Week 5 marks the beginning of a critical development phase. The embryo is growing rapidly, and the foundations of the heart, brain, and spinal cord are taking shape. You may also be experiencing your first real pregnancy symptoms.
Your Baby This Week
Size: Sesame seed (about 2 mm)
The embryo now has three distinct layers of cells that will become every organ and tissue in the body:
- Ectoderm (outer layer): Brain, spinal cord, nerves, and skin
- Mesoderm (middle layer): Heart, bones, muscles, kidneys, and blood vessels
- Endoderm (inner layer): Lungs, liver, pancreas, and digestive tract
A primitive heart tube is forming and will begin beating sometime between now and week 6. The neural tube, which becomes the brain and spinal cord, is also developing.
Your Body
Pregnancy symptoms often kick in around week 5 as hCG levels climb rapidly:
- Nausea (with or without vomiting), often called morning sickness but it can happen any time of day
- Extreme fatigue
- Frequent urination as blood flow to the kidneys increases
- Sore breasts that may feel heavier or tingly
- Food aversions or cravings
If you have no symptoms, do not worry. Some people sail through early pregnancy feeling fine.
What to Do This Week
- Eat small, frequent meals to help manage nausea. Crackers, ginger, and cold foods tend to be easier on the stomach.
- Stay hydrated. Aim for at least 8 glasses of water per day.
- Avoid raw or undercooked meat, unpasteurized dairy, and high-mercury fish like swordfish and king mackerel.
Common Questions
Is it normal to have no symptoms at 5 weeks?
Yes. Symptoms vary widely between individuals and even between pregnancies. The absence of symptoms does not mean anything is wrong.
When will I hear the heartbeat?
A heartbeat can usually be detected on a transvaginal ultrasound between weeks 6 and 7. Your provider may schedule your first ultrasound for around week 8 to get a clearer picture.