21 Weeks Pregnant
At 21 weeks pregnant your baby is about the size of a large carrot — roughly 10.5 inches and around 12 to 13 ounces — with movements that have become coordinated and frequent. Many parents say this is the week flutters turn into definite kicks. Extra blood volume and a heavier uterus may bring varicose veins, leg cramps, and other circulation quirks.
Your week at a glance
| This week | Details |
|---|---|
| Baby size | About a large carrot, roughly 26.7 cm (10.5 in) and ~360 g (12–13 oz) |
| What is developing | Coordinated movement, eyebrows, tear ducts, bone marrow making blood cells, taste buds |
| Your symptoms | Varicose veins, hemorrhoids, nighttime leg cramps, stretch marks, deepening linea nigra |
| To-do | Hydrate, stretch your calves before bed, flag glucose-screening risk factors with your provider |
How big is your baby at 21 weeks?
Your baby is about the size of a large carrot this week — roughly 10.5 inches long and around 12 to 13 ounces (about 360 grams). Movements have become coordinated and frequent. The early jerky reflexes of earlier weeks are smoothing out into purposeful kicks, stretches, somersaults, and slow rolls. Many parents say week 21 is when the flutters they have been wondering about start to feel like definite movement. Inside, the bone marrow has taken over a major job that the liver and spleen had been handling: producing red and white blood cells. Tiny eyebrows are sprouting, the tear ducts are forming, and the very first hairs on the scalp may be showing up.
Your baby's digestive system is rehearsing for life on the outside, too. Small amounts of amniotic fluid are being swallowed each day, the intestines are practicing absorbing sugars and fluids, and a sticky, dark substance called meconium is starting to build up in the bowel — this will become your baby's very first diaper after birth. The taste buds are functioning, and what you eat actually flavors the amniotic fluid mildly, giving your baby an early preview of family flavors. The senses are sharpening: your baby can hear your voice clearly through the muffle of your body and can move suddenly in response to loud sounds. The pattern is still irregular at this stage, so do not panic if a day passes with little movement; a consistent daily routine usually emerges closer to weeks 24 to 28.
21 weeks pregnant symptoms
By week 21, your blood volume has climbed close to 50 percent above your pre-pregnancy level, and your growing uterus is gently pressing on the big veins that carry blood back up from your legs. That brings a cluster of very common circulation quirks. These are the common, normal symptoms this week:
- Varicose veins on the legs or around the vulva, plus spider veins on the cheeks and chest, as progesterone relaxes blood-vessel walls
- Hemorrhoids — essentially varicose veins of the rectum — and leg cramps that wake you in the middle of the night
- Stretch marks — pink or purple streaks on the belly, breasts, hips, or thighs, largely down to genetics
- A deepening linea nigra, mild end-of-day swelling in the feet and ankles, a stuffy nose, occasional nosebleeds, and bleeding gums when you brush
- A returning appetite, faster-growing hair and nails, and a real growth spurt in the bump itself
Your center of gravity keeps shifting, so your lower back may protest more by the end of the day, and the hormone relaxin loosening your joints can make you feel a little clumsier — take stairs carefully and skip the high heels. The second trimester is often called the "honeymoon" of pregnancy, but feeling good is not universal, and body-image shifts hit hard for some people. Be gentle with yourself and bring up anything weighing on you at your next visit.
Taking care of yourself this week
Small daily moves go a long way for second-trimester circulation. Stretch your calves before bed — point and flex your feet, draw circles with your ankles, or gently lean against a wall — to help head off nighttime leg cramps. Avoid sitting or standing in one position for too long; if you have a desk job, set a quiet reminder to get up and walk around every 30 to 45 minutes.
- Maternity compression socks can ease leg heaviness and end-of-day swelling.
- Elevate your feet when you sit, sleep mostly on your side with a pillow between your knees, and stay well hydrated.
- Plenty of fluids and fiber — whole grains, beans, lentils, fruit with the skin on, vegetables, and chia or flaxseed — help with hemorrhoids and constipation. Ask your provider before adding any stool softener.
- A prenatal massage from a certified prenatal therapist is genuinely helpful right now; make sure they use a side-lying or pregnancy-cushion setup.
