I should know the length of pregnancy / number of weeks I am pregnant

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There are different ways to find out the length of the pregnancy. The pregnancy length can be estimated by: 2

  • Counting the number of days that have passed since the first day of the last menstrual period (LMP). It is common for people to make a note of the first day of each menstrual period on a calendar to be able check it if needed
  • A physical exam done by a nurse, midwife or doctor. An experienced professional will be able to assess the duration of pregnancy through a pelvic examination starting from around six weeks since the first day of the last menstruation.
  • An ultrasound. This is especially recommended if:

- The first day of her last menstrual period is not known and a physical exam is also inconclusive, or

- The pregnancy ocurred is shortly after an abortion or childbirth, so there was not a menstruation.

Additional information:

Pregnancies are conventionally dated in weeks, starting from the first day of the last menstrual period and not dated from the fertilization as some people might think. 18 If a woman has a regular cycle, ovulation usually occurs about 2 weeks after a woman's menstrual period starts, and fertilization usually occurs shortly after ovulation. Consequently, the pregnancy length is about 2 weeks more than the weeks passed since fertilization (the date you had sex). If you are calculating the pregnancy length based on the probable date of when you had sex and became pregnant you should add up about 2 weeks to get the approximate pregnancy length.