Enter your due date or LMP to see exactly how many weeks and days you have left, plus weekly development milestones, labor signs to watch for, and a day-by-day countdown to your due date.
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What to expect
Your countdown starts at 40 weeks (280 days) from your last menstrual period. The due date marks the midpoint of your “full term” window—most babies arrive between 37 and 42 weeks, though exactly on your due date happens for only about 1 in 20. Use this calculator to track key milestones, fetal development stages, and prepare for the signs that labor is approaching.
As your pregnancy progresses, your baby is growing rapidly and developing critical systems. Here’s a week-by-week snapshot of the major milestones ahead:
Infographic
Weeks of Pregnancy: Development Timeline
Major fetal milestones from weeks 4 through delivery
Fetal Development Progression
Weeks 4–8: Embryonic period
Weeks 9–20: Rapid growth & organ development
Weeks 21–28: Viability milestone & brain development
Weeks 29–36: Continued growth & positioning
Weeks 37–42: Full term & labor readiness
Weeks 4–8
Heart begins beating, neural tube forms, brain and spinal cord development begins. Baby is about the size of a blueberry.
Weeks 9–20
All major organs are forming. Facial features become distinct, fingers and toes appear. Quickening (fetal movement) may be felt around week 16–20.
Weeks 21–28
Baby is viable (able to survive outside the womb with medical support). Rapid brain development and weight gain accelerate. Eyes open around week 26–27.
Weeks 29–36
Continued rapid growth. Baby practices breathing movements. Lungs continue maturing. Baby begins moving into head-down position for birth.
Weeks 37–38
Early term. Baby is fully formed. Immune system antibodies transferred from mother. Growth slows as baby prepares for birth.
Weeks 39–42
Full term. Baby is about 7–8 lbs, 19–21 inches. All systems ready. Labor can begin anytime. Induction typically offered by week 42.
Signs Labor Is Approaching
In the weeks before your due date, watch for these signs that your body is preparing for labor. Not all will occur, and not all need to happen at once:
🔽
Lightening
Baby drops into the pelvis; you can breathe easier but pressure increases on bladder.
💧
Show
Mucus plug releases; pinkish or bloody discharge may appear.
🌊
Rupture of Membranes
Amniotic fluid leaks or gushes; contact your provider immediately.
💪
Contractions
Regular, rhythmic tightening of the uterus. True labor contractions increase in frequency and intensity.
🎯
Cervical Effacement
Cervix thins and softens (detected during cervical exam by provider).
📊
Dilation
Cervix begins to open from 0 to 10 cm (verified by provider).
When to call your provider: Contact your maternity team immediately if you experience rupture of membranes, active vaginal bleeding, severe abdominal pain, or any concerning symptoms. Don’t wait—always err on the side of caution.
Getting Ready: Trimester-by-Trimester Checklist
Use your countdown to stay on track with essential preparations:
Install and test your car seat, pre-register at your hospital, finalize your birth plan, pack your hospital bag.
✓
By Weeks 37–40 (Full Term)
Review labor signs and when to call. Arrange leave coverage. Stay within 30 minutes of your hospital. Rest and prepare mentally.
Frequently Asked Questions
LMP (last menstrual period) dating counts 280 days from the first day of your period. Due-date dating uses a calculated date that may be adjusted based on ultrasound confirmation. If your LMP is known and regular, both methods usually align. The calculator adjusts for cycle length automatically.
Your due date may shift slightly if an early ultrasound (weeks 8–13) differs from your LMP calculation by more than 5–7 days. Once set, ACOG guidance recommends keeping the date fixed for the rest of pregnancy. Later ultrasounds monitor growth, not dating.
Reaching your due date is normal—about 1 in 5 babies arrive before, and a similar share arrive after. Your provider will likely schedule additional monitoring (non-stress tests, amniotic fluid checks) and discuss induction options if you haven’t delivered by week 41.
If your cycle is irregular or unknown, your due date should be based on a first-trimester ultrasound (weeks 8–13) rather than LMP alone. Always use the date your doctor or midwife confirms, as they have access to your full medical history and imaging.
Yes. The countdown counts all days (weekends, holidays, etc.) from today until your due date, giving you the most accurate picture of time remaining. Your provider’s office will also be counting the same way.
Twin pregnancies typically deliver around week 37–38 (not week 40), as the risk of complications rises sooner with multiple babies. Your doctor will give you a specific due date for your situation. Use this calculator as a general reference, but follow your provider’s guidance.
Dr. Khan reviews all pregnancy, labor, and fetal development content on PregCalc.com for clinical accuracy against current ACOG, NHS, and CDC guidance. View full credentials →
Last updated: June 2026·Evidence-based: ACOG, NHS, CDC, Mayo Clinic·Reviewed quarterly
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Your due date has passed. If you have not delivered, contact your healthcare provider immediately for monitoring and next steps.
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Today is your due date! Labor can begin anytime. Watch for labor signs and stay in contact with your provider.
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You are in your final week! Watch for labor signs: contractions, show, rupture of membranes. Have your bag ready and know when to call your provider.
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Labor could start anytime now. Make sure you know the signs of labor and when to contact your provider. Keep your hospital bag accessible.
You are in the preterm period. If you experience signs of preterm labor (regular contractions, bleeding, fluid leakage, severe pain), contact your provider immediately.
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Our pregnancy countdown calculator uses your due date to show exactly how many days, weeks, and trimesters remain, helping you plan ahead with confidence. For more on how due dates are estimated, see the ACOG guide on pregnancy dating, or pair this tool with our Due Date Calculator for a full timeline of your pregnancy.
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