There are a different number of types of pregnancy calculator that can be used to determine the due date of a baby. In the early stages of a pregnancy, most of the sorts of pregnancy calculator rely on the date that a woman had her last menstrual cycle. This means that a pregnancy calculator is only an estimator of when a baby is due.
There are a number of reasons why this type of pregnancy calculator cannot be completely accurate. Obviously, a woman needs to remember the date of her last period. If she was not planning on becoming pregnant then a woman may have missed more than one menstrual cycle before she thinks that she may be pregnant. There are a lot of reasons why a woman may not have a period and these can prevent her remembering the last time that she actually had a menstrual cycle exactly.
The pregnancy calculator can only work with the information provided about the date of a woman’s last menstrual cycle and a woman who has irregular periods may also be unable to provide an accurate date of her last period. So in the early stages of pregnancy, a pregnancy calculator is only used to produce an estimated due date for the birth. Your health professional will use this type of pregnancy calculator in the initial stages of your pregnancy but the estimated due date can be extremely inaccurate.
Once a woman has been pregnant for approximately ten weeks she can be given a scan to determine the size of the growing fetus. These ultrasound scans can be used to provide various measurements which are used in a pregnancy calculator to determine the estimated due date more accurately. The length of the fetus and the size of its head at various stages throughout the pregnancy are measured to provide more accurate figures for a pregnancy calculator to predict the date of birth.
It is this type of pregnancy calculator that is likely to provide the due date more accurately than any type of pregnancy calculator based on a woman’s previous menstrual period. The fetus grows at a predicted rate and it is by using these measurements that a pregnancy calculator can give the woman the best estimate as to when her baby is due. Ultrasound scans are given at various intervals during the pregnancy to check the progress of the baby and also to confirm the estimated due date that has been given by a pregnancy calculator.