The last menstrual period was on April 15 and the due date is January 22 of the following year. The due date is calculated by subtracting 3 or adding 9 to the month and adding 7 days to the date of the last menstrual period. If a woman has irregular periods, an ultrasound can be performed early in the pregnancy to assist in estimating the due date. If there is a large difference between the two, the due date can be corrected based on the ultrasound results. Proper timing and frequency of prenatal checkups can ensure the quality of care during pregnancy. Obstetric examination includes taking medical history, physical examination, obstetric examination, auxiliary examination, and health guidance and education. Normal pregnant women should have at least eight antenatal checkups, and the number of checkups can be increased appropriately if there are high-risk factors. Mothers should take the initiative to cooperate with antenatal check-ups, follow medical advice on health care, and successfully complete the labor process.