N. Kadar et al., A PROSPECTIVE, RANDOMIZED STUDY OF THE CHORIONIC GONADOTROPIN-TIME RELATIONSHIP IN EARLY GESTATION - CLINICAL IMPLICATIONS, Fertility and sterility, 60(3), 1993, pp. 409-412
Objective: To investigate the hCG-time relationship in early pregnancy
. Design: Prospective, randomized study. Setting: Pregnant human volun
teers in a university-based clinical research environment. Patients: N
ormal pregnant women with viable singleton pregnancies, conceived spon
taneously or after ovulation induction. Interventions: Vaginal ultraso
und was performed, and blood samples were obtained for hormone paramet
ers between 20 and 30 days after conception. The timing of the tests w
as determined by random assignment using sealed envelopes. Main Outcom
e Measure: Serum hCG. Results: The log hCG-time relationship was linea
r, both during the first 20 days and between 20 and 30 days after conc
eption. The inclusion of a quadratic term in either regression was not
statistically significant. The slopes of the two regression lines wer
e also not statistically different. Conclusion: For practical purposes
, the hCG-time relationship in early pregnancy can be treated as log-l
inear, but short sampling intervals should be used if doubling times a
re to be calculated from paired samples.