Calculator Uni

Pregnancy Calculator

Track pregnancy milestones week by week from your due date.

Key date
Pick the first day of your last menstrual period.

How pregnancy is dated

Clinicians count from the last menstrual period (LMP), not conception — so 'week 4' is only about two weeks after fertilization. Full term runs 39–40 weeks; a first-trimester ultrasound often refines the date by a few days and takes precedence over the LMP estimate.

Trimester landmarks

The first trimester (to 13 weeks) covers organ formation and most morning sickness; the second (to 27 weeks) usually brings energy back and the anatomy scan around week 20; the third is growth and lung maturation. Only ~4% of babies arrive exactly on their due date.

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