Pregnancy is calculated from the first day of the last menstrual period (LMP) for several reasons. Firstly, it is a convenient and reliable method for determining the due date of pregnancy. The LMP is used as a reference point because it is the starting point from which the gestational age of the fetus can be calculated.
Secondly, the LMP is a reliable indicator of the start of pregnancy because ovulation, when the egg is released from the ovary and fertilized by sperm, typically occurs two weeks after the start of a woman’s menstrual period. As a result, the LMP can provide a rough estimate of when conception took place and the gestational age of the fetus.
Additionally, the LMP is a simple and non-invasive method of estimating the due date of a pregnancy, which makes it an accessible option for women and healthcare providers around the world. It is also a method that has been used for many years and is well-established in medical practice.
In conclusion, pregnancy is calculated from the last menstrual period because it is a convenient, reliable, and accessible method for determining the due date of pregnancy. By using the LMP as a reference point, healthcare providers can estimate the gestational age of the fetus and provide expectant mothers with important information about their pregnancy.