Week 21 of pregnancy

Your baby this week

About 398 g (estimated weight; Source: WHO fetal growth charts (Kiserud et al., PLoS Med 2017)) — about as heavy as a mooli (white radish, about 7 in long) (Source: USDA SR Legacy (FoodData Central) FDC 168451 'Radishes, oriental, raw': portion '1 radish (7" long)' = 338 g edible portion; SR28 FOOD_DES refuse 21% (Tops and parings). As-purchased weight = 338 / (1 - 0.21) = 427.8 g.). Every baby grows a little differently.

How your baby is developing

• Movements are becoming more coordinated as the nervous system matures.UNSW Embryology (CC-BY)
• The digestive system is developing further, allowing some absorption of nutrients from swallowed amniotic fluid.UNSW Embryology (CC-BY)

How you may feel

• Appetite continues to increase; leg cramps, especially at night, are common from around now.NHS

Nutrition this week

• Iron — blood volume rises ~50% — iron demand climbs (Red meat)
• Calcium — fetal skeleton mineralising (Dairy)
• Vitamin D — calcium absorption + bone (Fatty fish)

Tests & scans

• Anomaly (mid-pregnancy) ultrasound (weeks 18–22)

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.