Weeks 1–13
First Trimester
The beginning of everything
The first trimester is when your baby's major organs and body systems form. It's often the most physically challenging — morning sickness, fatigue, and rapid hormonal changes are common.
Baby Development Milestones
Wk 4Embryo implants in the uterus. Heart begins to form.
Wk 6Heartbeat detectable. Brain and spinal cord developing.
Wk 8All major organs have begun forming. Tiny fingers and toes appear.
Wk 10Officially a fetus. Facial features becoming distinct.
Wk 12Fingernails forming. Can make a fist. Most miscarriage risk has passed.
Common Symptoms
- Morning sickness / nausea
- Extreme fatigue
- Breast tenderness
- Food aversions or cravings
- Frequent urination
- Mood swings
- Bloating
- Heightened sense of smell
Prenatal Appointments
- First prenatal visit (8–10 weeks)
- Blood tests and urine tests
- Dating ultrasound
- NIPT or genetic screening (optional, 10–13 weeks)
- Nuchal translucency scan (11–14 weeks)
Quick Facts
- Duration: 13 weeks
- Weeks 1 through 13
- Months 1–4 of pregnancy
- Risk of miscarriage drops significantly at week 12
Tips for the First Trimester
- Start taking prenatal vitamins with folic acid
- Avoid alcohol, raw fish, high-mercury fish, and unpasteurized cheeses
- Stay hydrated — it helps with nausea
- Rest when you can; fatigue is intense and normal
- It's fine to wait until 12 weeks to share the news