A case of a normal pregnancy and delivery with extremely low placental lactogen hormone (hPL) values in maternal blood is presented. The low hPL-values were due to the fact that the placenta only produced about 1/25 of the normal estimated output, calculated on the basis of the hPL-concentration in the intervillous spaces. The concentrations of progesterone, the placenta-specific beta-glycoprotein (SP1) and total estriol in serum were normal, while prolactin and chorionic gonadotropin (hCG) were considerably elevated. Glucose levels were normal. At the ultrastructural level the actual placenta under study did not differ from a normal term placenta. In spite of the very low concentrations of hPL there was a good milk secretion, and the mother was still breast-feeding her baby 11 months after the delivery. Basal level of prolactin was at this time normal.

Oral glucose tolerance tests (OGTT) were carried out in 9 normal pregnant women and 11 non-obese gestational diabetics in late pregnancy. All samples were analysed for the content of glucose, insulin and placental lactogen hormone (HPL). Furthermore, spontaneous changes in the serum HPL concentration during a 3 h period were studied in 6 normal women in the 2nd half of pregnancy.

Serial maternal serum a,-fetoprotein (AFP) quantitations were carried out in legal induced first and second trimester abortions by both a double antibody radioimmunoassay (RIA) and by a simple radioimmunoelectrophoretical (RIEP) technique. In seven cases of first trimester abortions carried out by suction curettage a marked immediate increase in maternal AFP was found in four cases. No change was dbserved in the remaining three. In six cases of legal second trimester abortions induced by instillation of 20 per cent sodium chloride solution a ma'rked increase in maternal serum AFP was found in all cases. The increased AFP concentration found in induced second trimester abortions took place before death of the fetus and reached a maximum value a few hours after delivery of the fetus. As expected a rapid fall in the serum concentration of HPL and progesterone is seen when suction curettage is used. However, by instillation of a 20 per cent sodium chloride solution only a slight initial decrease is found for both HPL and progesterone.

Summary. A simple rocket‐immunoelectrophoretic method suitable for quantitation of human placental lactogen hormone in sera or plasma samples from pregnant women is described. The samples are used undiluted since the corcentration range is 1–8 mg/l. A close correlation was found between the present method and a commercially available radioimmunoassay. The day‐to‐day reproducibility in terms of relative standard deviation was found to be 4.6%. The mean half life of HPL in 3 patients just after delivery was found to be 16 minutes. Some examples of clinical applications are given in curve form.