A big milestone: starting this week, the embryo is officially called a fetus. All the essential organs have begun forming, and the rest of pregnancy is about growth, maturation, and refinement. The tail is gone, and the fetus looks increasingly human.
Your Baby This Week
Size: Cherry (about 23 mm, or just under 1 inch)
Weight: About 2 grams
- Muscles: Forming throughout the body. The fetus can make small, jerky movements.
- Bones: Cartilage is starting to harden into bone in some areas
- Heart: Four chambers are fully formed and beating strongly
- Face: Eyes are fully formed but fused shut. Earlobes are visible.
- Fingers and toes: Separated and distinct. Touch pads are developing on the fingertips.
- Reproductive organs: Internal development continues, though sex determination on ultrasound is still weeks away
Your Body
- Nausea still going strong for many, but relief is on the horizon
- Waistline thickening: Clothes may feel snug, even though a visible bump is still weeks away
- Emotional changes: Mood swings, irritability, or unexpected tearfulness are common
- Nasal congestion: Increased blood volume can cause stuffiness, called pregnancy rhinitis
- Visible veins: Blue veins may become more prominent on your breasts and abdomen
What to Do This Week
- Learn about first-trimester screening. Between weeks 11 and 14, you may be offered a nuchal translucency ultrasound and blood test to screen for chromosomal conditions like Down syndrome.
- Look into NIPT. Non-invasive prenatal testing (a simple blood draw) can screen for chromosomal abnormalities as early as week 10 with high accuracy.
- Move your body. Even a 20-minute walk daily supports circulation, mood, and sleep.
Common Questions
What is the difference between an embryo and a fetus?
The embryonic period (weeks 3 to 8) is when all major organ systems are established. From week 9 onward, the developing baby is called a fetus, and the focus shifts to growth and maturation of those existing structures.
Is it normal to not "feel" pregnant?
Absolutely. Symptoms fluctuate throughout pregnancy. Some weeks you may feel very pregnant, and others you may forget entirely. Both are normal.