An egg survives 12 to 24 hours after ovulation, according to the American Pregnancy Association. WebMD notes that sperm can live up to five days inside a woman's body.
About.com explains that due to the lifespan of sperm, fertilization of an egg is possible in a woman who has unprotected sex any time between five days prior to ovulation to one day following the event. This source also states that establishment of pregnancy does not occur until a fertilized egg is implanted in the lining of a woman's uterus. The American Pregnancy Association notes that implantation of the fertilized egg takes place six to 12 days following ovulation.