1. Corticosteroid binding globulin (CBG) concentrations in maternal plasma have been measured throughout pregnancy in a series of 100 singleton pregnancies in 89 normotensive women. Plasma CBG concentrations were monitored also in 10 women with essential or renovascular hypertension. Plasma albumin, Cortisol and oestriol were measured concurrently.
2. Plasma CBG increased two and a half to three times during pregnancy. In those women who developed hypertension in pregnancy (mean arterial pressure > 107 mmHg), the plasma CBG concentrations were significantly lower than in those who remained normotensive. In women who developed hypertension, the CBG either failed to increase at the same rate as in normal pregnancies or the level fell before the appearance of hypertension. The earlier the onset of hypertension, the greater the decline in CBG. In all subjects, the CBG concentration at 34–36 weeks gestation was directly related to the birthweight of the infant.
3. Plasma Cortisol levels were depressed in hypertension relative to that in the normotensive women. Whilst plasma albumin levels decreased at least 30% in most women during pregnancy, the fall tended to be less in hypertensive women, but there was marked overlap between patient groups. Plasma oestriol concentrations were depressed only in the very severely affected cases.
4. It is suggested the CBG concentration is a further reflection of the metabolic abnormalities associated with hypertension in pregnancy, and that it can be used as a marker to identify and monitor those patients at risk.