Pregnancy Information Pregnancy Calculator

My due date was August 9th. As a new mother, I fully expected my baby to make her appearance on that day. After all, the pregnancy calculator said that my conception occurred on November 2nd. My doctor warned, “They don’t always come out on their due date,” but my instinct said otherwise. I remember sitting on the sofa on that hot August night thinking, “Well, if you’re not going to come out now, just forget it.”

I tried every mythical suggestion to trigger my labor-things like eating pizza with extra garlic or walking up and down the street with one foot on the curb and one in the gutter. No baby. Six days later, on August 15th, my daughter arrived in her own time, in her own way. Babies come out when they’re ready. But my so-called due date is still an indelible memory.

Estimation of the Due Date

The due date is considered an estimated date of delivery. Doctors estimate due dates based on the date of the last menstrual period. The first day of the last menstrual period (LMP) is considered day zero. Most women ovulate two weeks after the first day of their LMP. Ovulation occurs when an egg is released from the ovary. This is the most likely time for conception to take place.

Types of Pregnancy Calculators

The most accepted way to date a pregnancy is with a pregnancy calculator. Many Internet websites have pregnancy calculators to help determine an approximate due date. The date of the last menstrual period is submitted and the final results of your projected due date appear on screen.

Doctors’ offices use disc-shaped pregnancy calculators that help estimate the due date based on the LMP and date of conception. These handy pregnancy calculators can also be used to some extent to plan your family.

Calculating Due Dates

Pregnancy calculators use Naegele’s rule to estimate the date of delivery. Naegele’s rule subtracts three months from the LMP then adds one year and seven days. For example, an LMP of July 1, 2004 would have an estimated delivery date of April 8, 2005. This number comes to 280 days after the LMP.

Why Due Dates Are Important

The importance of due dates has less to do with the final moment of birth and more to do with the progress of the pregnancy. Doctors rely on due dates and approximate date of conception to estimate the age of the fetus and to gauge developmental milestones of the baby. Often, an ultrasound is done in the first trimester of the pregnancy to determine the actual gestational age. Once the gestational age has been determined, a pregnancy calendar keeps track of landmarks of fetal development.

For the mother, the due date is a reminder of the importance of prenatal care. Getting the proper nutrition and nutrients before and during the pregnancy has been shown to significantly reduce the risks of certain birth defects. But the due date is also the “light at the end of the tunnel.”

Pregnancy Calendar and Developmental Progress

Doctors and mothers-to-be can track the progress of fetal development with a pregnancy calendar. A pregnancy calendar can be divided into trimesters, months or weeks and describes how the fetus is developing at these times.

Pregnancy calendars are a good way for women to track development of the baby and connect their own signs and symptoms of pregnancy with development. The pregnancy calendar also provides a marker for women as they anticipate milestones like hearing the baby’s heartbeat for the first time or finding out the sex of the baby.


Beers, M. H.