Pregnancy Week-by-Week Tracker

Track your pregnancy journey week by week. Learn about fetal development, maternal changes, and important milestones.

Due Date Calculator
Current Week Calculator
Manual Week Selection
Ultrasound Adjustment

Due Date Calculation: Based on Naegele's Rule: Due Date = First day of Last Menstrual Period + 280 days (40 weeks)

Note: Only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after. This is an estimate based on a 28-day cycle.

Enter the first day of your last menstrual period
Typical menstrual cycle length in days (21-45, default: 28)
If you know your conception date, enter it here for a more accurate calculation

Current Week Calculation: Enter your due date or last menstrual period to calculate your current pregnancy week.

Enter your estimated due date
Today's date (defaults to current date)

Manual Week Selection: Select a specific pregnancy week to learn about fetal development and maternal changes.

Week 20
Drag the slider to select a specific pregnancy week (1-42)

Ultrasound Adjustment: If you've had an ultrasound, you can adjust your due date based on ultrasound measurements for greater accuracy.

Date when ultrasound was performed
weeks days
Gestational age based on ultrasound measurements

Calculating your pregnancy details...

Understanding Pregnancy Trimesters

Pregnancy is typically divided into three trimesters, each lasting about 13-14 weeks. Each trimester has distinct developmental milestones and maternal changes.

Pregnancy Timeline:

  • First Trimester: Weeks 1-13 (Months 1-3) - Organ formation and early development
  • Second Trimester: Weeks 14-27 (Months 4-6) - Rapid growth and movement begins
  • Third Trimester: Weeks 28-40+ (Months 7-9) - Final preparation for birth

Medical Guidelines and References

Based on guidelines from:

  • American College of Obstetricians and Gynecologists (ACOG)
  • World Health Organization (WHO)
  • National Health Service (NHS) UK
  • American Pregnancy Association

Pregnancy Milestones Timeline

Week 4

Positive pregnancy test. Embryo implants in uterus. Neural tube begins to form.

Week 8

All major organs have begun to form. Embryo is now called a fetus.

Week 12

First trimester ends. Risk of miscarriage decreases significantly.

Week 16

Possible to determine baby's sex via ultrasound. Baby begins to hear sounds.

Week 20

Mid-pregnancy ultrasound (anatomy scan). Mother may feel baby's movements.

Week 24

Baby reaches viability - could survive outside womb with intensive care.

Week 28

Third trimester begins. Baby's eyes open. Brain development accelerates.

Week 37

Baby is considered full term. Lungs are mature. Baby may drop into pelvis.

Week 40

Due date arrives. Only 5% of babies are born on their exact due date.

Frequently Asked Questions & Medical Information

Calculation Accuracy:

  • LMP-based calculation: Accurate for women with regular 28-day cycles (within ±1 week)
  • Ultrasound-based calculation: Most accurate method, especially first trimester ultrasound (±3-5 days)
  • Conception date: Accurate if known precisely (±1 week)

Medical Note: Always use ultrasound dating when available, especially if there's discrepancy with LMP dating.

Multiple Pregnancy Considerations:

  • Twins: Average gestation is 37 weeks (vs 40 for singletons)
  • Triplets: Average gestation is 34 weeks
  • Quadruplets+: Average gestation is 32 weeks

Growth Patterns: Multiple pregnancies often show different growth curves. Regular ultrasound monitoring is essential.

Medical Recommendation: Multiple pregnancies are automatically considered high-risk and require specialized care.

High-Risk Pregnancy Indicators:

  • Advanced maternal age (35+ years)
  • Previous pregnancy complications
  • Multiple pregnancy
  • Pre-existing medical conditions (diabetes, hypertension, etc.)
  • Gestational diabetes or preeclampsia in current pregnancy
  • Abnormal ultrasound findings
  • Vaginal bleeding during pregnancy

Action Required: If you have any of these risk factors, ensure you're under close medical supervision.

Contact Your Healthcare Provider Immediately If You Experience:

  • Severe abdominal pain
  • Vaginal bleeding
  • Severe headaches or visual changes
  • Decreased fetal movement after 28 weeks
  • Fluid leaking from vagina
  • Regular contractions before 37 weeks
  • Fever over 100.4°F (38°C)

Emergency Signs: If you experience severe pain, heavy bleeding, or cannot feel baby moving (after 28 weeks), seek emergency medical care immediately.

Standard Prenatal Testing Schedule:

Time Tests/Screenings
First Visit (6-10 weeks) Blood type, CBC, STI screening, urine culture
10-13 weeks First trimester screening (nuchal translucency)
16-20 weeks Quad screen (optional), anatomy ultrasound
24-28 weeks Glucose challenge test, anemia check
35-37 weeks Group B strep test

Note: Your healthcare provider may recommend additional testing based on your specific situation.