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First Trimester (Weeks 1 - 13) Week 13 of 40
Fetal Size Comparison

Week 13 Size: Lemon

About the size of a juicy lemon.

Length 7.4 cm 2.9 inches
Weight 23 g 0.8 oz

Relative Visual Scale

Solid circle represents your baby's size. Dotted circle shows the full-term week 40 size threshold.

Inside The Womb

Baby's Development

This is the final week of the first trimester. The baby has unique fingerprints! Vocal cords are beginning to form, and the intestines are moving from the umbilical cord into the abdomen.

Weekly Milestones

  • End of Trimester 1
  • Fingerprints Formed
Maternal Health

Your Body & Symptoms

Your energy levels are returning, and nausea is fading. Your libido might increase. The risk of miscarriage drops significantly after this week.

Common Symptoms this Week

Increased energy Higher sex drive Visible baby bump Leukorrhea (milky discharge)

Doctor & Care Recommendations

  • Start looking into maternity clothes or belly bands.
  • Discuss a birth plan draft with your partner.
  • Enjoy the boost in energy; do some light nesting or plan a babymoon.
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PregWeeks

CHECKLIST

Ultimate Hospital Bag & Birth Plan

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The Ultimate Hospital Bag Checklist & Birth Plan PDF

Prepare for labor with confidence. Our doctor-reviewed checklists ensure you don't forget any newborn or partner essentials in the hospital delivery room.

  • Clinical OB-GYN Approved List: Separate checklists detailing exactly what mom, partner, and newborn baby require for a standard 3-day recovery stay.
  • 10-Second Birth Preference Builder: Minimalist visual plan templates designed to help delivery nurses digest your labor choices instantly on check-in.
  • 1-Click Offline Access: High-resolution, print-ready document formatted to download directly to your mobile device for offline reference in the clinic.

Weekly Health Guides & Resources

Trimester Guide

First Trimester Guide

Read comprehensive clinical milestones, screening checklists, and developmental guidelines for this phase.

Explore Trimester →
Common Symptoms

Track & Relieve Symptoms

Learn why symptoms occur, home remedies, and clinical indicators for this week:

Pregnancy Nutrition

Food Safety Checklists

Verify safety statuses, listeria and mercury risks, and safe alternatives for:

Full Nutrition Guide →

Frequently Asked Questions: Week 13

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Evidence-Based Clinical Sources for Week 13

PregWeeks is dedicated to medical transparency. Every milestone, symptom tip, and fetal development guideline for Week 13 is sourced directly from clinical guidelines published by leading obstetric authorities. Read more about our editorial methodology on our Medical Sources page.

Nutrition During Pregnancy FAQ

ACOG

Patient and practitioner reference guidelines on prenatal nutritional intake, including essential vitamins, iron, calcium, and weight thresholds.

View Clinical Guideline

Early Pregnancy Loss (Practice Bulletin No. 200)

ACOG

Clinical guidelines on diagnostics, physical symptoms, and care options during early pregnancy challenges in the first trimester.

View Clinical Guideline

Food Safety for Pregnant Women

FDA / CDC

Standard warnings and food safety guidelines regarding Listeria, Salmonella, and mercury levels in seafood during gestation.

View Clinical Guideline
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🏥 Medical Disclaimer

PregWeeks is an educational planning tool and does not provide clinical diagnoses or medical advice. Always consult your obstetrician or healthcare professional for health concerns.