Human placental lactogen (hPL) model for the normal pregnancy.

This study includes 75 females with normal pregnancies, and presents individual cases of longitudinal series of human placental lactogen (hPL). Samples for hPL levels are taken during the period from gestational week 26 and until labour. A modified Gompertz equation is defined, characterized as growth at a continuously decreasing exponential rate, which finally plateaus in gestational week 36. This modified Gompertz equation adequately fitted individual hPL series. The work describes that a final hPL forecast for the normal pregnancy could be obtained in gestational week 30 using knowledge on maternal height and age, combined with a single hPL sample. The present model was applied in six pathological pregnancies with intrauterine growth retardation, and in all cases measured hPL levels were below the model estimate.