypothyroid females compared to their age-matched euthyroid controls.…”

Fetal microchimerism by mode of delivery: a prospective cohort study

“…(14) Because FMc is associated with certain AIDs,(15) the authors of this study speculated that a greater amount of fetomaternal interface disruption may occur during CD compared to VD, allowing for greater cellular transfer. (16)…”

“…14 Because FMc is associated with certain AID, 15 the authors of this study speculated that a greater amount of fetomaternal interface disruption may occur during CD compared with VD, allowing for greater cellular transfer. 16 Because obstetric factors, including mode of delivery, may impact FMc transfer to the mother with potential long-term implications, we sought to evaluate FMc transfer at VD versus CD in women with uncomplicated deliveries.…”

Differences in maternal gene expression in Cesarean section delivery compared with vaginal delivery

“…This led to 81 genes used for clustering samples across the three delivery modes. www.nature.com/scientificreports/ transient, may lead to may lead to an inflammatory and immune cascade and play a role in the reported immune and inflammatory adverse outcomes associated with CS delivery for both mothers and offspring [1][2][3][6][7][8][9][10][11][12][13][14][15][16] ; this warrants further exploration. Other differentially expressed pathways between delivery modes involve the inflammatory and immune pathways (neutrophil degranulation, interferon signaling).…”