What's The Value of A Pregnancy Calculator?

There are several ways to calculate pregnancy due date. One is to use an online pregnancy calculator. With an online pregnancy calculator, you enter the enter on the screen the first day of your last menstrual period, then click the button. The computer will do the work for you….

But you don't have to use a pregnancy date calculator to determine when your baby is due. You can easily do it yourself, using the same information (first day of your last period) and looking on a calendar. If you add 40 weeks (or 280 days) to that date, you will get to the approximate date your baby will be born.

How accurate is this date? Only a small percentage (5%) of women deliver on the due date that a pregnancy calculator gives, so not all that accurate. Babies are born when they are "done". The window for an "on time" delivery ranges from two weeks before the "due date" until two weeks after the "due date" – thus, any date within a whole 4 weeks fits within the definition of "on time."

What Other Calculations Can Be Done On A Pregnancy Calculator?

Some pregnancy calculators will tell you the gestational age of your baby. This calculation can be made manually, without a pregnancy calculator, by simply counting forward from the first date of mother's last period. Note: gestational age is not calculated from the date of conception, as one might think! Another way to get the gestational age is to have an ultrasound. This can be done as soon as 5-6 weeks after the last menstrual period. As a test of gestational age, the ultrasound is much more accurate during the first half of a pregnancy, between weeks 8 and 18. Ideally, the gestational age is calculated using the first date of the mother's last menstrual period, and measuring on an ultrasound for accuracy.

Many women are interested in knowing the likely date of conception. The conception date can also be found, with or without a fancy pregnancy calculator. For a typical pregnancy, you can assume the conception occurred between 11 and 21 days after the first date of their last period. While that is still a big window, for many women that is the closest to an accurate date of conception they will be able to get.

What Makes Using A Pregnancy Calculator Less Accurate?

A pregnancy calculator is only as accurate as the information given it and the baby's own growth. For some women, their irregular periods (or if they can't remember the first day of their last menstrual period) make it almost impossible to know accurate dates. Also, if the baby is larger or smaller than expected for their age, they can confuse the issues of dates and ages. Sometimes, too, the uterus is not the expected size or it is higher than expected. In these instances, even the midwife or doctor can be unsure, and sometimes will request an ultrasound to confirm dates and get a more accurate gestational age.