The type of bacteria that colonize¹ the placenta（胎盘） during pregnancy² could be associated with preterm birth and other developmental problems in newborns according to research published in the current issue of the online journal mBio®. "The fetal（胎儿的） inflammatory response appears to contribute to the onset³ of preterm labor⁴, fetal injury and complications, underlying⁵ lifetime health challenges facing these children," say the researchers from Harvard Medical School, Brigham and Women's Hospital and Children's Hospital of Boston. "Our data suggest that placental colonization⁶ by specific groups of organisms can increase or decrease the risk of a systemic inflammatory condition."

Preterm birth occurs in nearly a half million pregnancies⁷ in the United States alone. Despite improved care, preterm and especially extremely low-gestational-age newborns continue to be at a considerably⁸ higher risk of morbidity⁹（发病率） , mortality and developmental problems. Much of this risk is attributable to imbalanced inflammatory responses of the fetus¹⁰ and newborn.

The systemic fetal inflammatory response to intrauterine（子宫内的） exposures, especially intrauterine infections, is regarded as an important contributor to the onset and often lifelong consequences of preterm labor, fetal injury and early organ damage. Approximately half of all placentas delivered before the second trimester（三个月） and 41% of those delivered by Caesarean section harbor microorganisms detectable¹¹ by culture techniques.

In order to better understand what role, these microorganisms could play in the extremely preterm inflammatory response the researchers analyzed¹² protein biomarkers in dry blood spots obtained from 527 newborns delivered by Caesarean section and cultured and identified the bacteria from their respective placentas.

Placentas colonized¹³ primarily by microorganisms commonly associated with the condition know as bacterial¹⁴ vaginosis (BV细菌性阴道病) were found to be associated with elevated levels of proinflammatory protein in newborns. In contrast, colonization by Lactobacillus species of bacteria (often found in decreased concentrations during BV) were associated with lower levels of proinflammatory proteins.

"Our study supports the concept that the placental colonization with vaginal microorganisms can induce a systemic inflammatory response in the fetus and newborn and that the dominating molecular¹⁵ feature of this response can be dependent on the type of bacteria," says Andrew Onderdonk of Harvard Medical School and Brigham and Women's Hospital, one of the authors of the study. "Our data suggest that the targeting of placental colonization by specific drugs or probiotics（益生菌） during early pregnancy may hold promise for preventing not only preterm birth but also the devastating¹⁶ and far-reaching inflammatory consequences in premature¹⁷ newborns."