How to Predict the Due Date in Pregnancy

Calculating the due date of delivering the baby is not an exact science. This is because not all women deliver on that predicted date.

In fact, most women deliver sooner or later than that date. Still, it is important to get an idea of when the baby will come in this world. However, just do not be much attached to the date.

40 weeks

Most pregnancies last for almost 38 to 40 weeks since conception. So, the most common way to predict the due date is to add 40 weeks to the day that marked the beginning of your last period. However, it is normal to deliver a week or two after or before this date.

Naegele’s rule

In case you are among the ones with a regular menstrual cycle of 28 days, there are two ways to predict the delivery date. The first way is to apply the simple Naegele’s rule of adding seven days to the 1st day of your previous/last menstrual period and now subtract 3 months from it.

For example, if this day was December 1, 2015, you add seven days (December 8, 2015) and then deduct three months (September 8, 2015). So, the due date is now September 8, 2016.

Pregnancy wheel

The other way is to apply the pregnancy wheel, which most doctors tend to use due to ease of estimation it provides. However, you need to access this wheel.

You start by locating the first day of your previous menstrual period and line it up with the indicator. That’s it! You wheel shows the due date. The wheel is also useful for women having irregular menstrual periods with a cycle of over 28 days. However, this would involve a few simple calculations.


In case you do not remember the first day of your last menstrual period, it becomes necessary to consult your doctor to predict the due date. The doctor would then use an ultrasound to find the date.


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