Pregnancy Week by Week
21 Weeks Pregnant
At 21 weeks pregnant, baby is the size of a carrot (~26.7 cm, 360 g). Discover taste bud development, stronger kicks, varicose veins, and rising appetite.
Published:
This article is for general information and is not a substitute for professional medical advice. Always consult your pediatrician or doctor about your child.
Sources: WHO, CDC, AAP and NHS guidance. Recommendations differ between countries — for local advice see the NHS or ACOG.
See how we research and review →
At a Glance: Week 21
- Trimester: Second trimester
- Baby's size: About the size of a carrot — roughly 26.7 cm (10.5 inches) crown to heel and approximately 360 g (12.7 oz). Measurement is now taken head-to-heel.
- Key milestone: Taste buds are functional, movement is becoming stronger and more coordinated, and the bone marrow has begun producing blood cells (taking over from the liver and spleen). Your baby may now sleep and wake in detectable cycles.
Your Baby's Development This Week
Week 21 marks a transition from foundation-building to active maturation. Organs are formed; now they are refining function. Your baby is becoming a busier, more responsive little person.
- Taste buds: Functional taste buds detect flavor compounds in the amniotic fluid. Exposure to varied flavors may influence later food preferences.
- Digestive practice: Your baby swallows small amounts of amniotic fluid, which the developing digestive tract absorbs. Tiny amounts of sugar and nutrients are processed by the gut.
- Bone marrow: Blood cell production shifts from the liver and spleen to the bone marrow, a major maturation step for the immune and circulatory systems.
- Movement coordination: Movements are stronger and more purposeful — somersaults, stretches, punches, kicks, hand-to-face exploration, even thumb sucking.
- Sleep-wake cycles: Distinct active and quiet periods, often lasting 20 to 40 minutes each, become detectable.
- Eyelids and eyebrows: Eyelids are fully formed though still fused; eyebrows and eyelashes are visible.
- Reproductive system: In females, the vagina is beginning to canalize. In males, the testes remain in the abdomen but are preparing to descend in the coming weeks.
Your Body and Symptoms This Week
By 21 weeks, your fundus is roughly 1 cm above the belly button. Many people are now comfortably "pregnant-looking" rather than ambiguously rounded. Symptoms continue to evolve as circulation, hormone levels, and biomechanics shift.
- Increased appetite: Hunger rises as your baby grows rapidly and the early-pregnancy nausea is well behind you.
- Varicose veins and hemorrhoids: Increased blood volume, vein wall relaxation, and uterine pressure on pelvic veins set the stage for varicose veins in legs, vulva, or anus (hemorrhoids).
- Leg cramps: Continue to be common, especially at night.
- Mild swelling: Of the ankles and feet, especially at the end of the day or in warm weather.
- Visible kicks: A noticeable bump or twitch on the surface of the belly during an active fetal period.
- Breast changes: Areolas continue to darken; small bumps (Montgomery glands) become more visible. Some people see early colostrum drops.
- Back, hip, and pelvic pain: Shifting center of gravity and joint laxity from relaxin contribute to musculoskeletal aches.
- Forgetfulness or "pregnancy brain": Mild cognitive shifts are common, harmless, and reverse postpartum.
Nutrition: What to Eat and Avoid This Week
Iron and calcium needs remain elevated. Your blood volume is roughly 40% higher than pre-pregnancy by this point, and iron supports the production of additional red blood cells. Adequate hydration becomes especially important to reduce constipation, cramping, and Braxton Hicks intensity.
Prioritize:
- Iron sources: Lean red meat, poultry, lentils, beans, tofu, fortified cereals. Pair plant-based iron with vitamin C foods for better absorption.
- Calcium sources: Yogurt, milk, fortified plant beverages, leafy greens, sardines, calcium-set tofu.
- Protein: Aim for about 75 to 100 g per day to support fetal tissue growth.
- Variety of flavors: Since taste buds are active, eating a colorful, diverse diet (herbs, spices, vegetables, fruits) introduces flavor experience.
- Water: At least 10 cups per day to support increased blood volume and reduce constipation, hemorrhoid risk, and Braxton Hicks.
- Fiber: Whole grains, fruits, vegetables, legumes — 25 to 30 g per day.
Continue to avoid: alcohol, high-mercury fish, raw or undercooked meat/fish/eggs, unpasteurized dairy and juice, unheated deli meats. Keep caffeine under 200 mg/day. Limit added sugars and ultra-processed foods, especially with the gestational diabetes screen approaching.
Movement and Exercise
Continued regular activity is one of the strongest, evidence-based pregnancy interventions — it reduces the risk of gestational diabetes, excessive weight gain, hypertensive disorders, and improves mood and sleep. ACOG recommends 150 minutes per week of moderate activity for low-risk pregnancies.
Best activities at 21 weeks: walking, swimming or aqua aerobics (especially helpful for back pain and swelling), stationary cycling, prenatal yoga or Pilates, light to moderate strength training, and dedicated pelvic floor work.
Avoid or modify: prolonged flat-on-back positions, exercises that involve heavy Valsalva straining, deep twists, contact sports, hot yoga or environments above 39°C/102°F core temp, and any activity with significant fall risk. If you have not been exercising, start gently and build up; talk to your provider first.
