There is little chance of pregnancy during menstruation.
During menstruation due to the body’s estrogen and progesterone secretion gradually decline, the endometrium blood supply of small blood vessels spasm contraction rupture, endometrial stripping caused by bleeding, the ovaries during menstruation did not ovulate, so there is no egg. At the same time, the endometrial stripping with the menstrual blood out of the body, the fertilized egg is not easy to bed, so the menstrual period pregnancy chances are very small.
However, if a woman is taking drugs to cause endocrine disorders in the body, resulting in irregular menstrual cycles affecting the normal ovulation caused by ovulation abnormalities, which leads to ovulation during menstruation, in this case, pregnancy during menstruation may be possible.
The same period will cause uterine contraction, but also the endometrial debris into the pelvic cavity, resulting in endometriosis, and may also cause pelvic inflammatory disease and vulvodynia, it is recommended to avoid coitus during the menstrual period.