depends on what you call pregnancy. sperm lives for 48 hours maximum, so it has to reach the egg before that. if the egg is firtilzed is starts its yjourney from the ovaries to the uterus where it will grow. When the fertilized egg arrives at the uterus and stays there, the girl is pregnant. That is a few days after the conception.
Up to five days, sperm can live in a woman's body up to five days.