Longitudinal maternal bioimpedance analysis in pregnancies complicated by hypertensive disorders and/or foetal growth restriction

Objective. To study across-pregnancy maternal body com­position by bioimpedance analysis (BIA) in pregnancies com­plicated by hypertensive disorders (HDP) and foetal growth restriction (FGR).
Materials and Methods. Singleton pregnancies, enrolled at the combined first trimester screening test, underwent ma­ternal BIA at each trimester of pregnancy. According to the pre-existing or pregnancy-related occurred complications, women were finally classified distinguishing pregnancies complicated by HDP, isolated FGR (i-FGR), HDP combined with FGR (HDP-FGR) and uneventful pregnancies (controls). A longitudinal Bayesian multivariate mixed-effects model was performed.
Results. In a cohort of 519 patients, 24 cases of chronic hy­pertension (CH), 19 HDP with appropriate-for-gestational-age foetus (HDP-AGA), 3 HDP-FGR, 12 i-FGR and 40 controls, randomly sampled from the entire uncomplicated pregnancy cohort, were analyzed. Pre-pregnancy body mass index (BMI) was significantly higher in both HDP-AGA and CH than con­trols. Total body water (TBW), lean body mass (LBM) and vis­ceral fat (VF) showed the same trend in all groups, with an average increase from first to second trimester [+1.84 (95%CI 1.13-2.53); +2.55 (95%CI 1.61-3.50); +0.71 (95%CI 0.06-1.36), respectively], and from first to third trimester [+3.26 (95%CI 2.57-3.97); +4.48 (95%CI 3.56-5.43); +1.27 (95%CI 0.62-1.92), respectively]. No statistically significant differences of TBW, LBM and VF were found among groups, once the bioimped­ance parameters were corrected for pre-pregnancy BMI and gestational age at evaluation.
Conclusions. Maternal bioimpedance parameters show a pro­gressive increase across pregnancy in both uncomplicated and pathological pregnancies. Moreover, HDP-AGA and CH are characterized by higher pre-pregnancy BMI, TBW, LBM and VF, a proxy of metabolic syndrome.