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How the immune system acts during pregnancy

A nurse cares for a premature baby (M. Spencer Green / AP)

A woman's immune system balances two jobs during pregnancy: preventing itself from attacking the fetus as it would foreign tissue and keeping the mother safe from infection herself. Disruptions to this balance can cause a host of complications for the pregnancy, namely delivery at 34 weeks — six weeks sooner than what is considered normal and healthy. In the U.S., 10–12% of babies are born before full term.

Stanford researchers have detailed what this balance (referred to as the "immune clock") should look like in a pregnancy in which the baby is delivered at term, per a new study.

Why it matters: "Once you understand what is normal…you can understand what is abnormal," Brice Gaudilliere, one of the researchers, told Axios. With the model "immune clock" on hand, doctors may be able to predict whether a woman will deliver preterm by observing if that clock is ticking too slow or too fast.