familia

Pregnancy Calendar Week-by-Week

Q: What does 'EDD' mean?

**Estimated Due Date.** It's the predicted date of spontaneous labor, calculated as LMP + 280 days (or Naegele's Rule: last period month + 9, day + 7).

Q: When should I schedule my first prenatal visit?

Ideally between **8–10 weeks gestation**, when a dating ultrasound can confirm viability and refine the due date. If you have risk factors, see your provider earlier.

Q: Why is the NT scan at 11–13 weeks?

The **nuchal translucency (NT) ultrasound** at 11 weeks 0 days to 13 weeks 6 days measures fluid at the back of the fetal neck. Combined with bloodwork, it screens for Down syndrome (Trisomy 21) and other chromosomal abnormalities with ~85% detection.

Q: What is the anatomy ultrasound?

Performed at **18–22 weeks**, this detailed ultrasound examines fetal organs, limbs, spine, heart chambers, and placenta position. It can also reveal fetal sex and diagnose many structural abnormalities.

Q: Why the glucose test at 24–28 weeks?

The **gestational diabetes screening** is done at 24–28 weeks because placental hormones peak, increasing insulin resistance. Early detection prevents complications for mother and baby.

Q: What is the Group B Strep test?

At **35–37 weeks**, a vaginal/rectal swab detects *Streptococcus agalactiae*. If positive, IV antibiotics during labor prevent neonatal infection. Test results don't affect pregnancy, only labor management.

Q: What weeks are 'safe' vs. 'risky'?

Miscarriage risk is highest in **weeks 1–12** (spontaneous loss ~15% overall, higher with age). After 12 weeks, risk drops sharply. **Weeks 13–27** are safest for travel and physical activity in uncomplicated pregnancies. **Weeks 28+** require monitoring for preterm labor signs.

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Data updated: 28 abr 2026 · Source: American College of Obstetricians and Gynecologists (ACOG) – Guidelines for Perinatal Care

Reviewed by: Hacé Cuentas editorial team (política editorial ) · Last reviewed: 28 abr 2026

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Track your pregnancy from conception through delivery with a detailed week-by-week calendar. Enter your last menstrual period (LMP) or due date to generate a complete pregnancy timeline showing fetal development milestones, baby size comparisons, and the dates of critical prenatal appointments. This calendar follows standard obstetric dating conventions (280 days / 40 weeks from LMP) and highlights first, second, and third trimester boundaries.

Last reviewed: May 12, 2026 Verified by Hacé Cuentas Team Source: American College of Obstetricians and Gynecologists (ACOG) – Guidelines for Perinatal Care, WHO – Pregnancy, Childbirth, Postpartum and Newborn Care, CDC – Pregnancy & Childbirth Health Topics, UpToDate – Pregnancy: Estimate Delivery Date, NIH – Prenatal Care and Tests 100% private

When to use this calculator

Track fetal development size and growth week-by-week
Identify when to schedule prenatal screening tests
Plan maternity leave and hospital visits
Monitor trimester transitions and milestone dates
Share pregnancy progress with healthcare providers
Prepare for major appointments and ultrasounds

How it works

2 min read

What is a pregnancy calendar?

A pregnancy calendar is a week-by-week timeline that tracks fetal development from conception through delivery, typically spanning 40 weeks. It maps critical milestones like the anatomy ultrasound at 18–22 weeks and gestational diabetes screening at 24–28 weeks. This tool helps expectant parents monitor prenatal appointments and understand baby growth stages accurately.

How Pregnancy Dating Works

Obstetric dating counts pregnancy from the first day of the last menstrual period (LMP), not from conception. This convention standardizes pregnancy duration at 280 days or 40 weeks, even though fertilization occurs about 2 weeks after LMP.

