No abstract

This study is the first report of antenatal levels of relaxin measured by homologous radioimmunoassay in peripheral serum from patients who subsequently had a preterm delivery. Serial blood samples were collected antenatally from a group of subjects known to be at increased risk of preterm labour because of a past history of shortened pregnancy. Serum relaxin was measured using a n homologous radioimmunoassay based o n a synthetic bioactive analogoue of the native hormone. In women whose pregnancies ended preterm most measurements were within the range of values previously established in normal antenatal patients although some measurements early in pregnancy were above t h e normal range. These findings suggest that low serum levels of relaxin are not causatively related to the onset of labour before term.It has bcen reported that the application of an extract of the human corpus luteum of pregnancy to human myometrium caused a decrease in the amplitude of spontaneous contractions in vitro. The extract was shown to contain immunoreactive and bioaetive relaxin (Szlachter et a/.edge the co-operation of the staff and patients of the Queen Victoria Medical Ccntrc.