Question 1

How many weeks pregnant am I from my due date?

Accepted Answer

Subtract the number of days until your due date from 280 (total pregnancy days), then divide by 7 to get weeks. For example, if your due date is 90 days away: 280 - 90 = 190 gestational days = 27 weeks and 1 day pregnant. This calculator does the math instantly when you enter your due date.

Question 2

What trimester am I in based on my due date?

Accepted Answer

First trimester: weeks 1-12 (more than 196 days remaining). Second trimester: weeks 13-27 (91-196 days remaining). Third trimester: weeks 28-40 (0-90 days remaining). The transition between trimesters is based on completed gestational weeks, not exact days.

Question 3

Can I calculate my LMP from my due date?

Accepted Answer

Yes. Your estimated LMP (last menstrual period) date is 280 days before your due date. If your due date is July 15, your estimated LMP was approximately October 8 of the previous year. This assumes a standard 28-day cycle with ovulation on day 14.

Question 4

Why does my doctor use a different due date than my LMP calculation?

Accepted Answer

Doctors often adjust the due date based on first-trimester ultrasound measurements, which can be more accurate than LMP-based dating. Ultrasound dating is most accurate between weeks 8 and 13 and can differ from LMP calculations by 5-7 days. If the ultrasound date differs by more than 7 days from LMP, most practitioners will use the ultrasound date.

Question 5

What percentage of babies are born on their due date?

Accepted Answer

Only about 4-5% of babies are born on their exact due date. About 80% are born within 2 weeks of the due date (between weeks 38 and 42). First-time mothers tend to deliver slightly later (average 5 days past due date), while subsequent pregnancies tend to arrive closer to the due date or slightly earlier.

Question 6

How accurate is a due date calculated from LMP?

Accepted Answer

LMP-based due dates assume a 28-day cycle with ovulation on day 14, which applies to about 10-15% of women. Actual cycle lengths vary from 21 to 35 days, and ovulation can occur on any day between days 11 and 21. This is why first-trimester ultrasound dating (accurate to plus or minus 3-5 days) is preferred for confirming or adjusting the due date.

Week	Trimester	Milestone	Baby Size
6	1st	Heartbeat detectable on ultrasound	Lentil (3 mm)
12	1st	End of first trimester, organs formed	Lime (5 cm)
16	2nd	Gender may be visible on ultrasound	Avocado (12 cm)
20	2nd	Anatomy scan, halfway point	Banana (25 cm)
24	2nd	Viability milestone	Corn (30 cm)
28	3rd	Third trimester begins	Eggplant (38 cm)
37	3rd	Early term (safe for delivery)	Watermelon (48 cm)
40	3rd	Full term, expected due date	Watermelon (50 cm)

Calculadora de Semana de Embarazo por Fecha de Parto

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Como Calcular Semanas de Embarazo desde tu Fecha de Parto

Pregnancy Milestones by Week

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