Accurate assessment of early gestational age in normal and diabetic women by serum human placental lactogen concentration.

Serum human placental lactogen (hPL) and human chorionic gonadotropin (hCG) were assayed and fetal crown-rump length (CRL) was determined by sonar in three groups of pregnant women--35 with uncomplicated pregnancies, 13 with insulin-dependent diabetes mellitus, and 21 who represented a general pregnancy population. Each patient had a regular cycle and recorded last menstrual period, ovulated spontaneously, and was delivered of a single live baby. Serum hPL concentrations within the range 0.01-0.80 microU/ml in patients in the first group gave estimates of gestation with an SD of 6.3 days which was the same as the SD derived from CRL measurements. When the hPL regression equation was applied to the diabetic mothers the difference between the gestational age estimated from hPL and that estimated from LMP had a mean value of - 0.9 days with an SD of 6.2 days; this difference was not significantly different from zero. The third group of patients had a mean difference between hPL and LMP derived gestational age of 0.7 days (+/- 6.7 SD). Serum hPL offers a method of estimating gestation sufficiently precise to be used as a practical alternative to sonar measurements of CRL.