When you’re pregnant, you have so many questions. One that likely pops into your brain early on are questions about your delivery date. When can you expect to give birth to the tiny being growing inside you? It’s so hard to wait! While there’s no sure-fire way to say when you’ll deliver the baby you’re so anxious to meet, pregnancy calculation can give you some idea. The day you’re expected to deliver is referred to as the “estimated date of confinement,” abbreviated as EDC.
To calculate your EDC, you must know the first day of your last menstrual period. Armed with that information, simply add 280 days to that date. This will give you a rough idea of when spontaneous delivery should occur. This method of estimating your estimated due date makes some assumptions. It assumes you have regular, 28-day menstrual cycles and that you ovulate mid-cycle, around day 14.
If you have irregular periods or don’t ovulate around the 14th day, pregnancy calculation is less accurate. What if you undergo in-vitro fertilization? Simply add 266 days to the date fertilization took place. If you want to take the easy route, there are pregnancy calculators and pregnancy wheels to help you determine your EDC quickly.
How Accurate is Pregnancy Calculation?
Don’t rely too much on the EDC as an indicator of when you’ll deliver. Only about 5% of babies are actually born on the estimated due date. However, the calculated EDC is usually accurate within two weeks of the day you actually give birth. Therefore, you could deliver as early as two weeks before your EDC or two weeks after and still be within the expected range.
Other Ways to Estimate Your Due Date
Pregnancy calculation isn’t the only way to get an idea of when you’ll deliver, nor is it necessarily the most accurate. If you get an ultrasound early in pregnancy, the results will give a good idea of when you’re likely to deliver. From the ultrasound results, your doctor can measure the length of your baby and the size of your gestation sac. Based on this data, they can make a prediction. However, your doctor may or may not recommend getting an ultrasound early on.
Is there another approach? A physical exam is another way to estimate your due date. When you get your prenatal checks, your healthcare providers measures the height of your uterus to guesstimate when you’re likely to deliver. Other less accurate clues of when you’re likely to deliver are fetal movements and when your baby’s heartbeat becomes detectable.
The Bottom Line
You can use a pregnancy calculator or use the simple formula above to calculate your EDC, but don’t expect to nail down the precise day. It only gives you an estimate. Don’t forget, some babies arrive prematurely while others are slowpokes and stay inside the safety of mom’s womb until the last possible moment. Still, pregnancy calculation will give you some idea of when to expect your new baby and it’s a simple calculation to make – but ultimately, your baby will arrive when it’s ready.
NHS Choices. “Pregnancy due date calculator”
Health Line. “How to Calculate Your Due Date”