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A Novel Use of Three-dimensional High-frequency Ultrasonography for Early Pregnancy Characterization in the Mouse

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Urinary hCG patterns during the week following implantation.

P A Nepomnaschy¹, C R Weinberg, A J Wilcox

¹Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA. pablo_nepomnaschy@sfu.com

Human Reproduction (Oxford, England)

|December 18, 2007

Summary

Human chorionic gonadotrophin (hCG) levels rise rapidly in early pregnancy, but the pattern varies significantly between individuals. This study details the average hCG profile and its variability in the first week after implantation.

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Area of Science:

Reproductive Endocrinology
Early Pregnancy Diagnostics

Background:

Human chorionic gonadotrophin (hCG) is a key marker for monitoring pregnancy.
The precise pattern of hCG excretion in the initial week post-implantation requires further elucidation.

Purpose of the Study:

To describe the average profile and variability of hCG concentrations during the first 7 days following estimated implantation.
To analyze hCG excretion patterns in naturally conceived pregnancies.

Main Methods:

Daily first-morning urine hCG concentrations were measured in 142 clinical pregnancies.
Mixed-effects regression models were employed to analyze hCG trajectories and variability.

Main Results:

hCG demonstrated a 3-fold increase from detection to the next day, with a decelerating rate of rise thereafter.
hCG levels followed a log-quadratic trajectory, independent of fetal number, abortion risk, or infant sex.
Later implantation (after 10 luteal days) was associated with slower hCG increase rates.

Conclusions:

While mean hCG exhibits a log-quadratic trajectory in early detectability, significant inter-pregnancy variability exists.
Delayed implantation may correlate with factors that attenuate hCG production by the uterus or conceptus.