Medical & Pharmaceutical
Pregnancy Calculator
Calculate your estimated due date and track important pregnancy milestones based on your last menstrual period or conception date.
Enter your last menstrual period or conception date to calculate pregnancy details
Related to Pregnancy Calculator
The pregnancy calculator uses established medical guidelines to estimate your due date and track important pregnancy milestones. The calculation can be based on either your last menstrual period (LMP) or known conception date, using two different methods:
LMP Method
When using the last menstrual period (LMP), the calculator adds 280 days (40 weeks) to your LMP date. This is the most common method used by healthcare providers, as the exact conception date is often unknown. The first day of your last period is considered week 1 of pregnancy, even though conception typically occurs around week 2.
Conception Date Method
If you know your conception date (from IVF or ovulation tracking), the calculator adds 266 days (38 weeks) to this date. This method provides a more accurate estimate but requires knowing the exact date of conception.
The calculator provides several key pieces of information to help you understand your pregnancy timeline:
Due Date
Your estimated due date (EDD) is when your baby is expected to be born. Only about 5% of babies are born on their exact due date, with most births occurring within two weeks before or after this date. The due date is a guideline for monitoring your pregnancy's progress.
Pregnancy Week
Your current week of pregnancy helps track fetal development and maternal changes. The pregnancy is divided into three trimesters: First (weeks 1-13), Second (weeks 14-26), and Third (weeks 27-40). Each trimester brings different developmental milestones and pregnancy symptoms.
Conception Date
The estimated conception date is when fertilization likely occurred. If using the LMP method, this is calculated as approximately 14 days after your last period, though actual conception timing can vary based on your ovulation cycle.
1. How accurate is the pregnancy calculator?
The pregnancy calculator provides an estimate based on standard pregnancy duration. The accuracy depends on the input method used (LMP or conception date) and the regularity of your menstrual cycle. The conception date method tends to be more accurate when the exact date is known.
2. Why does pregnancy count start from the last period?
Pregnancy is traditionally counted from the first day of the last menstrual period (LMP) because it provides a clear, identifiable date and is more reliable than trying to determine the exact conception date. This method adds approximately two weeks before conception actually occurs.
3. What factors can affect my due date?
Several factors can affect your actual due date, including irregular menstrual cycles, variations in ovulation timing, maternal age, previous pregnancies, and genetic factors. The calculated due date should be considered an estimate and may be adjusted based on ultrasound measurements.
4. When should I schedule my first prenatal visit?
Most healthcare providers recommend scheduling your first prenatal visit as soon as you know you're pregnant, typically between weeks 6-8 of pregnancy. However, if you have any health concerns or high-risk factors, you should contact your healthcare provider immediately.
5. What is the scientific source for this calculator?
This calculator follows the standard gestational age calculation method endorsed by the American College of Obstetricians and Gynecologists (ACOG) and the World Health Organization (WHO). The calculations are based on Naegele's rule, a standard method for estimating delivery date that has been validated through extensive research. The formula accounts for an average pregnancy duration of 280 days (40 weeks) from the last menstrual period, or 266 days (38 weeks) from conception. This methodology is supported by numerous peer-reviewed studies in obstetric medicine and is consistently used in clinical practice worldwide.