🤰 Advanced Pregnancy Calculator

Calculate your estimated due date using multiple methods: LMP, conception date, ultrasound dating, or IVF transfer. Get personalized pregnancy timeline and WHO-approved recommendations.

📋 Select Calculation Method:

📅 Date of Last Menstrual Period (LMP):

🔄 Average Cycle Length (days):

📅 Known Due Date:

📅 Ultrasound Date:

📏 Gestational Age at Ultrasound (weeks):

➕ Additional Days:

📅 Conception Date:

📅 IVF Transfer Date:

🥚 Embryo Age at Transfer (days):

⚠️ Medical Disclaimer

This calculator provides estimates based on standard obstetric formulas and should not replace personalized medical advice from healthcare professionals. Due dates are estimates, and only about 5% of babies are born on their exact due date. Always follow the guidance of your healthcare provider for pregnancy dating and management.

📚 Understanding Pregnancy Dating Methods

Pregnancy dating can be calculated using several methods, each with different levels of accuracy. The most common approach is Naegele's Rule, which estimates delivery at 40 weeks from the first day of the last menstrual period (LMP).

Last Menstrual Period (LMP) Method

This is the most commonly used method for estimating due dates:

Assumes a 28-day menstrual cycle with ovulation on day 14
Pregnancy is calculated as 40 weeks from the first day of LMP
Actual conception typically occurs about 2 weeks after LMP
Adjustments can be made for longer or shorter menstrual cycles

Ultrasound Dating

Ultrasound provides the most accurate dating, especially in early pregnancy:

First-trimester ultrasounds (6-13 weeks) can predict due dates within ±5-7 days
Crown-rump length (CRL) measurement is most accurate early indicator
Second-trimester dating becomes less precise (±2-3 weeks)
Healthcare providers may adjust due dates based on early ultrasound findings

IVF and Assisted Reproduction Dating

IVF pregnancies have the most precise dating available:

Egg retrieval date is considered day 14 of the menstrual cycle
Due date is calculated as 40 weeks from retrieval date minus embryo age
For frozen embryo transfers, the calculation is based on transfer date and embryo development stage
This method typically provides the most accurate due date estimation

WHO Recommendations for Pregnancy Dating

The World Health Organization recommends:

Using the first day of the last menstrual period for initial dating
Confirming with first-trimester ultrasound when available
Adjusting the due date if ultrasound dating before 14 weeks differs by more than 7 days from LMP dating
Using ultrasound dating if LMP is uncertain or cycles are irregular
Establishing an accurate due date early in pregnancy for appropriate prenatal care timing

📊 Your Pregnancy Results

Estimated Due Date

Current Gestational Age

Trimester

Days Remaining

📅 Pregnancy Timeline

First Trimester (Weeks 1-13): Early development, organ formation, and highest risk of miscarriage. Most women experience morning sickness and fatigue.

Second Trimester (Weeks 14-27): Often called the "honeymoon period" with reduced nausea and increased energy. Baby's movements become noticeable.

Third Trimester (Weeks 28-40+): Rapid growth, final development, and preparation for delivery. Common discomforts include heartburn, back pain, and frequent urination.

❤️ Medical Recommendations

🍏 Prenatal Nutrition: Take 400-800 mcg of folic acid daily, increase iron-rich foods, ensure adequate calcium intake, and consume sufficient protein. WHO recommends a balanced diet with plenty of fruits, vegetables, and whole grains.

💊 Supplement Guidance: FDA-approved prenatal vitamins with iron, folic acid, vitamin D, and omega-3 fatty acids are recommended. Some women may need additional supplements based on individual health needs.

🏃‍♀️ Exercise: Moderate exercise is generally safe and beneficial during pregnancy. Walking, swimming, and prenatal yoga are excellent choices. Avoid activities with high fall risk or contact sports.

🚭 Lifestyle Factors: Avoid alcohol, tobacco, and recreational drugs. Limit caffeine to 200mg daily. Maintain a healthy weight gain as recommended by your healthcare provider.

🩺 Prenatal Care: Schedule regular prenatal appointments. Follow recommended screening schedules. Discuss any concerns with your healthcare provider promptly.

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❓ Frequently Asked Questions

What is the most accurate way to calculate my due date? +

The most accurate due date calculation combines multiple methods: Last Menstrual Period (LMP) dating for initial estimation, early ultrasound dating (especially between 8-13 weeks) for confirmation, and any known conception or IVF transfer dates. First-trimester ultrasounds can predict due dates with an accuracy of ±5-7 days.

Why is my due date different from my ultrasound? +

Due dates may differ between LMP calculation and ultrasound because of variations in ovulation timing, cycle length, or embryo development. Healthcare providers typically use the ultrasound date if it differs from LMP by more than 5-7 days in the first trimester, as early ultrasounds are generally more accurate for dating pregnancies.

How does IVF affect due date calculation? +

IVF pregnancies have more precise dating because the conception date is known exactly. For IVF, the due date is calculated as 38 weeks from egg retrieval or 40 weeks from the theoretical last menstrual period date. Embryo age at transfer (3-day vs. 5-day) is factored into the calculation for maximum accuracy.

Can my due date change during pregnancy? +

Yes, due dates can be adjusted, especially after first-trimester ultrasounds. If ultrasound measurements in the first trimester differ significantly from the LMP-based due date (typically more than 5-7 days), healthcare providers may change the official due date. After 20 weeks, due dates are rarely changed as fetal size becomes more variable.

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