I got pregnant:

When does pregnancy start?

Although it may seem strange, the beginning of pregnancy is counted from the first day of the last period. At the same time, fertilization of the egg and its implantation on the uterine lining takes place up to 2 or 3 weeks from the first day of the cycle. So why does a woman refer to herself as pregnant even before intercourse? This is because the first day of the menstrual cycle is the beginning of a woman's reproductive cycle. In the first two weeks, one egg matures, which can then be fertilized.

What does the medical designation of the week of pregnancy mean?

In order for doctors to quickly orientate themselves in the stage of pregnancy, they devised a uniform description of the week of pregnancy, e.g. 15+3. The first number indicates the number of completed weeks of pregnancy and the second the number of days beyond the completed weeks. In the case of the designation 15+3, the 15th week of pregnancy has ended and 3 days have passed.

Calculation of the week of pregnancy and calculation of the due date

Pregnancy lasts an average of 280 days, i.e. 9 calendar months, or 40 weeks.

We further divide pregnancy into 3 trimesters:

  • 1st trimester from conception to 12+6 (i.e. before the end of the 13th week of pregnancy)
  • 2nd trimester from 13+0 to 27+6 (i.e. before the end of the 28th week of pregnancy)
  • 3rd trimester from 28+0 until delivery

When calculating the week of pregnancy, we are usually guided by the day of the last menstrual period. The expected date will be confirmed by the doctor only during the ultrasound at the first trimester screening. However, this is still an estimated date of birth, which is only indicative. In most cases, the birth occurs within a range of up to 2 weeks before the expected date of birth and 2 weeks after it (ie from 38+0 to 42+0).

There are also other methods of calculating the stage of pregnancy or the due date, such as the day of conception or the day of the baby's first movements. However, these methods are not very accurate.

A very quick and effective method for calculating the due date using the last day of menstruation is Naegele's rule. The rule works as follows:

Add 7 days to the date of the last period and subtract 3 months = the result is the approximate date of birth (the year must be adjusted).

What can I expect during pregnancy?

If you don't know if your symptoms during pregnancy are normal and you are keen to know what to expect you can use our pregnancy calculator, which will guide you step by step through the course of your pregnancy.

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