Circulating human pregnancy zone protein and oestriol in twin pregnancies

Abstract
Women with twin pregnancies were matched with those carrying singleton pregnancies (n = 35 for both) for features which are considered to influence pregnancy zone protein (PZP) concentrations. The mean PZP level was significantly lower (P < 0.01) and the mean total estriol level was higher (P < 0.001) in twin than in singleton pregnancies. PZP levels were negatively correlated to estriol levels in twin (r = -0.5756, P < 0.001) and singleton (r = -0.3821, P < 0.01) pregnancies.