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When using in vitro fertilization, the estimation of the due date is generally more precise than calculating the due date based on natural conception, since the exact transfer date is known. Using conception date to estimate due date is similar to using the last menstrual period, except for a difference of about two weeks in the point of measurement, based on the timing between the last menstrual period and the date of conception. It is a simple process that can be performed quickly and easily, that has no known risk to babies, and can be an accurate estimate of the due date early in the pregnancy. Thus, the due date is usually estimated by calculating the date that is 40 weeks from the start of a woman's LMP.Įstimating due date based on ultrasound involves the use of soundwaves to look inside the body and compare the growth of the fetus to typical growth rates of babies around the world. In terms of gestational age, pregnancies typically last between 37 and 42 weeks, with 40 weeks often being used as an estimate in calculations. Although there is some debate regarding when pregnancy technically begins, whether at fertilization of the egg (conception), or when the egg adheres to the uterus (implantation), gestational age does not vary based on different definitions of pregnancy since it is based on LMP. The default for this calculator bases the calculation on a woman's last menstrual period (LMP), under the assumption that childbirth on average occurs at a gestational age (age of a pregnancy calculated from the woman's last menstrual period) of 280 days, or 40 weeks. 1ĭue dates can be estimated using a number of different methods, including the last menstrual period, ultrasound, conception date, and IVF transfer date. While the due date is often estimated as a single date, it can be helpful to consider a range of due dates, since only 4% of births occur on the estimated due date.
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The due date, also known as the estimated date of confinement, is an estimation of when a pregnant woman will deliver her baby. Related Pregnancy Calculator | Pregnancy Weight Gain Calculator Estimation of due date
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