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Pregnancy Due Date Calculator

Calculate delivery date and pregnancy milestones

First day of last menstrual period
Average cycle length 28 days
days

How is Pregnancy Due Date Calculated?

The most common method is Naegele's Rule โ€” add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a standard 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, the calculator adjusts accordingly.

It is worth knowing that only about 4% of babies are actually born on their exact due date. Most babies arrive within 2 weeks before or after โ€” anywhere between 38 and 42 weeks is considered a normal full-term delivery. The due date is really an estimated date, not a deadline.

Due Date = LMP + 280 days (adjusted for cycle length)
Conception Method: Due Date = Conception Date + 266 days

The Three Trimesters of Pregnancy

First Trimester (Weeks 1-12) โ€” This is when most of the critical development happens. The baby's heart, brain, spinal cord and major organs form in these early weeks. Morning sickness, fatigue and breast tenderness are common. The risk of miscarriage is highest in this trimester, which is why many couples wait until week 12 to share the news.

Second Trimester (Weeks 13-26) โ€” Often called the "honeymoon trimester." Morning sickness typically eases, energy returns, and the pregnancy becomes visible. Around week 18-20, you will have the anatomy scan ultrasound. You will likely feel the baby move for the first time around weeks 16-25.

Third Trimester (Weeks 27-40) โ€” The final stretch. The baby gains significant weight and the body prepares for birth. Sleep becomes difficult, frequent urination returns, and Braxton Hicks contractions may begin. This is when you finalize your birth plan and hospital bag.

Important Pregnancy Milestones

Week 6-8: First heartbeat detectable by ultrasound. Week 12: First trimester screening. Week 16-20: Feel baby's first movements. Week 18-20: Anatomy scan โ€” gender can usually be determined. Week 24: Baby is considered viable if born prematurely. Week 28: Third trimester begins. Week 36: Baby is considered early term. Week 37-42: Full term delivery expected.

Antenatal Care Schedule in India

The Government of India recommends a minimum of 4 antenatal visits during pregnancy. Most obstetricians recommend monthly visits until week 28, fortnightly until week 36, then weekly until delivery. Key tests include blood group and Rh factor, hemoglobin, blood sugar, urine analysis, HIV, hepatitis B, thyroid function, and at least 2-3 ultrasounds.

Iron and folic acid supplementation is strongly recommended throughout pregnancy. Folic acid ideally should be started 3 months before conception to prevent neural tube defects.

How accurate is LMP-based due date calculation?
LMP-based calculation assumes a regular 28-day cycle and ovulation on day 14. For women with irregular cycles, it can be off by a week or more. An early ultrasound before 12 weeks is actually more accurate for dating the pregnancy and is considered the gold standard when there is a discrepancy with LMP dates.
What week is safe for delivery?
Full term is 37-42 weeks. Deliveries before 37 weeks are preterm. 39-40 weeks is considered optimal. Babies born at 37-38 weeks generally do well but have slightly higher rates of breathing difficulties compared to those born at 39+ weeks.
My cycle is not 28 days โ€” is the due date still accurate?
Our calculator adjusts for cycle length. If your cycle is longer, say 35 days, ovulation likely happens around day 21 instead of day 14, pushing your due date forward by about 7 days. Just enter your actual average cycle length for a more accurate estimate.
What are the signs of labour?
Signs that labour may be approaching include the baby dropping lower into the pelvis, loss of the mucus plug, water breaking, and regular contractions that increase in frequency and intensity. Contact your doctor when contractions are regular and about 5 minutes apart.