Maternal Underweight and Obesity Are Associated with Placental Pathologies in Human Pregnancy

Abstract

Introduction: Maternal underweight and obesity are prevalent conditions, associated with chronic, low-grade inflammation, poor fetal development, and long-term adverse outcomes for the child. The placenta senses and adapts to the pregnancy environment in an effort to support optimal fetal development. However, the mechanisms driving these adaptations, and the resulting placental phenotypes, are poorly understood. We hypothesised that maternal underweight and obesity would be associated with increased prevalence of placental pathologies in term and preterm pregnancies.Methods: Data from 12,154 pregnancies were obtained from the Collaborative Perinatal Project, a prospective cohort study conducted from 1959 to 1974. Macro and microscopic placental pathologies were analysed across maternal prepregnancy body mass index (BMI) to assess differences in the presence of pathologies among underweight, overweight, and obese BMI groups compared to normal weight reference BMI at term and preterm. Placental pathologies were also assessed across fetal sex.Results: Pregnancies complicated by obesity had placentae with increased fetal inflammation at preterm, and increased inflammation of maternal gestational tissues at term. In term pregnancies, increasing maternal BMI associated with increased maternal vascular malperfusion (MVM), odds of an appropriately mature placenta for gestational age, and placental weight, and decreased placental efficiency. Male placentae, independent of maternal BMI, had increased inflammation, MVM, and placental efficiency than female placentae, particularly at term. Discussion: Maternal underweight and obesity are not inert conditions for the placenta, and the histomorphological changes driven by suboptimal maternal BMI may serve as indicators of adversities experienced in utero and potential predictors of future health trajectories.

Maternal Exposure to Environmental Air Pollution and Premature Rupture of Membranes: Evidence from Southern China

“…Secondly, being underweight may reflect the nutritional status of pregnant women, and malnutrition could weaken the immune system, thereby increasing sensitivity to environmental pollutants[ 33 ]. Additionally, the BMI of underweight individuals could intensify lung deposition and retention of particles [ 34 ]. Further research is warranted to delve deeper into the mechanisms underlying these associations, ultimately paving the way for informed strategies to mitigate the risks posed by prenatal air pollution exposure on maternal and fetal health.…”

The influence of early environment and micronutrient availability on developmental epigenetic programming: lessons from the placenta

“…Further, the placenta has a large impact on fetal development and placenta-related adverse pregnancy outcomes can influence later life disease. Placental function can be influenced by many environmental exposures, such as maternal smoking and obesity ( Reijnders et al, 2019 ; Scott et al, 2022 ). Increased physical activity before and during early pregnancy can reduce the incidence of preeclampsia ( Aune et al, 2014 ).…”

Placental pathology and fetal growth outcomes in pregnancies complicated by maternal obesity

“…(15)(16)(17)(18) Variable histopathological changes have also been reported in placentas of women with obesity, including both delayed and accelerated villous maturation, maternal vascular lesions, and chronic villitis. (15)(16)(17)(18)(19) Some of these studies cite small sample sizes, while others have a study design that is limited to term gestation, which could explain the mixed results.…”

“…Interestingly, fetal sex is also known to affect adaptive changes in the placenta in response to altered maternal/uterine environment, including obesity, and has also been associated, not just with adverse pregnancy/neonatal outcomes, but also with speci c placental pathologies. (11,(19)(20)(21) As part of a large institutional effort to identify underlying causes of pregnancy complications, we previously conducted a study to evaluate placental pathology in the setting of maternal obesity, focusing on patients delivering at or near term. (22) This study found maternal obesity to be associated with large placental disc weight for gestational age and decreased placental e ciency, histopathologic lesions of chronic in ammation (speci cally chronic villitis [CV]) and fetal vascular malperfusion (FVM), and intrauterine fetal stress as manifested by normoblastemia, independent of diabetes and hypertension.…”