1st TrimesterMonth 1Week 4 of 40
4 Weeks Pregnant
— How Many Months Is It?
4w
Equivalent to
Month 1
1st Trimester
🌾
Baby is the size of a
Poppy Seed
1 mm (~0.04 in)
🌱Fetal Development Milestones — Week 4
The primitive heart begins beating and circulating blood. Most sensitive home pregnancy tests detect hCG around this time.
Pregnancy timeline progress10%
Week 1Week 4Week 40
Calculate Your Exact Due Date
Enter your last period date for an instant gestational calculation
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Enter your date to calculate gestational age.
⚠️ Based on ACOG guidelines and Naegele's Rule for informational purposes only. Consult your OB-GYN.
Adjacent Pregnancy Weeks
Frequently Asked Questions — Week 4
4 weeks pregnant equals Month 1 of gestation in the 1st Trimester. Because calendar months vary between 28 and 31 days while weeks are exactly 7 days, clinical tracking in weeks provides the most accurate timeline.
The primitive heart begins beating and circulating blood. Most sensitive home pregnancy tests detect hCG around this time.
Use the calculator above: enter the first day of your last period (LMP) and the tool will calculate your exact estimated due date using Naegele\'s Rule (LMP + 280 days).