Pregnancy Calculator - Due Date & Gestational Age Calculator
Calculate your pregnancy timeline using multiple dating methods including LMP, due date, ultrasound, conception date, and IVF transfer date. Get accurate gestational age, due date, and pregnancy milestones with medical precision.
Pregnancy Dating Methods
First day of your last menstrual period
Pregnancy Timeline
Enter pregnancy information to calculate your timeline
What is Pregnancy Calculator - Due Date & Gestational Age Calculator?
A pregnancy calculator helps determine important dates in your pregnancy journey using various dating methods. Accurate pregnancy dating is crucial for proper prenatal care, monitoring fetal development, and planning delivery. Our calculator follows established medical guidelines and provides estimates that align with standard obstetric practice.
Pregnancy Dating Methods
Last Menstrual Period (LMP)
The most common method using Naegele's rule: due date = LMP + 280 days. Assumes a 28-day cycle with ovulation on day 14. This method is used by most healthcare providers as the standard for pregnancy dating.
Ultrasound Dating
Uses measurements from ultrasound scans to determine gestational age. Most accurate when performed in the first trimester (6-13 weeks). Crown-rump length (CRL) measurements provide the most precise dating.
IVF Dating
For IVF pregnancies, conception date is known precisely. Accounts for embryo development stage at transfer. Day 3 and Day 5 (blastocyst) transfers require different calculations for accurate dating.
Conception Dating
When the conception date is known or estimated, typically used to calculate gestational age by adding 14 days to account for the pre-ovulation period included in medical dating.
Gestational Age vs Fetal Age
Gestational age is calculated from the LMP and is typically 2 weeks longer than fetal age (actual age since conception). Medical professionals use gestational age for standardized care and monitoring because it provides a consistent reference point regardless of variations in ovulation timing or conception date certainty.
Pregnancy Trimesters
- First Trimester: Weeks 1-13 (organ development, highest miscarriage risk, morning sickness common)
- Second Trimester: Weeks 14-27 (anatomy scan, movement begins, energy often returns)
- Third Trimester: Weeks 28-40+ (rapid growth, preparation for birth, increased monitoring)
Delivery Window and Term Classifications
- Early Term: 37-38 weeks (baby is mature but may benefit from additional development)
- Full Term: 39-40 weeks (optimal time for delivery)
- Late Term: 41 weeks (monitoring increases)
- Post Term: 42+ weeks (induction typically recommended)
Medical Accuracy and Limitations
Pregnancy calculations provide estimates based on population averages and standard formulas. Individual pregnancies may vary due to factors such as irregular menstrual cycles, delayed ovulation, or individual fetal growth patterns. Regular prenatal care with serial ultrasound examinations provides the most accurate assessment of pregnancy progress and fetal development.
Important Medical Disclaimer
This calculator is for educational and informational purposes only. It does not constitute medical advice and should not be used as a substitute for professional medical consultation, diagnosis, or treatment. Always consult with qualified healthcare providers for medical advice, pregnancy monitoring, and prenatal care decisions. Pregnancy dating and management should always be supervised by medical professionals.