Sex after the menstrual cycle

Question
Can I ask if it's okay to have sex on the 2nd day after the red light is over? I don't come in and my periods are irregular but my cycle is not as short as 20 days.
Vu Khanh An (2001)
Hello doctor. The doctor told me that my menstrual cycle is irregular for about 39 40 days, is there any possibility of pregnancy after 3 days of unprotected sex? Looking forward to consulting your doctor. Thank you.
Anonymous question
Hi doctor, I have my period for 2 days and it's over, on the 3rd day I had unprotected sex, so is there any chance of pregnancy? Looking forward to consulting your doctor. Thank you.
Anonymous question
Hello doctor. I got my period on 24/7 and ended on 28/7 and had unprotected sex and went out on 7/30. So far, August 26, I have not had my period. I want to ask the doctor if I am pregnant or not and if possible, how to detect it as soon as possible for timely treatment. (About 1-2 days ago, I tried 3 times the pregnancy test, all showed 1 line). Looking forward to consulting your doctor. Thank you.
Anonymous question

Answer
Having sex on the 2nd day after the red light is over is considered a relatively safe day. For the case of no clear ejaculation but still able to conceive because the male has secreted a mucus and a small amount of sperm has been released into this mucus. Irregular menstrual cycles make it difficult to predict ovulation. Therefore, it is necessary to see a doctor to find out the cause of irregular menstruation and measures to regulate menstruation.