How can fertilization go awry?

• Too many sperm = dispermy or triploidy

  • Leads to spontaneous abortion in most cases.

• Infertility

• Bad timing:

  • The sperm can only survive 48 hours within the female genital tract.
  • In vitro studies show the ovulated egg cannot be fertilized after 24 hours.

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Ectopic pregnancy:
If fertilization occurs outside the oviduct, the next step of embryonic development, implantation, may occur in the wrong location as well
If the oviducts are scarred due to an STD or other pathology, a fertilized ovum may implant in the fallopian tube