Urinary hCG patterns during the week following implantation

Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA.
Human Reproduction (Impact Factor: 4.57). 03/2008; 23(2):271-7. DOI: 10.1093/humrep/dem397
Source: PubMed


Human chorionic gonadotrophin (hCG) is used to monitor pregnancy status. Yet the pattern of hCG excretion in the first week following implantation has not been adequately described. Therefore the aim of this study was to describe the average profile of hCG and its variability during the 7 days following estimated implantation in a population of naturally conceived pregnancies.
We measured daily hCG concentrations in first-morning urine for 142 clinical pregnancies from women with no known fertility problems. Mixed-effects regression models were used to estimate the hCG trajectory and its variability in relation to pregnancy outcomes.
hCG rose 3-fold between the day of detection and the next day (95% CI = 2.7-3.4). The relative rate of rise decreased thereafter, reaching 1.6-fold (95% CI = 1.5-1.8) between days 6 and 7. HCG levels followed a log-quadratic trajectory, and the patterns of rise were unrelated to number of fetuses, risk of spontaneous abortion or sex of the baby. Later implantations (after 10 luteal days) produced slower rates of increase.
Although mean hCG follows a log-quadratic trajectory during the first week of detectability, there is high variability across pregnancies. Later implantation may reflect characteristics of the uterus or conceptus that slow hCG production.

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Available from: Pablo A Nepomnaschy
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    • "Wilcox et al. [1999] associated delayed implantation in humans with adverse pregnancy outcome, although the specific causes of pregnancy losses in their study were not evaluated [19]. Surprisingly and conversely to that human study, in animals delayed implantation appears to enhance the developmental potential of the embryo, as shown in rodents [5], pigs [6], rabbits [7] and sheep [21]. This increased developmental potential of mammalian embryos undergoing ED may be due to their cellular repair while being arrested (discussed in 9). "
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    ABSTRACT: When a competent blastocyst stage embryo finds itself in an unreceptive uterus, it delays development. In around one hundred species representing various orders, this delay is known to be reversible, but this phenomenon - termed embryonic diapause (ED) - is not considered a general characteristic of all mammals. Recently, however, we demonstrated that a non-diapausing species, the sheep, is capable of ED, suggesting the hypothesis that this is in fact an ancestral trait common to all mammals, including humans. In spite of the obvious difficulties in testing this idea, we propose a combination of indirect observations on human fertility patients, and direct study of the embryos of non-human primates. Support for our hypothesis would require revision of obstetric interventions routinely performed when a human pregnancy extends beyond the due date.
    Full-text · Article · Sep 2013 · Reproductive Biology and Endocrinology
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    • "This was calculated for Day j as exp[average(ln hCG j − ln hCG 1 )], where 'ln(hCG) 1 ' indicates the natural log of the hCG concentration on Day 1, which is the day of implantation, 'ln(hCG) j ' indicates the natural log of the hCG concentration on Day j, which ranges from 2 to 7, and the 'average' is taken across pregnancies. The absolute hCG curves from this population have been previously published (Nepomnaschy et al., 2008). In addition, that paper examined the association of hCG curves with twin pregnancies, pregnancy loss after 42 days gestation and infant sex. "
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    ABSTRACT: BACKGROUND Late implantation and the pattern of early rise in hCG have been associated with early pregnancy loss. We explored factors that might be predictive of these markers of poor embryonic health in spontaneously conceived pregnancies.
    Preview · Article · Feb 2011 · Human Reproduction

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