There are various types of pregnancy due date calculator that health professionals can use to determine the due date of a baby. In the very early stages of a pregnancy the most frequently used types of pregnancy due date calculator involve using the date that a woman had her last menstrual cycle and the usual length of her period. This type of pregnancy due date calculator is only a rough estimator of when a baby is actually due. A number of factors make this type of pregnancy due date calculator being less than accurate. The most important factor is using this form of pregnancy due date calculator is that a woman needs to know the date of her last period. If she has missed more than one menstrual cycle before she thinks that she may be pregnant then her accurate recollection of the date of her last menstrual cycle is not very reliable. A woman may not have a period or may suffer from irregular menstrual cycles and this makes the date of her last period even less accurate for the pregnancy due date calculator.
The pregnancy due date calculator not only works with the inaccurate information provided about the date of a woman's last menstrual cycle but also assumes that every woman has a menstrual cycle of 28 days. This means that in the early stages of pregnancy a pregnancy due date calculator can only used to produce an estimated due date for the baby. Of course, your health professional will use this type of pregnancy due date calculator in the initial stages of your pregnancy to give a general timeline for the pregnancy but it is important to remember that the estimated due date given can be extremely inaccurate.
After approximately ten weeks a woman is usually given a scan to help more accurately assess the length of the pregnancy. The size of the growing foetus can be used from these ultrasound scans to provide various measurements which are used in a pregnancy due date calculator to determine the estimated due date more accurately. For example, the length of the foetus and the size of its head at various stages throughout the pregnancy are measured and these provide more accurate figures for a pregnancy due date calculator to be able to predict the date of birth. This is because a foetus grows at a predicted rate and it is by using these measurements that a pregnancy due date calculator can give the woman the best estimate as to when her baby is due.
Blood tests that measure that amount of hCG in a woman's blood can also be used by a pregnancy due date calculator. Blood and ultrasound results are the best sources of data for a pregnancy due date calculator and are likely to provide a much more accurate due date compared to any type of pregnancy due date calculator based solely on a woman's previous menstrual period.
