What is gestational age?
You've used Flo's online due date calculator to predict when you're likely to give birth and how far along you are. But if you're still not completely clear on what gestational age actually is, we're here to help.
Gestational age describes where you are in your pregnancy. It’s measured from the first day of your last menstrual period (LMP) to the current date, typically in weeks. Usually, pregnancies last anywhere from 38 to 42 weeks; babies born before the 37-week marker are considered premature.
How to understand gestational age
LMP refers to the first day of your last menstrual period. Health care providers measure pregnancies in weeks starting from the first day of the LMP. If your period is regular and lasts 28 days, and if ovulation generally happens on day 14 of your cycle, then conception probably took place about two weeks after the LMP. For gestational age counting, these two weeks are added to a pregnancy as a simpler method than trying to track from ovulation or fertilization.
Nevertheless, this estimation is not always accurate. It doesn't take into account factors like changes in the menstrual cycle, variations in ovulation, and imperfect recall by patients.
A due date calendar or calculator can help pregnant people determine their baby’s due date.
To calculate your due date, add 280 days (40 weeks) to the first day of your LMP (if you have a 28-day cycle).
Different calculators can help determine your due date based on ovulation, date of conception, and ultrasound data. Specific calculators can predict the due dates of people who are using assisted reproductive technologies and embryo transfer.