A Description of the Imaging Innovations for Placental Assessment in Response to Environmental Pollution Study

Abstract

Objective: The aim of PARENTs was to determine whether imaging of the placenta by novel multi-parametric MRI techniques in early pregnancy could help predict adverse pregnancy outcomes due to ischemic placental disease (IPD). Additionally, we sought to determine maternal characteristics and environmental risk factors that contribute to IPD and secondary adverse pregnancy outcomes. Study Design: Potential subjects in their first trimester of pregnancy, who agreed to MRI imaging of the placenta and measures of assessment of environmental pollution, were recruited into PARENTs, a prospective population-based cohort study. Participants were seen at three study visits during pregnancy and again at their delivery from 2015 to 2019. We collected data from interviews, chart abstractions, and imaging. Maternal biospecimens (serum, plasma, and urine) at antepartum study visits and delivery specimens (placenta, cord, and maternal blood) were collected, processed, and stored. The primary outcome was a composite of IPD, which included any of the following: placental abruption, hypertensive disease of pregnancy, fetal growth restriction (FGR), or a newborn of small-for-gestational-age (SGA). Results: In this pilot cohort, of the 190 subjects who completed pregnancy to viable delivery, 50 (26%) developed IPD. Among demographic characteristics, having a history of prior IPD in multiparous women was associated with the development of IPD. In the multiple novel perfusion measurements taken of the in vivo placenta using MRI, decreased high placental blood flow (hPBF; ml/100g/min) in early pregnancy (between 14-16 weeks) was found to be significantly associated with the later development of IPD. Conclusion: Successful recruitment of the PARENTs prospective cohort demonstrated the feasibility and acceptability of the use of MRI in human pregnancy to study the placenta in vivo and at the same time collect environmental exposure data. Analysis is ongoing and we hope these methods will assist researchers in the design of prospective imaging studies of pregnancy.

Association of ischemic placental disease in a Southern California Birth Cohort and PM2.5 chemical species and oxidative potential markers

“…The PARENTs study enrolled a birth cohort of pregnant women who sought prenatal care and planned to deliver at UCLA hospitals between 2016 and 2019. Details regarding the cohort are summarized elsewhere [25]. Briefly, subjects were screened for eligibility early in the first trimester and subsequently followed prospectively until birth.…”

“…We defined the main outcome, IPD, as the noted presence of one or more of the following complications: placental abruption, hypertensive disease of pregnancy (preeclampsia or gestational hypertension), a newborn considered small-for-gestational age, or fetal growth restriction. Fetal growth restriction was defined as fetuses with an estimated fetal weight or abdominal circumference that was less than the 10th percentile for gestational age [25]. These four diseases, while symptomatically different, are all related to a placental ischemia induced by excessive oxidative stress and are grouped under the composite outcome IPD [11].…”

“…While the study's small sample size limits the ability to draw specific comparisons between the minimal and adjusted model, the results nonetheless suggest that the effect sizes and direction observed in the crude and minimally adjusted models are not due to confounding due to variables including parity, maternal BMI, maternal smoking, gestational diabetes, maternal education, or household income. As stated elsewhere [25], we designed the PARENTs cohort to study placenta-related adverse outcomes in pregnancy, i.e. a high-risk population of pregnant women with a high prevalence of IPD.…”

“…We employ conventional exposure metrics, namely PM 2.5 , black carbon, and novel set of exposure measures, including tracers of brake and tire wear and markers of oxidative potential. We relied on a well-documented birth cohort [25] with detailed clinical follow-up throughout pregnancy to assess associations of IPD with different measures of ambient TRAP.…”