Pregnancy Weeks Calculator

📊 Pregnancy Week Checker

Check current pregnancy week and fetal development based on LMP

First Day of LMP

Menstrual Cycle Length 28 Days 21 Days 22 Days 23 Days 24 Days 25 Days 26 Days 27 Days 29 Days 30 Days 31 Days 32 Days 33 Days 34 Days 35 Days

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Usage Tips

• Please accurately enter the first day of your last menstrual period
• For women with irregular menstrual cycles, the calculation may have slight errors
• Fetal development is a general reference, individual differences are large
• If you have any doubts, please consult a professional doctor

Instructions

The Pregnancy Weeks Calculator is a professional pregnancy tool that helps expectant mothers:

• Calculate Current Week Accurately: Precisely calculate the current pregnancy week and days based on the last menstrual period and cycle length.
• Understand Fetal Development: Provide information on fetal size, weight, organ development, and sensory development for different weeks.
• Get Personalized Advice: Provide corresponding advice on nutrition, exercise, prenatal checkups, and monitoring for different pregnancy stages.
• Preview Next Week's Changes: Understand fetal development and physical changes for the next week to prepare in advance.

Calculation Principle

Pregnancy Week Calculation Method

1. Basic Calculation: Starting from the first day of the last menstrual period, every 7 days counts as 1 pregnancy week.
2. Cycle Adjustment: Adjust the due date based on individual menstrual cycle length (21-35 days).
3. Pregnancy Stages:
   • First Trimester: Weeks 1-12
   • Second Trimester: Weeks 13-28
   • Third Trimester: Weeks 29-40

Due Date Calculation

• Standard Algorithm: Last Menstrual Period Date + 280 days (40 weeks)
• Cycle Adjustment: Add the difference of (Actual Cycle - 28 days) to the due date.

Fetal Development Stages

First Trimester (Weeks 1-12)

• Size: About 1-2 cm → 5-6 cm
• Weight: About 1-2 g → 10-20 g
• Development Focus: Organs begin to form, heart starts beating, taking human shape.

Second Trimester (Weeks 13-28)

• Size: About 5-6 cm → 25-30 cm
• Weight: About 10-20 g → 300-600 g
• Development Focus: Rapid organ development, fetal movement appears, hearing development completes.

Third Trimester (Weeks 29-40)

• Size: About 25-30 cm → 45-50 cm
• Weight: About 300-600 g → 3000-4000 g
• Development Focus: Organs mature and perfect, lungs mature, all systems develop perfectly.

Important Notes

Usage Suggestions

• Please accurately enter the date of the first day of your last menstrual period.
• For women with irregular menstrual cycles, the calculation may have a slight error.
• Fetal development information is for general reference; individual differences are significant.
• Regular prenatal checkups and doctor's examination results shall prevail.

Important Reminder

• This tool is for reference only and cannot replace professional medical advice.
• If you have any health concerns, please consult a professional doctor promptly.
• Every pregnant woman's constitution and fetal development are different.
• Please manage your pregnancy under the guidance of a professional doctor.

FAQ

Q: What if my menstrual cycle is irregular?

A: You can enter the average cycle length, but the calculation result may have some error. It is recommended to confirm the pregnancy week in combination with ultrasound results.

Q: How to judge if fetal movement is normal?

A: You can start to feel fetal movement around 18-20 weeks, and it becomes regular after 28 weeks. 3-5 movements per hour, or 30-40 distinct movements in 12 hours is considered a normal range.

Q: What should I pay attention to in different weeks?

A:

• First Trimester: Take folic acid, avoid strenuous exercise, regular checkups.
• Second Trimester: Balanced nutrition, moderate exercise, pay attention to fetal movement.
• Third Trimester: Control weight, prepare for delivery, close monitoring.

Q: Is the due date accurate?

A: Only 5% of babies are born on their due date. Most are born within two weeks before or after the due date, which is normal.

Related Links

• Due Date Calculator - Calculate due date and important pregnancy milestones
• Weight Tracker - Record and monitor pregnancy weight gain
• Fetal Movement Counter - Record fetal movement and monitor baby's health

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Gentle Reminder: All information provided by this tool is for reference only. Please follow professional medical advice for specific pregnancy management.