Pregnancy Calculator
Calculate your due date, current pregnancy week, and important milestones
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Important Dates
How Pregnancy is Calculated
Pregnancy is typically calculated from the first day of your last menstrual period (LMP), not from conception. This means you're considered "2 weeks pregnant" at conception. A full-term pregnancy lasts about 40 weeks (280 days) from the LMP, or 38 weeks from conception.
Pregnancy Trimesters
First Trimester (Weeks 1-13)
Major organs and body systems develop. Morning sickness, fatigue, and breast tenderness are common. First prenatal visit typically occurs around week 8-12. First ultrasound often at 8-12 weeks.
Second Trimester (Weeks 14-27)
Often called the "honeymoon period" - energy returns, morning sickness usually subsides. You'll feel baby's first movements ("quickening") around weeks 16-25. Anatomy scan typically at 18-22 weeks reveals baby's sex and checks development.
Third Trimester (Weeks 28-40)
Baby grows rapidly. Back pain, swelling, and frequent urination common. Braxton Hicks contractions may begin. Final preparations for birth. Weekly prenatal visits begin around week 36.
Important Pregnancy Milestones
- Week 4-5: Positive pregnancy test possible
- Week 6-8: Heartbeat detectable on ultrasound
- Week 10-13: First trimester screening, nuchal translucency scan
- Week 18-22: Anatomy scan (morphology ultrasound)
- Week 24-28: Glucose tolerance test for gestational diabetes
- Week 35-37: Group B strep test
- Week 37: Considered full term, baby could arrive anytime
- Week 39-40: Optimal time for delivery
Due Date Accuracy
Only about 5% of babies arrive exactly on their due date. Most babies arrive within 2 weeks before or after the due date. First-time mothers often deliver slightly past their due date, while those who've had children before may deliver earlier. Ultrasound measurements in the first trimester can help refine your due date.
Signs of Labor
- Regular contractions: Every 5-10 minutes lasting 30-70 seconds
- Water breaking: Gush or trickle of amniotic fluid
- Bloody show: Pink or bloody mucus discharge
- Lower back pain: Constant, intense lower back pain
- Diarrhea: Body's natural way of clearing the system
When to Call Your Doctor
Contact your healthcare provider immediately if you experience:
- Severe abdominal pain or cramping
- Heavy vaginal bleeding
- Severe headache or vision changes
- Sudden swelling of hands, face, or feet
- Decreased fetal movement
- Signs of preterm labor before 37 weeks
- Fever over 100.4°F (38°C)
Prenatal Care Schedule
- Weeks 4-28: Visit every 4 weeks
- Weeks 28-36: Visit every 2 weeks
- Weeks 36-40: Visit every week
Healthy Pregnancy Tips
- Take prenatal vitamins: Start with 400-800 mcg folic acid daily before conception if possible
- Eat a balanced diet: Focus on fruits, vegetables, whole grains, lean protein, and healthy fats
- Stay hydrated: Drink 8-12 glasses of water daily
- Exercise regularly: 30 minutes of moderate exercise most days (if approved by doctor)
- Get enough rest: Sleep 7-9 hours nightly, nap when tired
- Avoid harmful substances: No alcohol, smoking, or recreational drugs
- Limit caffeine: Under 200mg daily (about one 12 oz coffee)
Frequently Asked Questions
How accurate is my due date?
Due dates are estimates. Only 5% of babies arrive on the exact date. Your doctor may adjust the due date based on first-trimester ultrasound measurements, which are accurate to within 3-5 days.
Can I find out baby's sex?
Baby's sex can typically be determined via ultrasound around 18-22 weeks. Non-invasive prenatal testing (NIPT) blood tests can reveal sex as early as 10 weeks with high accuracy.
What if I don't know my LMP?
Your doctor can estimate gestational age through ultrasound measurements. First-trimester ultrasounds are most accurate for dating pregnancies.
How much weight should I gain?
Recommendations based on pre-pregnancy BMI: Underweight (BMI <18.5): 28-40 lbs, Normal weight (BMI 18.5-24.9): 25-35 lbs, Overweight (BMI 25-29.9): 15-25 lbs, Obese (BMI ≥30): 11-20 lbs.