Is it possible to get pregnant from having sex one week before menstruation?

　　Before the menstrual period, that is, one week before the onset of menstruation, having sex generally does not lead to pregnancy if the menstrual cycle is regular and ovulation is normal. However, if the menstrual cycle is irregular or ovulation is delayed, pregnancy may occur. Detailed analysis is as follows:

　　For women with regular menstrual cycles, ovulation usually occurs approximately 14 days before the next menstrual period. One week before menstruation typically falls after the ovulation period, and the egg has usually lost its fertilization capability by then, making the chance of pregnancy low. In such cases, the ovaries temporarily do not release mature eggs, so sperm cannot combine with an egg, resulting in a low probability of conception.

　　For women with irregular menstrual cycles, ovulation timing is unstable and may be delayed. If the week before menstruation happens to coincide with the ovulation period, having sex can result in pregnancy. Moreover, sperm can survive for several days within the female body. If ovulation occurs slightly later, the sperm may meet and combine with the egg, leading to conception.

　　If not prepared for pregnancy during sex, reliable contraceptive measures should be taken. Relying on the safe period for contraception should be avoided to prevent unintended pregnancy.