The 24-hour pattern of the levels of serum progesterone and immunoreactive human chorionic gonadotropin in normal early pregnancy.

The purpose of this study was to characterize the levels of progesterone and hCG and the variability of those levels over 24 h in early pregnancy. Venous blood sampling was performed every 30 min during the first trimester of a subsequently normal pregnancy in 19 women. The variability in each progesterone and hCG data series was evaluated by three methods: 1) comparing the coefficient of variation (CV) of each individual hormone data set to the respective assay CV, 2) examining each data set for pulses, and 3) relating changes in hormone levels to the ingestion of a meal. The CV for each individual progesterone data set was greater than the assay CV (CVprogesterone 3.7%) in all subjects (range, 5.58–21.90%). The CV for each individual hCG data set was greater than the assay CV for hCG (CVhCG, 4.3%) in 17 of 19 subjects (range, 3.27–10.95%). Mean (±se) progesterone and hCG peak frequencies were 2.4 ± 0.3 and 1.7 ± 0.3/24 h, respectively. When postprandial levels of progesterone were normalized to a percen...