The following is a summary of “A comprehensive analysis of the association between placental pathology and recurrent preterm birth,” published in the December 2022 issue of Obstetrics and Gynecology by Suresh, et al.

After preterm birth, the placenta is frequently subjected to a histologic investigation. A placental examination can help predict the likelihood of negative pregnancy outcomes even if it cannot alter the fate of the index pregnancy. The relationship between certain histologic lesions and pregnancy outcomes has been investigated in the past, but the findings were inconsistent. For a study, researchers sought to ascertain the separate contributions to recurrent preterm delivery of the main histologic categories of placental disease.

A retrospective cohort analysis of births at a tertiary care facility from January 2009 to March 2018 was conducted. A placental pathology report from the index pregnancy, ≥2 births, and an index birth <37 weeks of gestation was required for inclusion. From the pathology reports for each index placenta, the presence of maternal vascular malperfusion, fetal vascular malperfusion, acute inflammation, and chronic inflammation were extracted and categorized as none, low grade, or high grade. The relationships between each placental histologic type and the risk of recurrent preterm delivery were estimated using a log-binomial model that included all 4 placental pathological histologic categories, index gestational age, race, and maternal age. Moreover, two-way interaction terms between different placental histologic categories were investigated. On the basis of the features of the index preterm birth, 2 stratified analyses were also completed: one by late preterm (gestational age of 34–36 weeks) vs. early–moderate preterm birth (<34 weeks), and one by those who had spontaneous preterm delivery. 

The inclusion criteria were satisfied by 924 pregnant couples in total. Only persistent high-grade inflammation was independently linked to a higher risk of subsequent preterm births (adjusted risk ratio, 1.37; 95% CI, 1.03–1.81). Maternal vascular malperfusion was exclusively linked to recurrent preterm delivery among individuals who had an early preterm birth, according to a stratified analysis by gestational age group (adjusted risk ratio, 1.40; 95% CI, 1.01-1.93). There was no correlation between the histologic kinds of disease and the probability of preterm delivery among patients with spontaneous preterm labor.

Recurrent preterm delivery was linked to high-grade chronic placental inflammation among index preterm pregnancies. Only individuals with an early or moderately preterm index birth (<34 weeks of gestation) were at risk for low-grade maternal vascular malperfusion and subsequent preterm births. The results may help identify a patient’s risk profile and in generating theories on the cause of recurrent preterm delivery.