When having sex, using condoms is generally less likely to result in pregnancy. The chance of a woman not getting pregnant with a condom is generally over 90%, and only in rare cases does an unplanned pregnancy occur. If a condom fails or has a small hole at the top, the sperm can spill into the woman’s vagina, and it happens to be the woman’s ovulation period, the egg and sperm can combine and develop into a fertilized egg, so the woman can become pregnant. If a woman has nausea or vomiting after a delayed period, she should go to the hospital for a gynecological ultrasound and blood test for blood chorionic villus promoting hormone levels, and if an unwanted pregnancy occurs, she should be given an early termination. The effectiveness of contraception is not 100%, regardless of the contraceptive measures used by women. Therefore, it is important to check HCG or ultrasound promptly after delayed menstruation to clarify if pregnancy is present.