Measuring the baby using ultrasound is most accurate in early pregnancy. The best time to estimate gestational age using ultrasound is between the 8th and 18th weeks of pregnancy.
The most accurate way to determine gestational age is using the first day of the woman’s last menstrual period and confirming this gestational age with the measurement from an ultrasound exam.
A normal pregnancy can last anywhere between 38 and 42 weeks.
If you want to, you can view a sample due date report.
Gestational age is calculated from the first day of the mother’s last menstrual period and not from the date of conception.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions.
This pregnancy due date calculator will give you a rough idea of when your baby should be born.
If you know the date of the first day of your last menstrual period (LMP), or have already had your first ultrasound scan, you can use this tool.
Use our Pregnancy Calculator to calculate these dates for you.
If the mother has a regular period and knows the first day of her last menstrual period, gestational age can be calculated from this date.