LMP (Week 0) → Conception (~Week 2) → Due Date (Week 40)

Trimester Boundaries

First Trimester: Weeks 1–13 (Day 1 to Day 91)

Second Trimester: Weeks 14–27 (Day 92 to Day 189)

Third Trimester: Weeks 28–40+ (Day 190 onward)

Baby Size Milestones (Week-by-Week)

Fetal development follows predictable growth patterns. Common size comparisons:

Week	Size Comparison	CRL (cm)	Weight
8	Raspberry	1.6	<1 g
12	Poppy seed	5.4	14 g
16	Avocado	11.6	100 g
20	Banana	16.4	300 g
24	Corn on the cob	20	600 g
28	Eggplant	25	1.0 kg
32	Squash	28	1.7 kg
36	Romaine lettuce	32	2.6 kg
40	Watermelon	36	3.4 kg

Key Prenatal Appointments

Weeks 8–10: Confirm pregnancy, dating ultrasound, initial bloodwork

Weeks 11–13: Nuchal translucency (NT) scan (screens for chromosomal abnormalities)

Weeks 15–20: Quad screen and integrated screening (first/second trimester combined)

Weeks 18–22: Anatomy ultrasound (fetal anatomy, fetal sex, placenta position)

Weeks 24–28: Gestational diabetes screening (oral glucose tolerance test)

Weeks 28–34: RhoGAM (if Rh-negative), repeat bloodwork

Weeks 35–37: Group B Streptococcus (GBS) vaginal/rectal swab

Weeks 36–40: Biweekly then weekly visits; cervical exams; NST monitoring if post-term

Worked Example

Input: LMP = January 15, 2026

Due Date: October 22, 2026 (280 days later)

Week 20 date: May 27, 2026 (Anatomy ultrasound window)

Week 28 date: July 22, 2026 (Begin third trimester)

Baby size at Week 20: Banana (16.4 cm CRL, ~300 g)

Weeks remaining (as of April 28, 2026): ~26 weeks

When NOT to Apply / Limitations

Irregular cycles: If your cycle is <21 or >35 days, LMP dating may be inaccurate; ultrasound dating (first trimester) is preferred.

Assisted reproduction: Frozen embryo transfer and IVF dates should be counted from transfer date, not LMP.

Multiple gestations: Twin/triplet pregnancies often deliver earlier; adjust expectations accordingly.

Post-term pregnancy: Pregnancies continuing beyond 40 weeks require specialist monitoring and may be induced.

This calculator is educational: Always confirm dates and milestones with your healthcare provider via ultrasound.

Frequently asked questions

What if my cycle is irregular?

LMP dating works best for regular 28-day cycles. If your cycle is irregular, a first-trimester ultrasound (before 13 weeks + 6 days) is the most accurate dating method and can adjust your due date by ±3 days.

How accurate is the due date?

Due dates are estimates. Only about 5% of babies arrive on the exact due date. Most pregnancies deliver within ±2 weeks of the due date. Ultrasound dating in the first trimester has an accuracy of ±3–5 days.

What does 'EDD' mean?

Estimated Due Date. It's the predicted date of spontaneous labor, calculated as LMP + 280 days (or Naegele's Rule: last period month + 9, day + 7).

When should I schedule my first prenatal visit?

Ideally between 8–10 weeks gestation, when a dating ultrasound can confirm viability and refine the due date. If you have risk factors, see your provider earlier.

Why is the NT scan at 11–13 weeks?

The nuchal translucency (NT) ultrasound at 11 weeks 0 days to 13 weeks 6 days measures fluid at the back of the fetal neck. Combined with bloodwork, it screens for Down syndrome (Trisomy 21) and other chromosomal abnormalities with ~85% detection.

What is the anatomy ultrasound?

Performed at 18–22 weeks, this detailed ultrasound examines fetal organs, limbs, spine, heart chambers, and placenta position. It can also reveal fetal sex and diagnose many structural abnormalities.

Why the glucose test at 24–28 weeks?

The gestational diabetes screening is done at 24–28 weeks because placental hormones peak, increasing insulin resistance. Early detection prevents complications for mother and baby.

What is the Group B Strep test?

At 35–37 weeks, a vaginal/rectal swab detects Streptococcus agalactiae. If positive, IV antibiotics during labor prevent neonatal infection. Test results don't affect pregnancy, only labor management.

Can I have sex during pregnancy?

Yes, unless your provider advises otherwise (e.g., placenta previa, preterm labor risk). Sex does not cause miscarriage or induce labor in healthy pregnancies.

What weeks are 'safe' vs. 'risky'?

Miscarriage risk is highest in weeks 1–12 (spontaneous loss ~15% overall, higher with age). After 12 weeks, risk drops sharply. Weeks 13–27 are safest for travel and physical activity in uncomplicated pregnancies. Weeks 28+ require monitoring for preterm labor signs.