Comparative study of amniotic fluid and maternal blood serum human placental lactogen in normal and prolonged pregnancies.

The levels of human placental lactogen (hPL) were measured in maternal blood and amniotic fluid in normal and prolonged pregnancies. Statistical analysis of the hPL levels showed that values rose in both blood and amniotic fluid, reaching maximum levels between Weeks 34 and 36 (6.70 microgram per milliliter in blood serum, 0.85 microgram per milliliter in amniotic fluid). Thereafter, there was a decline, a significant fall occuring between Weeks 40 and 42 and in the prolonged pregnancy group (43 weeks and more) (t = 6.9 and p less than 0.001 in serum levels; t = 3.9 and p less than 0.001 in amniotic fluid levels). There was also a very close correlation (r = 021; p less than 0.005) between maternal blood and amniotic fluid hPL levels in normal pregnancies before labor.