Pregnancy Due Date Calculator
Calculate your baby's due date with precision using multiple methods
Track your pregnancy journey with weekly milestones, trimester information, and personalized development insights for you and your baby.
Due Date Calculator
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Estimated Due Date
Current Status
Important Dates
Enter your information above to calculate your due date and track your pregnancy journey.
Understanding Pregnancy Due Dates
Comprehensive guide to pregnancy calculations, milestones, and what to expect during your journey
How Due Date Calculation Works
Pregnancy due date calculation is based on a 280-day gestation period from the last menstrual period (LMP). This method, known as Naegele's Rule, adds 280 days to the first day of your last menstrual period. The calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. However, only about 5% of babies are born on their exact due date, with most births occurring within two weeks before or after the estimated date.
Our calculator offers multiple methods for increased accuracy. The LMP method is most common and works well for women with regular cycles. The conception date method is more precise if you know exactly when conception occurred, while ultrasound-based calculations provide the most accurate results, especially when performed in the first trimester.
Different Calculation Methods
Last Menstrual Period (LMP)
The most commonly used method, adding 280 days to the first day of your last period. This method works best for women with regular 28-day cycles.
Conception Date
More accurate if you know the exact conception date. Adds 266 days to the conception date, accounting for the actual fertilization timing.
Ultrasound Dating
The most accurate method, especially when performed between 8-18 weeks. Measures fetal development to determine gestational age.
Pregnancy Milestones Timeline
Week 4
Missed period, home pregnancy test
Week 8
First prenatal appointment
Week 12
End of first trimester
Week 20
Anatomy scan, gender reveal
Factors Affecting Due Date Accuracy
Several factors can influence the accuracy of due date calculations. Irregular menstrual cycles, late ovulation, or uncertain LMP dates can affect traditional calculations. First-time mothers tend to deliver slightly later than experienced mothers, while multiple pregnancies (twins, triplets) typically result in earlier deliveries. Maternal age, health conditions, and genetic factors also play roles in determining actual delivery timing.
Prenatal Care Schedule
Regular prenatal care is essential for monitoring both maternal and fetal health throughout pregnancy. The recommended schedule typically includes monthly visits during the first and second trimesters, bi-weekly visits during weeks 28-36, and weekly visits from week 36 until delivery. Each visit includes weight monitoring, blood pressure checks, urine tests, and fetal heart rate monitoring.
Key Prenatal Tests
- • Blood type and Rh factor (First visit)
- • Glucose screening (24-28 weeks)
- • Group B strep test (35-37 weeks)
- • Anatomy ultrasound (18-22 weeks)
- • Genetic screening (10-13 weeks)
Nutrition During Pregnancy
Proper nutrition is crucial for fetal development and maternal health. A balanced diet should include increased protein, calcium, iron, and folic acid. Prenatal vitamins help fill nutritional gaps, but shouldn't replace a healthy diet. Avoid alcohol, raw fish, unpasteurized dairy, and high-mercury fish. Stay hydrated and maintain appropriate weight gain based on pre-pregnancy BMI.
Essential Nutrients
- • Folic acid (400-800mcg)
- • Iron (27mg daily)
- • Calcium (1000mg daily)
- • DHA (200mg daily)
Foods to Avoid
- • Raw or undercooked meat
- • High-mercury fish
- • Unpasteurized products
- • Alcohol and tobacco
Frequently Asked Questions
How accurate are due date calculators?
Due date calculators provide estimates based on established medical formulas, but they're not 100% accurate. Only about 5% of babies are born on their exact due date. Most babies (about 80%) are born within two weeks before or after the estimated due date. The accuracy depends on factors like regular menstrual cycles, accurate LMP dates, and individual variations in pregnancy length.
What if I have irregular periods?
If you have irregular periods, the LMP method may be less accurate. In such cases, ultrasound dating is preferred, especially when performed in the first trimester. If you know your conception date or ovulation date, these methods can provide more accurate results. Consult with your healthcare provider for the most appropriate calculation method for your situation.
Can my due date change during pregnancy?
Yes, your due date may be adjusted based on ultrasound measurements, especially if performed early in pregnancy. First-trimester ultrasounds are most accurate for dating. If there's a significant discrepancy between your LMP-based due date and ultrasound measurements, your healthcare provider may revise the estimated due date. However, due dates are rarely changed after 20 weeks of pregnancy.
What happens if I go past my due date?
Going past your due date is common and usually not cause for concern. Pregnancies can safely continue until 42 weeks. However, your healthcare provider will monitor you more closely after 40 weeks, checking fetal movement, amniotic fluid levels, and placental function. Induction may be discussed if you reach 41-42 weeks, depending on your individual circumstances and risk factors.
How do multiple pregnancies affect due dates?
Multiple pregnancies (twins, triplets) typically have shorter gestation periods. Twin pregnancies average 37 weeks, while triplets average 33 weeks. Our calculator adjusts for multiple pregnancies, but individual monitoring by your healthcare provider is essential. Multiple pregnancies require more frequent prenatal visits and specialized care due to increased risks and earlier delivery likelihood.