18 weeks pregnant: your baby & body
Your baby this week
About 14.2 cm and 190 g — around the size of a bell pepper. Every baby grows a little differently.
How your baby is developing
- The ears have typically reached their final position, and the fetus may begin responding to sounds from outside the womb.UNSW Embryology (CC-BY)
- Yawning and hiccupping have been observed on ultrasound at this stage.UNSW Embryology (CC-BY)
How you may feel
- Many people feel the baby's first movements by now if they haven't already.ACOG
- Increased vaginal discharge and a shifting sense of balance as the bump grows are common.NHS
Nutrition this week
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.