Placental protein measurements in complicated pregnancies. III. Premature labour.

Maternal serum levels of pregnancy-associated plasma protein. A (PAPP-A), human placental lactogen (hPL) and schwangerschafts-protein 1 (SP1) were measured serially during second and third trimester in 753 women with normal pregnancy when they were recruited to the study. In 24 women spontaneous premature labour occurred before 37 completed weeks and these women had significantly lower mean levels of serum SP1 at 29-31 weeks and at 33-34 weeks gestations but similar mean levels of serum PAPP-A and hPL at all gestations compared with corresponding values in normal pregnancy. The predictive value of an abnormal SP1 result was 5.2% at 29-31 weeks and 10.3% at 33-34 weeks. Furthermore, trends of levels of the three placental proteins in individual patients were similar to those seen in normal pregnancy, and the trends were unrelated to the occurrence of other complications and the time of onset of labour. This study suggests that measurements of the three placental proteins are unlikely to be of any value in the prediction of spontaneous premature labour.