How to know your Due Date

The normal duration of pregnancy is 40 weeks from the first day of the last menstrual period (LMP) you had. Thus it is important to remember your LMP. If you know this date and your cycles are regular, you can determine your due date sitting at home.

Our ‘DUE DATE CALCULATOR’ will do it for you in a jiffy. Click here

If your cycles are regular and 28 days long, then add 9 months and 7 days to the first day of your LMP. For example, if your LMP began on March 4, then your expected due date (EDD) would be December 11.

This formula works for cycles 28 days long +/- 7 days, i.e. from 21 to 35 days. However the same number of days will have to be added or subtracted from the due date. For example, if your cycles are 30 days long and your LMP is march 4, then your EDD as above is Dec 11+2 days = Dec 13.

BUT IF I DONT REMEMBER MY LMP, WILL I NEVER KNOW WHEN TO EXPECT MY BABY?

No! Don’t panic. What are doctors for? When you visit your doctor for antenatal checks he will calculate your due date using one of following methods.

  1. Abdominal Examination: The doctor will examine your abdomen to look for size of the enlarged uterus, at each of your visits. The uterine size depends on your baby’s growth. From this he will get an idea of how old your baby is and when can you expect to deliver. This method can only give a rough idea and cannot pinpoint a specific date.


  2. Ultrasound Scan: One of the reasons for frequent ultrasound scans especially in the last trimester, besides knowing the normalcy of the fetus, is to monitor baby’s development and provide a much more accurate due date. This method is superior to other methods because it is possible to examine and measure each of the baby’s organs and limbs on ultrasound. These measurements can then help in determining the stage of fetal development, and consequently the due date. It is possible that each of your ultrasound scans gives a different due date. The date computed from your last ultrasound scan is likely to be the most accurate. Again, remember that these dates are simply estimates, and therefore are only indicative of the actual delivery date.

CAN DIFFERENT METHODS GIVE DIFFERENT DUE DATES?

Yes. Each method will most probably give a different due date, but most of the time, they will vary only by a couple of days. However, if the woman has had an irregular menstrual cycle, or her cycles were very long or very short, then the LMP method will not be accurate. In this case, an ultrasound scan will be most accurate.

CAN I ALSO PLAN TO HAVE MY BABY ON A PARTICULAR DAY?

Yes, you can try to plan your baby, but a particular day may not be possible. You may be able to get right the month and the week depending on due date. However, remember, your menstrual cycles and ovulation times would have to co-operate! Click here for JUSTEVES to help you plan your baby.