First Pregnancy? Calculating Your Baby’s Due Date

When you learn you are pregnant for the first time, you will likely start counting down to your due date. Your doctor will give you a certain date, but do not expect this to be exact. In many cases, your baby will come a little before or after this date.  Enjoy your pregnancy as long as you can, and let your baby decide when it wants to come out into the world.

Calculating the Due Date

Your obstetrician will likely use a sonogram to find your due date. This part of obstetrics is not an exact science, however, and you cannot expect this date to be exact. In many cases, the date offered by the ultrasound is off by a few days or more. Much of this depends on the time of your sonogram, the skill of the technician, and the size of your baby.

For the first few weeks of pregnancy, most babies grow at about the same rate. After this time, however, the size of your baby does not correspond with how long it has been in your womb. If you know the date of your last period, you can calculate what your due date is using Naegele's Rule.

Waiting It Out

If your due date arrives, goes by, and you are still pregnant, you and/or the obstetrician may want to induce your labor. This means the doctor will give you medicine to kick-start your contractions in the hospital. This is a good idea if you are two weeks past your due date. If it has not been this long, however, you may want to wait it out a little longer, because your due date is likely off by a week or so.

Your doctor may want to do another ultrasound to make sure your baby is read, and big enough before your labor is induced.

In your last few weeks of pregnancy, your obstetrician may want to see you more often, such as once per week. This allows them to monitor you and your baby to make sure things are progressing as they should be.

If your baby does not come as scheduled, this gives you more time to bond with it, prepare for motherhood, and get your home ready for the new arrival. Even if you have to wait a few days or even a week longer, it will be well worth it when you hold your baby in your arms for the first time.