The link between menstrual cycle and due date

The reason why the due date is called the due date is that it is the delivery date predicted in advance for pregnant women. Although this date is estimated, it is almost accurate to the actual delivery time. But how is this due date calculated? There is a certain pattern in this, and this pattern is inseparable from the menstrual cycle. Let’s see how the editor links the menstrual cycle with the expected date of delivery.

How to calculate the expected date of delivery when the menstrual cycle is 40 days

Medically speaking, the number of days of pregnancy is calculated from the first day of the last menstrual period and has nothing to do with the number of days in the menstrual cycle. Due date: Calculated from the first day of the last menstrual period. The due date is the month of that month. If it is greater than 3, subtract 3. If it is less than 3, add 9 to get the month of birth. Date: If calculated according to the lunar calendar, the date of the last menstrual period plus 14 days is the date of birth. If calculated according to the Gregorian calendar, the date of birth is calculated by adding 7 days.

The method of calculating the expected date of delivery is: it can be calculated based on the menstrual period. The entire gestation period is 40 weeks, or 280 days. Starting from the first day of the last menstrual period, the calculation method is the month of the last menstrual period plus 9 or minus 3, and the date is the day plus 7, and you can get the month and date of the expected delivery date. Under normal circumstances, three B-ultrasounds are enough.

How to calculate due date when menstruation cycle is irregular

1. Calculate according to the date of fetal movement. Generally speaking, fetal movement begins 18 to 20 weeks after pregnancy. This can be used to calculate the expected date of delivery. The calculation method is: the expected date of delivery for primiparas is the day of fetal movement + 20 weeks; the expected date of delivery for multiparas is the day of fetal movement + 22 weeks.

2. Calculate according to the basal body temperature curve. The last day of the low temperature segment of the basal body temperature curve can be regarded as the ovulation day. Counting back 264 to 268 days from the ovulation day, or adding 38 weeks, the expected date of delivery can be calculated.

3. Calculated based on B-ultrasound examination. When doctors perform B-ultrasound examinations on pregnant women, they can estimate the gestational age and calculate the expected date of delivery based on the measured biparietal diameter, crown-rump length and femur length.

How to calculate the expected date of delivery when the menstrual cycle is 40 days? How is the due date calculated? How to calculate due date if menstrual cycle is irregular? All three questions tie today's topic closely together. In short, no matter what kind of menstrual cycle you have, there is a way to calculate your due date.