Many women also find it easier, when asked how pregnant they are, to answer in weeks instead of months, because pregnancy is generally a count down. “I am 24 weeks, only 16 weeks to go!” The most general deduction by a bystander would be that the woman is already six months pregnant, when in actuality, per the Gregorian calendar that most of the world lives by, she is only about five and a half months pregnant.

Women who consider themselves 10 months pregnant usually use this form of calculations:

For those that live by the Lunar calendar, this not only makes sense, but is absolutely correct. The Lunar calendar, which is the four weeks it takes for the moon to go from a new moon, to a full moon and back again, would make a pregnancy last for ten months.

For those that live by the Gregorian calendar, and counting by the date you started your last period (let’s say October 15), you would not be one full month pregnant until November 15 and the calculations generally look like this:

However, neither of these calculations is exactly accurate. The most common way to figure out your due date, including the way that most doctors calculate it, is to add nine months and seven days to the start date of your last menstrual period, which would actually be a week before you would have ovulated with a 28-day cycle. Therefore, if you started your LMP on October 15, you due date would be calculated as July 22, not July 15.

This would make your due date of July 22 be at 40 weeks exactly, or nine months and one week after you started your LMP. This being said, why would someone CHOOSE to be pregnant for ten months?

Another way to look at it is if you consider a pregnancy of 40 weeks to be ten months, and that a year has 52 weeks in it – which you also count four weeks as one month – wouldn’t this mean that your baby would be 13 months old before he turned a year, and you could celebrate his first birthday?

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.

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.