With 40 weeks (280 days) as the gestation period, calculate the number of weeks of pregnancy from the expected delivery date.

Assuming 40 weeks (280 days) of pregnancy, calculate the number of weeks of pregnancy by counting backwards from the expected date of birth.

The specified day is displayed in weeks and days from the last menstrual start date and in days.

Gestation period

Pregnancy period is counted as 1 month from 0th week to 3rd week, 2nd month from 4th week to 7th week, and so on.

The 1st to 4th month of pregnancy is called the early stage of pregnancy, the 5th to 7th month of pregnancy is called the middle stage of pregnancy, and the 8th month and beyond is called the third stage of pregnancy.

Time of birth

A full-term birth is defined as a birth between 37 weeks 0 days and 41 weeks 6 days of gestation.

Fetuses born at this time are fully mature and therefore the best time to give birth safely.

A premature birth is defined as a birth between 22 weeks 0 days and 36 weeks 6 days of gestation, which is earlier than a full-term birth.

Fetuses born during this period are more likely to develop physical disabilities.

If the pregnancy is less than 22 weeks, it is called a miscarriage and it is almost impossible for the fetus to survive.

Anything after 42 weeks 0 days is called postterm.

An oversized fetus or a malfunctioning placenta increases the risk of fetal harm.