You can get pregnant if you don’t use contraception during the week before your period.
For women who normally have regular menstruation, the week before menstruation is in the luteal phase, and if unprotected sex occurs at this time, pregnancy will not occur; however, for women who have irregular menstruation, due to irregular ovulation, if ovulation occurs at this time, pregnancy will occur if sperm combines with the egg.
For women who do not have childbearing requirements, it is recommended that they use condoms, intrauterine devices and other measures to prevent pregnancy; if they have reproductive needs, it is recommended that both spouses cohabitate during ovulation to increase the chances of pregnancy, and if necessary, ovulation can be monitored by ovulation tests or ultrasound.