First day of last period Most pregnancies last around 40 weeks (or 38 weeks from conception), so typically the best way to estimate your due date is to count 40 weeks, or 280 days, from the first day of your last menstrual period (LMP).
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Knowing the exact day of conception is a difficult thing. Sperm can live in a woman's body for up to five days, making it impossible to calculate exactly when conception occurred. It is not a fine science. In addition, women ovulate anywhere from 11 to 21 days after the first day of their last period.
Is It Possible to Know Exact Day You Got Pregnant? | Assure Omaha
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Typically women ovulate about two weeks after their menstrual cycle starts, so the best way to estimate your due date is to count 40 weeks, or 280 days, from the first day of your last menstrual period. Another way to do it is to subtract three months from the first day of your last period and add seven days.
Due Date Calculator | Conception Information | Choices of the Heart
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