What happens if intercourse is done during periods?

Menstruation is the sloughing off of the outermost layer of the endometrial lining as a result of degeneration of corpus luteum. since the released egg during ovulation has ruptured in the absence of fertilization by sperm, intercourse during menstruation does not cause pregnancy. Although, the Ph of the vagina is less acidic during menstrual period, pregnancy still does not occur because there is no egg to fertilize except in rare cases.