On food safety, keep avoiding raw or undercooked fish like sushi, sashimi, ceviche, and oysters, along with high-mercury fish (swordfish, king mackerel, tilefish, shark, bigeye tuna). Cook all eggs until firm, heat deli meats until steaming, and stick with pasteurized dairy. This is also a great week to start thinking about a safe sleep space: a flat, firm mattress in a crib or bassinet that meets current US Consumer Product Safety Commission standards, no bumpers, no loose bedding, and baby sleeping on their back.
Appointments & tests: looking ahead to glucose screening
Week 21 sits in a quiet stretch of pregnancy where most parents are between major milestones. You may not have an in-office visit this week — in uncomplicated pregnancies in the US, prenatal visits are typically about every four weeks through the second trimester. If you do have a visit, expect the standard routine: a check of your blood pressure, weight, and urine, a listen to your baby's heartbeat with a Doppler, and a measurement of your fundal height (the distance from the pubic bone to the top of the uterus). At week 21, that number should be around 19 to 23 centimeters.
The big screening on the horizon is the glucose challenge test for gestational diabetes, usually scheduled between weeks 24 and 28. Risk factors that sometimes lead to earlier screening include a higher pre-pregnancy BMI, a family history of type 2 diabetes, gestational diabetes in a previous pregnancy, a previous baby over 9 pounds, PCOS, or being over 35. The standard one-hour test involves drinking a sweet glucose drink at the clinic and having your blood drawn an hour later — no fasting needed. This is also a sensible week to think ahead about the Tdap vaccine (recommended in every pregnancy between weeks 27 and 36), the seasonal flu shot, RSV vaccination during the right window, and which childbirth or breastfeeding classes you would like to take. Good questions for your provider: when will I have my glucose screen and Tdap, is there any reason to test for diabetes earlier in my case, and has the placenta moved up if I had a low-lying placenta on my anatomy scan.
Call your provider if
- Regular, painful tightenings of the uterus, especially more than four in an hour (possible early signs of preterm labor), or low backache that comes in waves
- New, constant pelvic pressure that feels like something is bearing down
- A sudden gush or steady trickle of clear fluid from the vagina, or any vaginal bleeding beyond very light spotting
- A severe headache that does not ease, blurred vision or seeing spots, severe upper-belly pain on the right under your ribs, or sudden swelling of the face and hands (possible preeclampsia)
- A fever above 100.4°F, burning with urination, or a noticeable, sustained change in how your baby is moving once you have a sense of their pattern
Reflects Mayo Clinic and Cleveland Clinic second-trimester fetal-development references and Mayo Clinic fundal-height guidance, 2024–2026.
Related questions
- How big is the baby at 21 weeks pregnant?
- About the size of a large carrot — roughly 10.5 inches long and around 12 to 13 ounces (about 360 grams). Movements have become coordinated and frequent, eyebrows are sprouting, and the bone marrow has started making blood cells.
- What does baby movement feel like at 21 weeks?
- Many parents say week 21 is when the flutters they have been wondering about start to feel like definite movement — small thumps, taps, and pokes you would actually call kicks. The pattern is still irregular, so a quiet day with little movement is normal; a consistent daily routine usually emerges closer to weeks 24 to 28.
- Are varicose veins and leg cramps normal at 21 weeks?
- Yes. Your blood volume has climbed close to 50 percent above pre-pregnancy levels, and your growing uterus presses on the veins that carry blood back from your legs. That commonly causes varicose veins, hemorrhoids, and nighttime leg cramps. None are dangerous on their own, though they can be uncomfortable.
- When is the glucose screening for gestational diabetes?
- The glucose challenge test is usually scheduled between weeks 24 and 28. Some risk factors — a higher pre-pregnancy BMI, a family history of type 2 diabetes, gestational diabetes in a previous pregnancy, PCOS, or being over 35 — can lead to earlier screening, so week 21 is a good time to flag them with your provider.
Sources & further reading
ParentFlow: one free app, pregnancy to age six
ParentFlow follows your pregnancy week by week — baby size, what's developing, your symptoms, and the appointments and warning signs that matter — then becomes a free baby tracker for feeds, sleep, and growth after birth. Free on iPhone and Android.
App Store Google Play Open Web AppThis article reflects current ACOG, Mayo Clinic, Cleveland Clinic, CDC, and FDA guidance and is for educational purposes only. It does not constitute medical advice. ParentFlow is a wellness companion — not a substitute for your obstetric provider. For any medical concern, contact your healthcare provider.