Body composition and energy metabolism in normotensive and hypertensive pregnancy

Objective To determine whether the insulin resistance syndrome and altered body composition are features of hypertensive pregnancy.

Design Women were recruited in the third trimester of pregnancy from the antenatal clinic, day assessment unit, and maternity ward of St George Hospital, Sydney.

Population Women with pre-eclampsia (n=12), gestational hypertension (n=12), essential hypertension in pregnancy (n=11), and normotensive pregnancy (n=10).

Methods Energy metabolism was assessed by indirect calorimetry to measure basal metabolic rate and diet-induced thermogenesis. Body composition was measured as lean body mass, total body water and fat mass by bio-electrical impedance. Blood was collected for measurement of glucose, insulin and lipid profiles. Insulin resistance was indirectly assessed by the insulin and glucose concentrations and diet-induced thermogenesis.

Results Women with essential hypertension and gestational hypertension were heavier than women with normotensive pregnancies both pre-pregnancy and in the third trimester, whereas women with pre-eclampsia were similar to those with normotensive pregnancy. Women with essential hypertension were otherwise similar to normotensive pregnancy but women with gestational hypertension had a reduced diet-induced thermogenesis and almost double insulin levels. Women with pre-eclampsia had a similar body composition and insulin levels but reduced basal metabolic rate, diet-induced thermogenesis and glucose levels compared with normotensive pregnancy.

Conclusions Women who develop gestational hypertension, but not pre-eclampsia, are more likely to be overweight. Women with essential hypertension are similar to women with normotensive pregnancy throughout pregnancy. Both gestational hypertension and pre-eclampsia appear to be associated with some degree of insulin resistance, greater than that occurring in normal pregnancy.