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the fertilization of an ovum and subsequent development of another embryo (fetus) when one is already present in the uterus, a result of fertilization of ova during different menstrual cycles, yielding fetuses of different ages.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
The presence of two fetuses of different ages, not twins, in the uterus, due to the impregnation of two ova liberated at successive periods of ovulation; an obsolete concept.
Farlex Partner Medical Dictionary © Farlex 2012
Formation or development of a second fetus when one is already present in the uterus, occurring normally in certain vertebrate species.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
superfetationObstetrics Fertilization and subsequent development of a 2nd ovum after the 1st has already implanted in the uterus; superfetation provides the theoretic explanation for the difference in times of delivery of fraternal 'twins'. Cf Superfecundation.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
superfetationThe rare occurrence of two or more fetuses of different ages in a womb that are the result of fertilizations occurring in different menstrual cycles.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005