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Calculating Your Due Date

Many new moms-to-be, whether expecting a first baby or beyond, find it hard to figure out the baby’s exact due date prior to seeing her doctor or midwife. When it can sometimes take weeks to get in for your first prenatal appointment, the waiting game can seem long and never ending.

Babies Online wants to make it easier for every woman to find out her baby’s due date prior to that first appointment, by offering both helpful information and our fantastic due date calculator which is free for you to use.

Due Date Calculator
What was the first day of your last period?

The first thing you need to know in order to use our due date calculator is the first day of your last menstrual cycle. It is very difficult to get an estimated due date, without an early ultrasound, even from your doctor, unless you know this date. Calculators take into account your last period and assume conception took place a week after that date. They then add nine months to that date to give you the estimated due date.

It is important to remember that these calculations are just estimates – you should not count on your baby coming on that day. Only about 20% of babies come on the actual due date that was calculated. The other 80% are split between coming before the estimated due date, and after. Since a pregnancy is considered full term at 37 weeks (3 weeks before the calculated due date) and is generally not considered to be dangerously overdue till after 42 weeks (2 weeks after the calculated due date), this early date gives you an estimated time span of when your baby will come.

As your pregnancy progresses and you have ultrasounds done to check your baby, it is possible that your doctor will update and change your due date at which to reflect the rate at which your babyhas grown, using measurements taken in the ultrasound. In most cases, this will only change a few days or a week in either direction.

After you get that positive result from your pregnancy test, knowing the date your baby should be born gives you something to focus on, and to look forward to for the months to come. It is likely that for many women, the next nine months will seem the longest nine months of her life. Have no fear though. Your baby will arrive, whether he makes an appearance on your calculated due date or surprises you on another date.

Do you know your baby's birth stone? Birth Flower? How about when you'll be handing over the car keys? Check out our popular Fun Birthday Facts Calculator to discover fun trivia about your baby's birth or due date!

What is your due date or baby's birthday

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4 Comments on "Calculating Your Due Date"

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8 years 4 months ago

hi i had sex 10 jan , its only the 13 jan ive bin having reli bad cramping pains , & im due on round about now & i havent beein having the signs in coming on my period .. could i be pregnant ??

8 years 10 months ago

I just found out I was pregnant. I am so confused! The first day of my last cycle was on June 1, 2010. I still haven’t received my due date yet by my doctor. When they did the ultrasound my baby wasn’t even developing yet. Is everything ok? Should I worry? How many weeks am I? When is my baby due? Can someone please help me!!!!

9 years 7 months ago

It is ok, these type of things are more of an estimate more than anything. the closest result you are going to find is from you dr. when they do the sonograms (ultrasounds) they can really tell by the babys growth, length size and features and blood tests. so go with what your dr says, dont stress :o)

10 years 3 months ago


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