Autoantibodies May Be Linked to Higher Preterm Birth Risk in Some Women - Video

Could hidden antibodies in a pregnant woman's blood be responsible for triggering premature labour? A new study suggests that certain immune antibodies may contribute to early labour, potentially opening new avenues for predicting and preventing preterm births.

Published in Nature Immunology, the study conducted by researchers at the University of California, San Francisco (UCSF), identified antibodies that appeared earlier and at higher levels in women who subsequently delivered before 37 weeks of pregnancy compared with those who delivered at term.

Preterm birth affects approximately one in ten pregnancies and remains the leading cause of newborn deaths worldwide. Despite its significant health burden, identifying pregnancies at greatest risk has remained a major challenge.

To investigate the role of the immune system, researchers initially collected blood samples from women undergoing fertility treatment and monitored immune changes during pregnancy. Using an advanced antibody profiling technique, they identified antibodies associated with pregnancy.

The team then examined blood samples from more than 2,000 pregnant women across eight cohorts. They found that women who delivered prematurely experienced broader antibody changes earlier in pregnancy.

One antibody was particularly significant because it targeted interleukin-1 receptor antagonist (IL-1RA), a protein that normally helps control inflammation. By interfering with IL-1RA, these antibodies may allow increased activity of IL-1β, an inflammatory molecule associated with uterine contractions.

Experiments in pregnant mice showed that introducing these antibodies increased inflammatory activity and caused placental damage. Further examination of human placental tissue revealed that IL-1RA was concentrated near blood vessel junctions involved in transferring oxygen and nutrients between mother and fetus.

However, researchers cautioned that these antibodies were detected in only a proportion of premature deliveries, indicating that preterm birth has multiple causes. Further studies are needed to establish their predictive value and determine whether targeting this inflammatory pathway can safely prevent early labour.

REFERENCE: Elze Rackaityte, et al.; Evidence for Maternal Autoantibodies in the Pathogenesis of Preterm Birth; Nature Immunology; DOI: 10.1038/s41590-026-02689-y