Gestational Calculator: weeks, months (and important dates)

The gestational age calculator is a simple way to find out the number of days, weeks or months that have passed since the start of pregnancy. Knowing the gestational age allows you to understand what stage of development the baby is at, but it also helps to calculate the likely date of delivery, which, as a rule, takes place 40 weeks after the start of pregnancy.

To find out your gestational age, please enter the date of the first day of your last menstrual period into the calculator:

How is gestational age calculated?

Gestational age is calculated from the date of the last menstruation, simply counting how many days, weeks or months there are between the last menstruation and the current date.

According to gestational age, it is also possible to know which trimester of pregnancy the woman is in:

• First trimester: corresponds to the period up to the third month and up to the middle of week 13;
• Second trimester: corresponds to the period up to the sixth month and goes from the middle of week 13 to week 27;
• Third quarter: corresponds to the period up to the ninth month and goes from week 28 to week 42.

Knowing the gestational age is interesting to know how the baby is developing and whether vision and hearing are already developing, for example. Learn more about your baby’s development each week.

What if I don’t know the date of my last period?

Although the calculation of gestational age takes into account the date of the last menstrual period, it is also possible to find out through laboratory and imaging tests.

Therefore, when a woman does not know the last day she had her period, the obstetrician may recommend carrying out a beta HCG test, which checks the concentration of this hormone in the blood, which varies as the pregnancy develops. See how to understand the results of the beta HCG test.

In addition to the beta HCG exam, the doctor can also indicate the gestational age through an ultrasound exam, in which the baby’s developmental growth is observed, in addition to being able to check the height of the uterus, with these exams being carried out during the consultation. prenatal.

How to know the baby’s date of birth?

In addition to the concentration of beta HCG in the blood and carrying out an ultrasound to check the baby’s growth pattern, the likely date of delivery can be checked through a calculation that takes into account the date of the last menstrual period. Therefore, to know the possible date of delivery, it is recommended to count 7 days after menstruation and 9 months after the month of the last menstruation.

In other words, if the last menstruation took place on January 14th, the baby’s likely birth date is between October 20th and 21st. However, this calculation considers that the baby will be born in week 40, but the baby is ready from week 37 and can be born until week 42.

Check out more information on how to know your expected due date.