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Study: Pregnancy increases risk of autoimmune diseases
Last reviewed: 30.06.2025

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A successful pregnancy increases the risk of developing autoimmune diseases such as lupus, rheumatoid arthritis and multiple sclerosis. This is the conclusion reached by a group of specialists led by Keelin O'Donoghue from the Irish National University in Cork. The article about the study was published in the journal PLoS ONE.
O'Donoghue's group conducted a retrospective study of more than a million women born in Denmark between 1962 and 1992. 44.3% of the participants had a child born as a result of a normal birth, 43.3% had never been pregnant, 7.6% of the women had their first child born by caesarean section, and 4.1% had an abortion.
Scientists identified 25,570 cases of autoimmune diseases among all participants. According to the results of the work, the risk of developing such diseases in women who gave birth naturally and with the help of surgeons exceeded the same indicator in the group of Danish women who had not been pregnant by 15 and 30%, respectively. At the same time, the risk of autoimmune diseases among those who had an abortion was 30 percent lower than in the control group.
Previous studies have shown that fetal cells enter the mother's bloodstream early in pregnancy and can be found in bone marrow for decades. Researchers believe that by attacking foreign cells, the mother's immune system begins to react to its own tissues, leading to the development of autoimmune diseases.
O'Donoghue noted that during a Caesarean section, more of the baby's blood enters the woman's body than during a natural birth. This explains the higher risk of autoimmune diseases in Danish women who gave birth by surgery.
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