Our objective was to prospectively validate the use of gestational sac (GS), yolk sac (YS) diameter, crown-rump length (CRL), and embryonal heart rate (HR) dimensions to identify early pregnancy loss. This was a prospective cohort study of first trimester pregnancies. GS and YS diameter, CRL, and HR measurements were serially obtained in singleton and twin pregnancies from 6 through 10 weeks’ gestation. Non-parametric tests and logistic regression models were used for comparisons of distributions and testing of associations. A total of 252 patients were included, of which 199 were singleton pregnancies, 51 were twins, and 2 were triplets (304 total fetuses). Fifty-two patients had 61 losses. We built nomograms with the changes of the parameters evaluated in ongoing, as well as in pregnancy loss. In the pregnancies which failed, all the parameters showed significant changes, with different temporal onsets: GS and YS were the first to become abnormal, deviating from normality as early as 6 weeks’ gestation (OR 0.01, 95% CI 0.0–0.09, and OR 3.36, 95% CI 1.53–7.34, respectively), followed by changes in HR, and CRL, which became evident at 7 and 8 weeks (OR 0.96, 95% CI 0.92–1.0, and OR 0.59, 95% CI 0.48–0.73, respectively). Our observations showed that, after 5 complete weeks’ gestation, a small GS and a large YS reliably predicted pregnancy loss. The YS reliably identified the occurrence of a miscarriage at least 7 days prior its occurrence. CRL and HR became abnormal at a later time in pregnancy and closer to the event. These findings have important implications for patient counseling and care planning, as well as a potential bearing on cost effectiveness within early pregnancy care.

Culture with increasing rAMH concentrations caused downregulation of its own, as well as other hormone receptors, and a decreased ovarian cortex cell proliferation. These results help understanding the inhibitory effects of AMH on follicular development.

Administration of recombinant AMH in the peri-transplant period did not protect the initial follicular depletion but decreased apoptosis and cellular activation and regulated stem cell markers' tissue expression. These results aid our understanding of the inhibitory effects of AMH on follicular development and show the benefit of administering exogenous AMH at the time of pre-pubertal ovarian cortex transplant to protect the follicles from pre-activation and premature depletion.

Aim: The yolk sac (YS) has been reported as a reliable predictor of adverse pregnancy outcomes, however, it has always been evaluated cross-sectionally with a single ultrasound per patient. We sought to validate the use of YS dimensions in serial ultrasounds throughout the first 10 weeks of singleton and multiple gestations.Methods: This was a prospective cohort study where YS diameters were serially obtained with 2D ultrasound in singleton and multiple gestations from 5 to 11 weeks. Nonparametric test were used for comparisons with P < 0.05 indicating significance. Results: One hundred ninety-three patients were included, 42 twins (3 monochorionic and 39 dichorionic), 2 triplets (monochorionic twins plus a singleton) and 148 singleton pregnancies (238 total fetuses). There was no difference in YS dimensions in singleton versus multiple pregnancies. Starting at 5 weeks' gestation, the YS increased 0.4 mm (95% CI 0.3-0.5 mm) per week until 10 weeks' gestation. Forty-five fetuses were lost in the first trimester. The risk of pregnancy loss was higher with a large YS until 8 weeks (P ≤ 0.001), while after 8 weeks it was higher with a small YS (P < 0.005). Conclusion: We established a nomogram of YS development during the first 10 weeks of pregnancy. The YS reliably detected pregnancies that ended in loss as early as 6 weeks' gestation. The YS was either smaller or larger than in ongoing pregnancies. While all pregnancies with large YS were lost within 10 weeks, those with smaller YS were lost beyond the first 10 weeks.

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