A systematic study was carried out on a thousand samples in order to study the distribution of the levels of HPL, SP1 and SP3 in pregnancy. Levels of alpha feto-protein and of alpha antitrypsin as well as of orosomucoid were also studied but only in high-risk pregnancies. When a retrospective study had been carried out after delivery with the object of finding out the value of these levels it was shown that only the levels of SP1 and HLP were useful prognostically. SP1 levels were more reliable apparently as an indicator of feto-placental function. (HLP is the equivalent of HPL human placental lactogen. HP1 is pregnancy specific beta 4-glycoprotein and SP3 is alpha 2-acute phase glycoprotein).