Pregnancy Screening Schedule by Gestational Age

Enter GA, LMP, or EDD to see personalized date windows for NT, NIPT, the anatomy scan, gestational diabetes screening, and Tdap.

Reference date (today or visit date)
We calculate your schedule relative to this date.
How do you want to enter progress?
Weeks
Days (0–6)
—
NT scan:
Typical: 11w0d–13w6d
NIPT blood test:
Typical: from 10w0d
Anatomy scan:
Typical: 18–22 weeks
GDM screening:
Typical: 24–28 weeks
Tdap vaccine:
Typical: 27–36 weeks
Your EDD:
Based on your input
Windows vary by clinic and clinical context. Use with a clinician.

What this tool calculates

  • Calendar-date windows for common pregnancy tests/interventions (NT ultrasound, cfDNA/NIPT, anatomy scan, gestational diabetes screening, and Tdap vaccination) based on your gestational age or dates (LMP/EDD).
  • A one-line summary you can copy for scheduling discussions.

Dating logic

  • Gestational age (GA) is counted from the first day of the last menstrual period (LMP); estimated due date (EDD) is LMP + 280 days. If you enter GA, we infer LMP = reference date − GA.
  • All windows are computed as day ranges from LMP and then converted to calendar dates for the reference date you select (today by default).

Windows used in this calculator

  • Nuchal translucency (NT) scan: 11w0d – 13w6d.
  • cfDNA / NIPT blood test: from 10w0d (available thereafter; some services prefer ≥10+0).
  • Anatomy (mid-trimester) scan: 18–22 weeks.
  • Gestational diabetes mellitus (GDM) screening: 24–28 weeks.
  • Tdap vaccination: 27–36 weeks.

Scope and limits

  • Local protocols vary (e.g., alternate aneuploidy screening pathways, early GDM in higher-risk patients, or different Tdap timing with cocooning strategies). Follow your clinician and local guidance.
  • When an early accurate ultrasound EDD is available, use that as the anchor for scheduling.

Sources

  • ACOG — Prenatal genetic screening tests (cfDNA/NIPT from 10 weeks). acog.org
  • ACOG — Gestational diabetes (screening typically 24–28 weeks). acog.org

    • Last updated: 6 Oct 2025

Start here
Not sure of your exact GA today?

Confirm weeks+days first, then generate precise screening windows.

Open Gestational Age Calculator →

How to use this calculator

  1. Choose input mode: GA (w+d), LMP date, or EDD.
  2. Set the reference date: today or an upcoming visit.
  3. Tap “Find windows”: see exact date ranges for NT, NIPT, anatomy, GDM, and Tdap.
  4. Copy the summary to share or paste into your notes.

Tip: If GA is uncertain, confirm it with the Gestational Age or Ultrasound Due Date calculators before scheduling.