Pregnancy & Period Tracker

What this tool does

This tool provides educational pregnancy dating and menstrual cycle calendar estimates from the first day of your last menstrual period (LMP).

What inputs are required

• LMP date (YYYY-MM-DD).
• Optional average cycle length (21–45 days) for cycle mode.

How the result is calculated

• Estimated due date = LMP + 280 days (Naegele).
• Gestational age = days from LMP to the reference date.
• Ovulation ≈ LMP + (cycle length − 14); fertile window spans ovulation − 5 through + 1 day.

What the result means

• Dates are planning estimates only.
• Ultrasound and clinical assessment override calendar math.

Important limitations

• Assumes typical adult cycles; irregular cycles need clinical guidance.
• Not a contraception or fertility-treatment tool.

When professional guidance may be useful

• Discuss pregnancy dating and cycle concerns with a qualified clinician.
• Use Find a healthcare professional in the DoseFirst directory when you need in-person support.