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How Doctors Calculate and Determine Your Due Date

For a pregnant person to know when their pregnancy is due, they must have visited the hospital a couple of times before the doctors determined the due date. Calculating and determining the due date is not rocket science. Normally, pregnancy lasts for about 280 days (40 weeks) from the first day of your last menstrual period. Basically, when you get tested and confirmed pregnant, doctors will ask for the first day of your last menstrual period after you’ve answered, then they begin to count from that day. Only a few women deliver on their due date, this is because pregnancy doesn’t actually start on the first day of your last period as opposed to the doctor's calculation. The doctor's calculation however gives an estimated time to when your pregnancy is due so that you know when to start expecting your child. In this article, we highlight ways doctors determine how a pregnant person is due for delivery.

  1. Last Menstrual Period: Normally, a person begins to suspect that they are pregnant when they no longer see their period. Nobody knows the real day you conceive, not even the doctors. However, knowing the first day of your last menstrual period will go a long way in giving an idea of the period you got pregnant and when you should be expecting your baby. Doctors could also calculate the due date by adding 40 weeks to the first day of your last menstrual period. They add 40 weeks because a normal pregnancy should last for 280 days. However, most women deliver within 1 to 14 days of their due date.
  1. Uterus Size: Doctors can also determine the due date through the size of your uterus. When a person is about 12 weeks pregnant, the top of the uterus can be felt above the pelvis. If your doctor examines you and feels the top of your uterus above the pelvis he can confirm that you are about 12 weeks pregnant. However, after the pregnancy reaches 18 weeks, the distance between the pubic bone and the uterus is likely to be the same as the number of weeks since your last period (in centimeters). Then when the pregnancy is 20 weeks old the uterus would be as high as your belly button. Therefore examining the uterus will also make your doctor or midwife determine the changes, and calculate your due date.
  1. Ultrasound Scan:

    Ultrasound testing or ultrasound scan is one of the most effective ways doctors can determine how old a fetus is and when the baby is due for pregnancy. If you cannot remember your menstrual period or your last ovulation, taking an early ultrasound test will help find out your due date. Some doctors would rather wait until the pregnancy is about 20 weeks old before doing an ultrasound. If the doctor will not compromise with an earlier scan, try to find support groups who provide pregnancy ultrasound services in Bloomsburg to do it instead. During an ultrasound test, a device called a transducer is placed on your belly and moved around. This device then sends sound waves that bounce off the fetus. The sound wave is then converted into a picture displayed on a computer’s screen. The picture is a representation of how the baby is forming in your belly. The size of the fetus would however help the doctors determine and calculate your due date.

Having An Easy Pregnancy

If you want to have an easy pregnancy, you must take prenatal examinations seriously.

Do not be far away from your doctors so they can catch any changes and advise you on how to go about it. If you have plans to travel while you’re pregnant, it is important to get travel insurance. This is necessary because anything can happen during the trip, so you want to ensure that your baby is safe and insured.

Before or during your delivery, if you are having trouble breathing, your doctor might recommend that you will need to buy oxygen concentrator. An oxygen concentratorin awe you run out of breath. An oxygen is a device that draws air from the surrounding, purifies it, and delivers oxygen. You can get a portable concentrator if your mobile or a large one to be installed at home.

Finally, ask your doctors for healthy foods for your developing baby. You don’t want to take anything that would cause harm to your unborn child.


The joy of every mother is to successfully go through a pregnancy without any issues and deliver the child safely. For this to be possible you have to be close to your doctors, in fact, the best time to stay closest to your doctor is when you are expecting a baby because so many changes would happen in your body during this period. For you not to make the wrong decision or take the wrong drugs you should always be within the reach of your doctor. Now that you know how doctors calculate the due date, you know that the first day of your last menstrual period is when you start calculating. However, you have to be sure that you are pregnant before you begin calculating.

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