Home
Back
Pregnancy Calculation Formula:
| From: | To: |
This calculator determines the optimal time to take a pregnancy test and estimates your due date based on your last menstrual period (LMP). It combines test timing guidance with pregnancy dating for comprehensive pregnancy planning.
The calculator uses standard pregnancy calculation formulas:
Where:
Explanation: Pregnancy tests become reliable approximately 3 weeks after LMP when hCG levels are detectable. The due date is calculated using Naegele's rule (280 days from LMP).
Details: Accurate pregnancy dating is essential for proper prenatal care, monitoring fetal development, scheduling important tests, and preparing for delivery. Knowing when to test helps avoid false negative results.
Tips: Enter the first day of your last menstrual period accurately. Use a calendar to ensure correct date entry. Remember that these are estimates and individual variations may occur.
Q1: Why wait 21 days after LMP to test?
A: This allows time for ovulation, fertilization, implantation, and sufficient hCG buildup for detection by home pregnancy tests.
Q2: How accurate is the due date calculation?
A: The due date is an estimate - only about 5% of women deliver on their exact due date. Most deliver within 2 weeks before or after.
Q3: What if my cycles are irregular?
A: This calculator assumes a 28-day cycle. If your cycles are irregular, consult your healthcare provider for more accurate dating, possibly using ultrasound.
Q4: Can I test earlier than 21 days?
A: Early detection tests may work 10-14 days after conception, but testing too early can give false negatives. Waiting until 21 days after LMP increases accuracy.
Q5: What factors can affect these calculations?
A: Irregular cycles, recent hormonal contraception use, breastfeeding, and medical conditions affecting ovulation can impact accuracy.