Positive test: first steps
When to book and when not to wait.
Open informationPrivate estimation tool
How many weeks pregnant am I?
Enter the first day of your last menstrual period. The calculator estimates gestational age and due date using a 280-day calculation.
- Obstetric consultation
- Advanced ultrasound
- Laboratory and screening
- Late-pregnancy monitoring
- Nutrition
Complementary follow-upAskabide + Osakidetza · birth at the reference hospital
Calculator
This is an estimate. It does not replace ultrasound dating or clinical assessment.
How to interpret the result
Obstetric weeks are counted from the first day of the last menstrual period, not the day of fertilisation. The first two calculated weeks therefore usually precede conception.
If cycles are irregular, the date is uncertain, bleeding has occurred or ultrasound shows a relevant difference, dating should be reviewed clinically.
- The date entered is not stored or transmitted.
- The estimated due date is not an exact birth date.
- First-trimester ultrasound may adjust dating.
What commonly comes next
First ultrasound
What may be visible at the estimated stage.
Open information
Complete follow-up
See the clinical timeline.
Open informationClinical sources
General information only. It does not replace an individual medical assessment or recommendation.
Reviewed 19 August 2026