Pregnancy Calculator – Due Date & Week Calculator

Pregnancy Calculator

Last Menstrual Period (LMP) Conception Date Due Date
Current Date
Cycle Length ?days
Luteal Phase Length ?days
 

Due Date:   Select calculation method Current Pregnancy Week– Days Until Due Date– Estimated Conception Date– First Trimester– Second Trimester– Third Trimester– Estimated Fetal Age– Next Prenatal Visit–
Pregnancy Progress 1st 2nd 3rd 1st Trimester (0-12 weeks) 2nd Trimester (13-27 weeks) 3rd Trimester (28-40 weeks)

Pregnancy Milestones

Pregnancy Week 0 10 20 30 40 4 8 12 16 20 24 28 32 36

WeekBaby DevelopmentMother Changes
4Neural tube formsMissed period
8Major organs developMorning sickness begins
12Fingers and toes formEnd of first trimester
16Gender can be determinedEnergy returns
20Halfway point reachedBaby movements felt
24Viability milestoneGlucose screening
28Eyes can openThird trimester begins
32Rapid brain developmentBraxton Hicks contractions
36Lungs nearly matureBaby considered full-term soon
40Ready for birthDue date arrives

Related ToolsOvulation Calculator | Fertility Calculator | Baby Name Generator


The Pregnancy Calculator is designed to help expectant mothers track their pregnancy progress and estimate important dates. This tool calculates your due date, current pregnancy week, and provides valuable information about fetal development milestones.

How Pregnancy is Calculated

Pregnancy is typically calculated from the first day of your last menstrual period (LMP), even though conception usually occurs about two weeks later. This method, called gestational age, is the standard used by healthcare providers worldwide. A full-term pregnancy lasts approximately 40 weeks or 280 days from the LMP.

Calculation Methods

Our pregnancy calculator offers three different calculation methods to accommodate various scenarios:

  • Last Menstrual Period (LMP) – The most common method used by healthcare providers. Enter the first day of your last period to calculate your due date.
  • Conception Date – If you know when conception occurred (such as through IVF or fertility tracking), this method provides more precise calculations.
  • Due Date – If your healthcare provider has given you a due date based on ultrasound measurements, use this to work backwards and determine other important dates.

Pregnancy Trimesters

Pregnancy is divided into three trimesters, each lasting approximately 13-14 weeks:

  • First Trimester (Weeks 1-12) – Critical period for organ development. Morning sickness and fatigue are common. Risk of miscarriage is highest during this period.
  • Second Trimester (Weeks 13-27) – Often called the “golden period” of pregnancy. Energy levels typically improve, and you may start feeling baby movements around week 18-20.
  • Third Trimester (Weeks 28-40) – Rapid fetal growth occurs. Prepare for labor and delivery. Regular prenatal visits become more frequent.

Important Pregnancy Milestones

Throughout pregnancy, there are several key milestones and appointments to be aware of:

  • Week 4-6 – Confirm pregnancy with home test and schedule first prenatal appointment
  • Week 8-12 – First prenatal visit, initial blood work, and possible first ultrasound
  • Week 11-14 – Optional nuchal translucency screening for genetic abnormalities
  • Week 15-20 – Maternal serum screening and detailed anatomy ultrasound
  • Week 24-28 – Glucose tolerance test for gestational diabetes
  • Week 35-37 – Group B streptococcus (GBS) screening
  • Week 36-40 – Weekly prenatal visits and monitoring for labor signs

Factors Affecting Due Date Accuracy

While pregnancy calculators provide estimated due dates, several factors can affect accuracy:

  • Irregular Menstrual Cycles – Women with irregular cycles may ovulate at different times, affecting conception date calculations.
  • Cycle Length Variations – The standard 28-day cycle assumption may not apply to all women. Cycles can range from 21-35 days.
  • Ovulation Timing – Ovulation doesn’t always occur exactly 14 days before the next period, especially in longer or shorter cycles.
  • First vs. Subsequent Pregnancies – First-time mothers often deliver slightly past their due date, while experienced mothers may deliver earlier.

When to Consult Your Healthcare Provider

While pregnancy calculators are helpful tools, always consult with your healthcare provider for:

  • Confirmation of pregnancy and due date
  • Establishing a prenatal care schedule
  • Discussing any concerns or complications
  • Adjusting due dates based on ultrasound measurements
  • Planning for delivery and postpartum care

Prenatal Care Schedule

Regular prenatal care is essential for a healthy pregnancy. The typical schedule includes:

  • Weeks 4-28 – Monthly appointments
  • Weeks 28-36 – Bi-weekly appointments
  • Weeks 36-40 – Weekly appointments
  • Past 40 weeks – Twice-weekly monitoring until delivery

Nutrition and Lifestyle During Pregnancy

Maintaining a healthy lifestyle is crucial throughout pregnancy:

  • Prenatal Vitamins – Take folic acid (400-800 mcg daily) and other essential nutrients
  • Healthy Diet – Focus on fruits, vegetables, whole grains, lean proteins, and dairy products
  • Hydration – Drink plenty of water (8-10 glasses daily)
  • Exercise – Engage in moderate exercise as approved by your healthcare provider
  • Avoid Harmful Substances – No alcohol, smoking, or recreational drugs
  • Limit Caffeine – Keep caffeine intake under 200mg per day

Common Pregnancy Symptoms by Trimester

First Trimester Symptoms:

  • Missed period and positive pregnancy test
  • Morning sickness and nausea
  • Breast tenderness and enlargement
  • Fatigue and increased need for sleep
  • Frequent urination
  • Food aversions and cravings

Second Trimester Symptoms:

  • Decreased nausea and increased energy
  • Visible baby bump development
  • First baby movements (quickening)
  • Skin and hair changes
  • Possible heartburn and constipation
  • Round ligament pain

Third Trimester Symptoms:

  • Increased baby movements and hiccups
  • Braxton Hicks contractions
  • Shortness of breath
  • Swelling in feet and ankles
  • Difficulty sleeping
  • Pelvic pressure and back pain
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