71. Altered composition of the gut microbiota in women who develop hypertensive disorders of pregnancy

Abstract

Introduction Metabolites released by the gut microbiota affect host physiology. Hypertension is associated with altered composition of the gut microbiota. In early pregnancy, the abundance of bacteria producing the short-chain fatty acid butyrate, is negatively correlated with blood pressure in the mother. Butyrate may affect blood pressure through affecting GPR41 and 43 signalling. It is unclear if gut microbiota composition is altered in women who develop hypertensive disorders of pregnancy (HDP). Objective To compare the composition of the gut microbiota at 28 weeks gestation between women who do and do not develop HDP later in pregnancy. Methods Gut microbiota composition was assessed by 16S rRNA sequencing in faecal samples obtained from participants in the Study of Probiotics IN gestational diabetes (SPRING) RCT at 28 weeks gestation. In SPRING, women were randomised to a probiotics or placebo intervention from 16 weeks gestation. Gut microbiota composition was assessed using the QIIME and Calypso software suites. The composition was compared between women with future HDP (N = 32) and those who remained normotensive (N = 182). Results Rates of HDP and overall gut microbiota composition were similar between women randomised to probiotics (7.1%, N = 15) and placebo (8.0%, N = 17; P = 0.85) and the treatment groups were therefore pooled. At 28 weeks gestation, the women with future HDP already had significantly higher systolic and diastolic blood pressures than those who remained normotensive. Women with future HDP had higher abundance of Collinsella aerofasciens, Ruminococcus gnavus, Blautia producta and Bifidobacterium longum. They had lower abundance of Faecalibacterium prausnitzii, Coprococcus eutactus and Roseburia faecis, which are all known butyrate producers. Discussion The gut microbiota of women with future HDP has lower abundance of butyrate-producing bacteria at 28 weeks gestation prior to the development of overt hypertension. This may suggest that lower abundance of short-chain fatty acid producers predisposes to the development of HDP.