Normal Ranges of Embryonic Length, Embryonic Heart Rate, Gestational Sac Diameter and Yolk Sac Diameter at 6-10 Weeks.
Summary of "Normal Ranges of Embryonic Length, Embryonic Heart Rate, Gestational Sac Diameter and Yolk Sac Diameter at 6-10 Weeks."
Objectives: To construct normal ranges for embryonic crown-rump length (CRL), heart rate (HR), gestational sac diameter (GSD) and yolk sac diameter (YSD) at 6-10 weeks of gestation. Methods: We examined 4,698 singleton pregnancies with ultrasound measurements of CRL, HR, GSD and YSD at 6-10 weeks and CRL at 11-13 weeks resulting in the live birth after 36 weeks of phenotypically normal neonates with birth weight above the 5th centile. Gestational age was derived from CRL at the 11- to 13-week scan using the formula of Robinson and Fleming. Regression analysis was used to establish normal ranges of CRL, fetal HR, GSD and YSD with gestation, and fetal HR, GSD and YSD with CRL. Results: At 6-10 weeks there were significant quadratic associations between CRL, GSD, YSD and gestation and between HR, GSD, YSD and CRL, and a cubic association between HR and gestation. The estimated gestation from CRL was the same as that of Robinson and Fleming for a CRL of 10.2-36.5 mm, but the formula of Robinson and Fleming underestimated the gestation by 1 day for a CRL 7.4-10.2 mm and this increased to 9 days for a CRL of 1 mm. Conclusion: This study established normal ranges for early pregnancy biometry.
Harris Birthright Research Centre for Fetal Medicine and Early Pregnancy Unit, King's College Hospital, London, UK.
This article was published in the following journal.
Name: Fetal diagnosis and therapy
Medical and Biotech [MESH] Definitions
Stage-specific Embryonic Antigens
Cell-surface molecules that exhibit lineage-restricted patterns of expression during EMBRYONIC DEVELOPMENT. The antigens are useful markers in the identification of EMBRYONIC STEM CELLS.
The heart of the fetus of any viviparous animal. It refers to the heart in the postembryonic period and is differentiated from the embryonic heart (HEART/embryology) only on the basis of time.
Heart Rate, Fetal
The heart rate of the FETUS. The normal range at term is between 120 and 160 beats per minute.
An extra-embryonic membranous sac derived from the YOLK SAC of REPTILES; BIRDS; and MAMMALS. It lies between two other extra-embryonic membranes, the AMNION and the CHORION. The allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo.
The initial stages of the growth of SEEDS into a SEEDLING. The embryonic shoot (plumule) and embryonic PLANT ROOTS (radicle) emerge and grow upwards and downwards respectively. Food reserves for germination come from endosperm tissue within the seed and/or from the seed leaves (COTYLEDON). (Concise Dictionary of Biology, 1990)
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