Associations of maternal blood pressure-raising polygenic risk scores with fetal weight

Adverse pregnancy outcomes, familial predisposition, and cardiovascular risk: a Swedish nationwide study

BACKGROUND AND AIMS

Adverse pregnancy outcomes (APOs) are recognized as significant female-specific risk factors for cardiovascular disease (CVD). A potential shared familial susceptibility between APOs and CVD has been proposed, but not thoroughly explored. This study employs a quasi-experimental family comparison design to investigate shared familial predisposition between APOs and CVD, by assessing risk of CVD in APO-exposed women and their APO-free sisters.

METHODS

Nationwide population-based cohort study encompassing primiparous women, without prior CVD, with registered singleton births in the Swedish Medical Birth Register between 1992 and 2019, grouped into: women with ≥1 APO (165 628), APO-free sisters (60 769), and unrelated APO-free comparator women (992 108). All study participants were followed longitudinally, through linkage with national health registers, from delivery until 2021, for primary endpoint major adverse cardiac events, and its individual components: ischaemic heart disease, heart failure, and cerebrovascular events.

RESULTS

Over a median follow-up of 14 years, APO-exposed women exhibited increased rates of CVDs compared with APO-free comparators. Adverse pregnancy outcome-free sisters exhibited elevated adjusted hazard ratios (aHRs) of major adverse cardiac event {aHR 1.39 [95% confidence interval (CI) 1.13-1.71]}, heart failure [aHR 1.65 (95% CI 1.14-2.39)], and cerebrovascular events [aHR 1.37 (1.04-1.72)] compared with the APO-free comparators, while no significant increase in ischaemic heart disease was observed. Within-family analysis revealed lower CVD rates in APO-free sisters compared with their APO-exposed counterparts, except for no significant difference in cerebrovascular events.

CONCLUSIONS

Sisters of women with APOs face a moderately increased risk of CVD, suggesting a genetic and/or environmental influence on the association between APOs and CVDs. These findings underscore the need for evaluating the effectiveness of targeted preventive measures in women with APOs and their sisters.

Alterations in the Gut Microbiome and Metabolisms in Pregnancies with Fetal Growth Restriction

Fetuses diagnosed with fetal growth restriction (FGR) are at an elevated risk of stillbirth and adulthood morbidity. Gut dysbiosis has emerged as one of the impacts of placental insufficiency, which is the main cause of FGR. This study aimed to characterize the relationships among the intestinal microbiome, metabolites, and FGR. Characterization was conducted on the gut microbiome, fecal metabolome, and human phenotypes in a cohort of 35 patients with FGR and 35 normal pregnancies (NP). The serum metabolome was analyzed in 19 patients with FGR and 31 normal pregnant women. Multidimensional data was integrated to reveal the links between data sets. A fecal microbiota transplantation mouse model was used to determine the effects of the intestinal microbiome on fetal growth and placental phenotypes. The diversity and composition of the gut microbiota were altered in patients with FGR. A group of microbial species altered in FGR closely correlated with fetal measurements and maternal clinical variables. Fecal and serum metabolism profiles were distinct in FGR patients compared to those in the NP group. Altered metabolites were identified and associated with clinical phenotypes. Integrated multi-omics analysis revealed the interactions among gut microbiota, metabolites, and clinical measurements. Microbiota from FGR gravida transplanted to mice progestationally induced FGR and placental dysfunction, including impaired spiral artery remodeling and insufficient trophoblast cell invasion. Taken together, the integration of microbiome and metabolite profiles from the human cohort indicates that patients with FGR endure gut dysbiosis and metabolic disorders, which contribute to disease pathogenesis. IMPORTANCE Downstream of the primary cause of fetal growth restriction are placental insufficiency and fetal malnutrition. Gut microbiota and metabolites appear to play an important role in the progression of gestation, while dysbiosis induces maternal and fetal complications. Our study elaborates the significant differences in microbiota profiles and metabolome characteristics between women with FGR and normal pregnancies. This is the first attempt so far that reveals the mechanistic links in multi-omics in FGR, providing a novel insight into host-microbe interaction in placenta-derived diseases.

Placenta mediates the effect of maternal hypertension polygenic score on offspring birth weight: a study of birth cohort with fetal growth velocity data

BACKGROUND

Low birth weight (LBW) and fetal growth restriction are associated with the development of cardio-metabolic diseases later in life. A recent Mendelian randomization study concluded that the susceptibility of LBW infants to develop hypertension during adulthood is due to the inheritance of hypertension genes from the mother and not to an unfavorable intrauterine environment. Therein, a negative linear association has been assumed between genetically estimated maternal blood pressure (BP) and birth weight, while the observed relationship between maternal BP and birth weight is substantially different from that assumption. As many hypertension genes are likely involved in vasculature development and function, we hypothesized that BP-increasing genetic variants could affect birth weight by reducing the growth of the placenta, a highly vascular organ, without overtly elevating the maternal BP.

METHODS

Using a birth cohort in the Japanese population possessing time-series fetal growth velocity data as a target and a GWAS summary statistics of BioBank Japan as a base data, we performed polygenic score (PGS) analyses for systolic BP (SBP), diastolic BP, mean arterial pressure, and pulse pressure. A causal mediation analysis was performed to assess the meditation effect of placental weight on birth weight reduced by maternal BP-increasing PGS. Maternal genetic risk score constituted of only "vasculature-related" BP single nucleotide polymorphisms (SNPs) was constructed to examine the involvement of vascular genes in the mediation effect of placental weight. We identified gestational week in which maternal SBP-increasing PGS significantly decreased fetal growth velocity.

RESULTS

We observed that maternal SBP-increasing PGS was negatively associated with offspring birth weight. A causal mediation analysis revealed that a large proportion of the total maternal PGS effect on birth weight was mediated by placental weight. The placental mediation effect was remarkable when genetic risk score was constituted of "vasculature-related" BP SNPs. The inverse association between maternal SBP PGS and fetal growth velocity only became apparent in late gestation.

CONCLUSIONS

Our study suggests that maternal hypertension genes are strongly associated with placental growth and that fetal growth inhibition is induced through the intrauterine environment established by the placenta.