16 weeks pregnant: your baby & body
Your baby this week
About 11.6 cm and 100 g — around the size of a avocado. Every baby grows a little differently.
How your baby is developing
- Facial muscles are developing, so small expressions like grimacing become possible.UNSW Embryology (CC-BY)
- The circulatory system and urinary tract are typically fully functioning by now.UNSW Embryology (CC-BY)
How you may feel
- The bump is often becoming more visible; standing up quickly can occasionally cause mild dizziness as blood volume increases.NHS
- Some, especially in a subsequent pregnancy, begin to feel the first flutters of movement ('quickening') around now.ACOG
Nutrition this week
Tests & scans
- Quad / triple serum screen (if first-trimester screen not done)
When to reach out
- Heavy vaginal bleeding or passing clots.ACOG
- Severe or persistent abdominal or pelvic pain.ACOG
- Severe, persistent nausea or vomiting that prevents keeping any fluids down (possible hyperemesis gravidarum).NHS
- Fever of 38°C (100.4°F) or higher, or chills.WHO
- Severe dizziness, fainting, or a racing/irregular heartbeat.NHS
- Pain or burning when urinating (possible urinary tract infection).NHS
- A severe or persistent headache that doesn't improve.ACOG
- Sudden swelling of the face, hands, or feet.ACOG
- Visual disturbances — blurring, flashing lights, or spots.ACOG
- Fluid leaking or gushing from the vagina (possible ruptured membranes).NHS
- Persistent pain in the upper abdomen, especially under the ribs on the right side.ACOG
These apply to this week specifically. See the full list of urgent warning signs the CDC publishes for pregnancy and the year after birth.
Part of the Second trimester (weeks 14–27).
Educational reference only — not medical advice. Typical/average figures; every pregnancy differs. Always consult your doctor or midwife. Seek urgent care for any warning sign.