About

Standard obstetric dating relies on Naegele's Rule, which assumes a regular 28-day cycle. However, cycle variability can shift the Estimated Due Date (EDD) by days or weeks. This tool offers a precise calculation of gestational age and a comprehensive timeline. It maps out critical medical windows - such as the optimal time for the Nuchal Translucency scan or the Anatomy scan - and provides lifestyle context like the baby's potential Zodiac sign. This helps expectant parents plan appointments and leave with greater confidence.

Formulas

The EDD is calculated using the First Day of LMP + 280 Days (40 Weeks).

D_due = D_lmp + 280 days

Current Gestational Age is the difference between today and the LMP date.

Reference Data

Milestone	Gestational Week	Significance
Conception (Approx)	2 Weeks	Fertilization
Heartbeat Detectable	6 - 7 Weeks	Early Ultrasound
First Trimester End	13 Weeks	Risk of loss drops
Anatomy Scan	18 - 22 Weeks	Gender / Development
Viability	24 Weeks	Survival possible outside
Full Term	37 - 40 Weeks	Ready for birth

Frequently Asked Questions

Only about 5% of babies are born on their exact due date. It is an estimation. A "Full Term" pregnancy is considered anywhere from 37 to 42 weeks.

If your cycle is longer, ovulation likely occurred later, pushing the due date back. This tool adjusts the calculation: for every day over 28, add 1 day to the due date.

The second trimester technically begins at week 14, though some definitions use week 13. It is often called the "honeymoon phase" of pregnancy.

Yes. Conception usually occurs about 2 weeks after the LMP in a standard cycle. The tool provides this reverse-calculation estimate.