Pregnancy Milestone Timeline
Trimester Overview
- Fertilized egg implants in uterine wall around week 4
- Heart begins beating by week 6 — first heartbeat detectable on ultrasound
- All major organs begin forming — neural tube closes by week 6
- Morning sickness peaks around weeks 8–10, fatigue is common
- First prenatal visit typically between weeks 6–8
- Risk of miscarriage drops significantly after week 12
- Baby grows from a poppy seed to about 2.5 inches long
- Energy often returns — many call this the "honeymoon trimester"
- Baby bump becomes visible around weeks 16–20
- You may feel first movements (quickening) around weeks 16–22
- Anatomy scan ultrasound at week 20 — can often reveal baby's sex
- Baby can hear sounds by week 18 and responds to light by week 22
- Viability milestone reached around week 24
- Baby grows from about 3 inches to over 14 inches long
- Baby gains about half a pound per week as fat layers develop
- Braxton Hicks contractions (practice contractions) may begin
- Baby typically moves into head-down position by weeks 32–36
- Lungs mature — full term begins at week 37
- Prenatal visits increase to weekly starting around week 36
- Nesting instinct may kick in as due date approaches
- Most babies arrive between weeks 39–41, weighing 6–9 pounds
This guide provides general information only and is not a substitute for professional medical advice. Every pregnancy is unique — development timelines and symptoms can vary significantly. Always consult your healthcare provider for personalized prenatal care and guidance throughout your pregnancy.
Your Complete Pregnancy Week-by-Week Guide
Pregnancy lasts approximately 40 weeks from the first day of your last menstrual period. Each week brings new developments for your baby and changes in your body. Understanding what's happening at each stage helps you prepare, know what to expect, and identify when something might need medical attention.
How Pregnancy Weeks Are Counted
Pregnancy weeks are counted from the first day of your last menstrual period (LMP), not from conception. This means that during weeks 1 and 2, you aren't actually pregnant yet — conception typically occurs around week 2 or 3. By the time you miss your period and get a positive test, you're usually already about 4 weeks along.
Baby Size Comparisons by Week
One of the most popular ways to visualize your baby's growth is through fruit and vegetable comparisons. Your baby starts as a tiny poppy seed at week 4, grows to a blueberry by week 7, reaches the size of a lemon by week 14, and continues growing until reaching the size of a small watermelon at full term. These comparisons give you a tangible sense of your baby's size at each stage.
Key Pregnancy Milestones
Several important milestones mark the journey from conception to birth:
- Week 6: First heartbeat can be detected via ultrasound
- Week 10: NIPT blood test available for genetic screening
- Week 12: End of first trimester — miscarriage risk drops significantly
- Week 16–20: First fetal movements may be felt
- Week 20: Anatomy scan — baby's sex can often be determined
- Week 24: Viability milestone — survival possible with intensive care
- Week 37: Full term — baby's lungs are typically mature
Common Symptoms Throughout Pregnancy
Pregnancy symptoms vary widely between individuals and even between different pregnancies for the same person. First trimester symptoms often include nausea, extreme fatigue, breast tenderness, and frequent urination. The second trimester typically brings relief from nausea but may introduce back pain, round ligament pain, and visible body changes. The third trimester often involves Braxton Hicks contractions, swelling in the feet and ankles, heartburn, and difficulty sleeping as the baby grows larger.