Pregnancy Calculator
Calculate your due date, track pregnancy progress, and monitor your baby's development week by week. Get accurate pregnancy information based on your last menstrual period or conception date.
Pregnancy Calculator
How to Use the Pregnancy Calculator
- Choose Calculation Method: Select between Last Menstrual Period (LMP) or Conception Date
- Enter Date: Input the first day of your last menstrual period or your conception date
- Cycle Length: If using LMP method, enter your average cycle length (typically 28 days)
- View Results: See your due date, current pregnancy week, and trimester information
- Track Progress: Monitor your baby's development and important milestones
- Plan Ahead: Use the milestone dates to prepare for important pregnancy events
Understanding Pregnancy Stages
First Trimester (1-12 weeks)
- • Heart begins beating (6 weeks)
- • Major organs form
- • Neural tube closes
- • Limbs develop
Second Trimester (13-26 weeks)
- • Gender can be determined (16+ weeks)
- • Movement felt (quickening)
- • Anatomy scan (18-22 weeks)
- • Hair and nails grow
Third Trimester (27-40+ weeks)
- • Rapid brain development
- • Lung maturation
- • Weight gain accelerates
- • Preparation for birth
Important Pregnancy Milestones
Medical Milestones
Confirm pregnancy, establish due date, initial health assessment
Nuchal translucency screening for chromosomal abnormalities
Detailed ultrasound to check baby's development
Screening for gestational diabetes
Development Milestones
Baby's heart begins beating at about 6 weeks
You may start feeling baby's movements (quickening)
Baby has a chance of survival if born prematurely
Baby is considered full-term and ready for birth
Understanding Due Date Accuracy
How Due Dates Are Calculated
- Naegele's Rule: Add 280 days (40 weeks) to the first day of your last menstrual period
- Conception Date: Add 266 days (38 weeks) to the estimated conception date
- Ultrasound Dating: Most accurate when done in first trimester
Note: Only about 5% of babies are born exactly on their due date. Most are born within 2 weeks before or after the due date.
Factors Affecting Due Date
- • Cycle Length: Longer cycles may mean later ovulation
- • First vs. Subsequent Pregnancies: First babies often arrive later
- • Multiple Pregnancies: Twins/multiples typically arrive earlier
- • Maternal Age: May influence timing slightly
- • Family History: Genetic factors can play a role
Full Term Range: 37-42 weeks is considered normal. Most healthy pregnancies last 38-42 weeks.
Frequently Asked Questions
How accurate are pregnancy due date calculators?
Due date calculators provide an estimate based on standard pregnancy length (280 days from LMP). They're most accurate when based on reliable information about your last menstrual period or conception date. However, only about 5% of babies are born exactly on their due date.
What's the difference between LMP and conception date calculations?
LMP (Last Menstrual Period) adds 280 days from the first day of your last period, while conception date adds 266 days from when conception occurred. LMP is more commonly used because it's easier to remember, but conception date can be more accurate if you know exactly when you conceived.
Can my due date change?
Yes, your due date may be adjusted based on ultrasound measurements, especially if done in the first trimester. Early ultrasounds are very accurate for dating pregnancies and may reveal that your pregnancy is further along or less advanced than initially calculated.
When should I start feeling my baby move?
First-time mothers typically feel movement between 18-25 weeks, while mothers who have been pregnant before may feel movement as early as 16 weeks. These first movements are called "quickening" and feel like flutters or bubbles.
What if my baby is overdue?
Pregnancies lasting 42 weeks or more are considered post-term. Your healthcare provider will monitor you and your baby closely and may recommend induction of labor to prevent complications. Most providers will not let pregnancies go beyond 42 weeks.
Are the baby size comparisons accurate?
The fruit and vegetable comparisons are approximate and based on average fetal development. Individual babies may be larger or smaller than these averages. These comparisons are meant to help visualize your baby's growth, but actual size can vary significantly.
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