Sepsis in pregnancy doubles risk of birth complications, UCSF study finds

A pregnant woman recovers from a severe infection, takes antibiotics, gets better, and goes home. Her doctors tell her the crisis has passed. But new research from UC San Francisco suggests the story doesn't end there. Even after sepsis—a life-threatening condition triggered by the body's overwhelming response to infection—has been treated and cleared, the damage to pregnancy can persist, reshaping the months ahead and the birth itself.

The UCSF study, published in September 2021, examined 14,565 patients who delivered at the medical center between 2012 and 2018. Among them, 59 had been hospitalized during pregnancy with sepsis, recovered, and were discharged before delivery. The researchers compared their outcomes to the 14,506 who never experienced sepsis. The finding was stark: pregnancies complicated by sepsis carried twice the risk of placental dysfunction—the organ that nourishes the fetus—compared to uncomplicated pregnancies. Beyond that, the data showed increased odds of cesarean delivery, postpartum hemorrhage, and preterm birth.

Dr. Stephanie Gaw, an assistant professor of obstetrics, gynecology, and reproductive sciences at UCSF and the study's senior author, emphasized that these complications emerged not during the acute infection itself but afterward, even among women who had fully recovered. "If pregnant women were admitted for severe infection, even after they're discharged and they recover from that infection, there was an increased risk of complications related to pregnancy that are associated with core placental dysfunction," Gaw said. The finding was novel because prior research had only examined sepsis cases where delivery occurred during the same hospital admission. This was the first study to track what happened to mothers who got sick, recovered, and continued their pregnancies at home.

The timing of infection mattered enormously. Among 26 patients infected before 24 weeks of gestation, the consequences were most severe: 46 percent developed placental dysfunction, 31 percent developed hypertensive disease of pregnancy, and 23 percent gave birth to babies who were small for gestational age. Across the full sepsis group, the mean gestational age at infection was 24.6 weeks. The most common infections were urinary tract infections, accounting for 41 percent of cases, and pulmonary infections at 37 percent.

Sepsis itself ranks as the second leading cause of maternal death in the United States, according to the CDC. It arises when the body's response to infection becomes so severe that it triggers widespread inflammation, potentially leading to organ failure. The condition is rare in pregnancy but carries outsized consequences. Patients in the sepsis group tended to be younger—averaging 30.6 years at delivery compared to 33.1 years overall—and more likely to have pregestational diabetes and higher body mass index scores. Even after researchers adjusted for these and other risk factors, the doubled risk of perinatal complications remained.

Gaw suggested a practical change to prenatal care: adding an extra ultrasound during the third trimester to monitor fetal growth in pregnancies affected by sepsis. Currently, such monitoring is not routine. She also noted that the study, conducted with pre-pandemic data, carries implications for any acute infection during pregnancy, including COVID-19. "Even after you've recovered from COVID, or any other infection, there may be downstream consequences that we should pay attention to," Gaw said. She recommended that women who experience septic infections during pregnancy receive heightened surveillance for the remainder of their pregnancies.

The research points toward a gap in current practice. Most pregnant women who develop sepsis are treated with antibiotics and recover, then continue their pregnancies without knowing that the infection may have altered the placenta in ways that increase risk. Gaw, who also studies malaria in pregnant women globally, hopes the findings will spark further investigation into how the maternal immune response to infection reshapes pregnancy and whether interventions—whether pharmaceutical or procedural—might prevent the long-term placental changes that appear to drive these complications. The question now is whether enhanced monitoring and targeted care can mitigate the risks that linger long after the infection itself has been conquered.