How to know how many days pregnant? To know how many days pregnant according to the last menstrual period calculation, as follows: 1, usually normal menstruation, ovulation is normal, according to the last menstruation to calculate. 2, ultrasound to understand the size of the intrauterine gestational sac, to estimate the time of conception, and use this to estimate the expected date of delivery. If the menstrual period is irregular, it can also be calculated according to the time of conception at intercourse, plus two weeks. Generally most women will experience nausea, vomiting, loss of appetite, dizziness, wanting to sleep, or a sudden desire to eat certain foods, fruits, and something acidic around 36 days of pregnancy.3. Ultrasound is done after 40 days of menopause, which is relatively accurate in calculating the number of days to conception. During pregnancy, pay attention to balanced nutrition and combine work and rest.