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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Uterus is receptive for implantation for how many days after feilization -
assistant
The correct answer is  Superfetation is the feilization of two ova released in two different menstrual cycles. The nidation and development of one fetus over another fetus is theoretically possible until the decidual space is obliterated by 12 weeks of pregnancy. Ref : Dutta book of obstetrics 8th Ed