Ultrasound measures of abdominal subcutaneous adipose tissue in pregnancy

Abstract

Obesity in pregnancy is associated with an increased risk of adverse pregnancy and neonatal outcomes. Central adipose tissue (AT) has been found to be more predictive of metabolic disease than body mass index (BMI). Ultrasound (US) can be used to measure AT in the non-pregnant population and is highly correlated with other imaging methods. The aim of this work was to assess subcutaneous AT (SAT) measures throughout pregnancy and post-partum using ultrasound to determine the value of ultrasound measures in pregnancy. The measurement of SAT in the first and second trimester of pregnancy were assessed in 1500 women. A subset (575) of the women had other anthropometric measures performed in early pregnancy. US measures were used to predict adverse pregnancy outcomes and comparison was made with anthropometric measures. This study demonstrated that US measured abdominal SAT could predict adverse pregnancy outcomes and correlated well with other anthropometric measures in early pregnancy. It also demonstrated a change in SAT measures at two-time points in early pregnancy, was different for the BMI categories. A study of 214 women, was then performed to measure and assess abdominal SAT thickness, at four-time points during pregnancy and post-partum. The two layers of SAT were measured. Strain elastography assessed AT density and a food frequency questionnaire assessed maternal diet. There were differences in abdominal SAT distribution within the SAT layers across BMI categories and AT mobilisation during pregnancy and post-partum. A difference in the density of the two layers of AT was shown. Density of AT is associated with AT fibrosis, a marker of AT health and metabolic dysfunction. Superficial SAT (SSAT) became less dense post-partum associated with an increase in the SAT thickness. Diet assessment demonstrated no difference in macronutrient balance and energy intake across the BMI categories. A relationship between macronutrient balance was found in SAT, SSAT and deep SAT layer. When dietary fat decreased there was an associated decrease in density of SSAT suggesting a decrease in AT fibrosis. There is a potential of US to provide essential information about the metabolic health of pregnancy which is beneficial in determining the cause of heterogeneity in metabolic disease due to the differences in AT distribution by BMI.