The effects of exercise during pregnancy on placental composition : A systematic review and meta-analysis

Introduction Morphological changes to the placenta occur as the demands of the foetus increase throughout gestation. Physical activity during pregnancy is known to benefit both the mother and infant, however the impact of antenatal exercise training on placental development is less known. The aim of this systematic review and meta-analysis was to investigate the effects of exercise training during pregnancy on measures of placental composition. Methods Six electronic databases were searched from inception to June 2021 for studies comparing regular antenatal exercise with either usual maternal care or no exercise for its effect on measures of placental morphological composition. Meta-analyses were performed for placental weight and the placental weight to birthweight (PWBW) ratio. Results Seven randomised controlled trials and two cohort studies were included in the systematic review and meta-analysis (n = 9). There was no significant difference in placental weight (mean difference (MD) = -9.07g, p = 0.42) or the PWBW ratio (MD = 0.00, p = 0.32) between exercise and control groups. Parenchymal tissue volume was higher, represented by an increase in villous tissue, and non-parenchymal volume was lower in women who exercised regularly compared to those that were not exercising during pregnancy. Discussion Exercise training during pregnancy may not alter placental weight or the PWBW ratio. However, findings from this review indicate that antenatal exercise training can promote advantageous morphological changes to placental tissues

Prenatal Alcohol Exposure is Associated with Sex Specific Alterations to the Placenta and Reduced Cerebroplacental Ratio

Introduction: Prenatal alcohol exposure (PAE) increases the risk of adverse pregnancy outcomes including miscarriage, low birthweight, and neurodevelopmental abnormalities, which may be mediated in part, by poor placental development. PAE is associated with alterations to placental vasculature, blood flow, and gene expression, hypothesised to stem from altered DNA methylation (DNAm). Choline and folate are dietary nutrients that serve as methyl donors for DNAm, however their availability may be compromised by alcohol consumption. This study investigated the impact of PAE on maternal and placental methyl donors, placental growth and the cerebroplacental ratio (CPR), an indicator of brain sparing due to placental insufficiency.Methods: Data and samples were collected from women from the Queensland Family Cohort and classified into abstinent/control (n=109) or PAE (n=302). PAE was subdivided by exposure prior to conception only (PC) or continuing during pregnancy (PCP). Maternal folic acid supplementation and dietary intake of folate and choline were calculated. For a subset of the cohort with Doppler ultrasound data (n=179), measurements of fetal and placental blood flow were used to calculate the CPR. Plasma folate was measured using the Cobas clinical analyser. Plasma choline and placental methyl donors were measured by mass spectrometry. Placental gene expression was quantified by qPCR. Data were analysed separately by fetal sex.Results: PAE was reported by 73% of women; 42% PC and 31% PCP. Women in the PCP group consumed alcohol more frequently prior to conception than those in the PC group. Overall, 67% of women took a folic acid supplement prior to conception and 93% in trimester 1. These proportions were lower in the PCP, compared with the control group (PConclusion: PAE is associated with sex-specific alterations in the placenta, which may be an underlying mechanism for increased susceptibility of male fetuses to adverse outcomes.<br/