There are several ways to calculate when the long-awaited baby will be born.
• If menstruation came regularly before pregnancy, then the first day of the last “critical days” is taken as the starting point. To this date you need to add 9 regular calendar months and another week. This will give you (approximately) the day on which you can expect the baby to be born. You can do it differently: from the first day of your last period, count back 3 calendar months and then add a week.
• You can calculate the baby's due date based on the last ovulation. To do this, you need to take as a starting point the number on which your period should have started, but did not. From this number you need to count back 2 weeks and then add 273 days to this date.
• If a woman does not remember the date of her last menstruation, or she does not have them regularly, then you can use the day of the baby’s first movement as a starting point. To this day you need to add 20 weeks for primiparous women, 22 weeks for multiparous women.
• One of the most accurate methods that helps calculate the gestational age (and with it the due date) is ultrasound. It is especially convenient in the early stages. In the second and third trimesters, the child’s development may be delayed, and then the child’s size will look shorter.
Doctors use different methods to determine the expected date of birth and all the resulting calculations are recorded in the chart.