Trimester timeline: calculating pregnancy weeks to months - The Mother Baby Center
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Learn what to expect throughout pregnancy from the first weeks to the final months and how to prepare for delivery at The Mother Baby Center.

The time of pregnancy is calculated from the first day of your last menstrual period (LMP), which is typically two weeks before conception actually occurs. This means the first two weeks of the 40-week count are before fertilization, during which your body prepares for ovulation and a new cycle begins

  • FriendOfDeSoto@startrek.websiteEnglish
    72·
    2 天前

    Does this make any sense?

    Yes.

    First they define pregnancy to start before conception.

    That’s not what’s happening. This is a statistical math problem and the last, reliably known variable is most likely the last period of the person before conception. That doesn’t mean they were pregnant before conception. If neither the date of the last period nor the date of conception are known, they use a different method, probably ultrasound picture comparisons, and add a lower number.