Patterns of Serum Immunoreactive Human Placental Lactogen (IR-HPL) and Chorionic Gonadotropin (IR-HCG) in Diabetic Pregnancy

Serum levels of immunoreactive human placental lactogen (IR-HPL) and chorionic gonadotropin (IR-HCG) were evaluated in eighty-four diabetic patients classified according to White. All patients in this group were treated with estrogen/progesterone therapy throughout pregnancy and were compared with a small group of twenty-seven diabetic patients not receiving hormonal therapy. In 164 normal pregnancies, serum IR-HPL is detected first at about six weeks and rises steadily to plateau levels of 6.2 ± 1.4 μg./ml. at thirty-five to thirty-seven weeks. In eighty-four diabetic pregnancies, the pattern of steady rise in IR-HPL levels simulates normal but the mean values are significantly greater than normal with peak values of 10.3 ± 4.7 /μg./ml. at thirty-five to thirty-seven weeks. Serum IR-HCG is first measured in normal pregnancy at about five to seven weeks by this assay, rises rapidly to peak levels of 163 ± 60 IU./ml. at eight to ten weeks and then falls to a nadir of 12.0 ± 2.0 IU./ml. at seventeen to nineteen weeks. Thereafter, there is a gradual secondary rise to a lesser mean peak value of 63 ± 19 IU./ml. at thirty-five to thirty-nine weeks. In diabetic pregnancy, the pattern of serum IR-HCG is similar to normal but with striking quantitative differences. The mean values in the second and third trimesters are significantly higher than normal with extreme variations among different pregnant individuals. The clinical implications of these abnormalities are not clear but suggest that the excessive secretion of HCG may mollify the diabetic imposition of early pregnancy whereas HPL contributes to the exaggerated glucose intolerance in late pregnancy.