Human placental lactogen (HPL) is a hormone produced by the placenta with a role in the regulation of fetoplacental growth. In this paper, the results of HPL determination in the third trimester of pregnancy are presented with the aim of testing the sensitivity of this biochemical marker for detecting placental dysfunction, fetal vitality and risk of bad outcome. The tests were performed on 370 women with high-risk pregnancy, between the 20th and 36th week of pregnancy. HPL was determined by an ELISA method using Bioserv Diagnostics tests and the results were read by a STAT-FAX 303+ reader. When compared to normal pregnancy, a significant decrease in the level of HPL biomarker was identified in preeclampsia (p<0.01), whereas in diabetes the serum level of HPL was significantly higher (p<0.01). A significant positive correlation between the level of HPL during pregnancy and the weight of a newborn child, its head circumference and Apgar score was obtained. The results of the research indicate that the maternal concentration of the HPL biomarker is directly connected to the vitality of placental tissue, so that HPL in the third trimester of pregnancy can be used as an indicator of placental insufficiency and fetal vitality.