no exercise will not stop ovulation or fertilization. the only case were exercise could cause an interruption in ovulation is if you have become underweight and experience an absent menstrual cycle from the lack of fat in the body. women need a certain level of fat to have a menstrual cycle.
does exercise (1 hr of yoga and 30 to 45 min on eliptical 3-4 times a week) prevent ovulation and/or fertilization?