Mental and Emotional Wellbeing
Many people describe the early-to-mid second trimester as the emotional sweet spot of pregnancy — energy is back, the anatomy scan has often offered reassurance, and the baby's movements feel like a daily form of connection. That said, mood swings, anxiety about labor, and body-image worries are common.
Sleep: Becoming trickier as comfortable positions shrink. A full-body pregnancy pillow is a worthwhile investment this week.
Mood: If you notice persistent sadness, intense worry, intrusive thoughts, or loss of interest, contact your provider. Perinatal mental health treatment is safe and effective.
Partner connection: Strong outside kicks make this a wonderful time to invite partners and older siblings to "meet" the baby through touch.
Common Concerns and When to Call Your Doctor
Contact your provider promptly if you experience:
- Vaginal bleeding of any amount
- Leaking fluid (gush or steady drip)
- Regular tightening — more than 4 in an hour before 37 weeks
- Severe abdominal or pelvic pain
- Severe persistent headache, blurred vision, or sudden facial/hand swelling (possible preeclampsia, although typically later)
- One-sided leg pain, swelling, redness, or warmth (possible blood clot)
- Painful urination or fever
- A red, hot, painful varicose vein
- A clear, sustained drop in movement compared to your recent baseline
Tests and Appointments This Week
For most low-risk pregnancies, week 21 doesn't include scheduled testing. You may have a routine prenatal visit with weight, blood pressure, urine dip, fundal height, and fetal heart-rate check. If your anatomy scan revealed any items that need follow-up (placental position, soft markers, growth), your provider may have scheduled a repeat ultrasound. Coming up: the glucose challenge test for gestational diabetes screening between 24 and 28 weeks.
Tips for Week 21
- Get fitted for a maternity bra. Breasts may have grown 1 to 2 cup sizes; proper support reduces back and shoulder strain.
- Use compression stockings. Even mild graduated compression can prevent or reduce varicose veins and ankle swelling.
- Sign up for a childbirth class now. Many fill up; classes are typically taken between weeks 28 and 36.
- Hydrate and walk hourly. Especially if you sit at a desk — circulation in the lower body benefits enormously from short, frequent movement breaks.
- Eat varied flavors. Your baby's taste buds are sampling — give them an interesting culinary experience.
Preparing for What's Next
With the halfway point behind you, the next major milestone is the gestational diabetes screen (24 to 28 weeks). This is also a great time to start serious nursery planning, baby registries, and choosing a pediatrician (most are happy to do a prenatal meet-and-greet). If you plan to breastfeed, consider starting a beginner's class around weeks 24 to 30. And if you'll need childcare after parental leave, begin researching now — waitlists at many centers run 6 to 12 months long.
Frequently Asked Questions About Week 21
Why have my baby's movements suddenly become stronger at 21 weeks?
Around week 21, your baby has grown enough — and your abdominal wall has stretched enough — that movements are noticeably stronger and more frequent. The flutters of weeks 18 to 20 begin to turn into clearer kicks, rolls, and even hiccup rhythms. Your baby is also more muscularly developed and has more space to push against the uterine wall. Many partners can feel an outside kick for the first time around now if they place a hand on the lower belly during an active period.
Why am I suddenly so hungry at 21 weeks pregnant?
By the start of the second-half of pregnancy, your calorie needs increase by about 340 extra calories per day, and your baby's growth rate accelerates. Many people experience a surge in appetite around weeks 20 to 22, especially after the appetite suppression of early pregnancy nausea. Listen to hunger cues, but emphasize nutrient density: protein at every meal, complex carbs, healthy fats, fruits, and vegetables. A few smaller, well-balanced meals throughout the day work better than three large ones and help with heartburn too.
Is it normal to have varicose veins this early in pregnancy?
Yes. Increased blood volume, hormonal relaxation of vein walls, and pressure from the growing uterus on the inferior vena cava can lead to varicose veins on the legs or vulva starting around weeks 20 to 24. They often improve significantly after delivery. Wear graduated compression stockings, avoid prolonged standing or sitting, elevate your legs when possible, and stay active. If a vein becomes red, hot, painful, or develops a hard knot, contact your provider — this could signal a clot.
Can my baby taste what I eat at 21 weeks?
Yes, in a limited way. Taste buds are now present on the tongue and palate, and flavor compounds from your diet pass into the amniotic fluid that your baby is regularly swallowing. Research suggests that exposure to a variety of flavors in utero can influence later food preferences. This is a nice scientific reason to eat a varied, colorful diet of vegetables, fruits, herbs, and spices.
When should I worry about swelling at 21 weeks pregnant?
Mild swelling of the feet and ankles by the end of the day is common in the second half of pregnancy, especially in hot weather or after standing. Sudden swelling of the hands, face, or one leg, particularly if accompanied by severe headache, vision changes, or upper-right abdominal pain, can suggest preeclampsia or a blood clot and requires urgent evaluation. Call your provider promptly for any of these warning signs.
Are stretch marks at 21 weeks preventable?
Stretch marks (striae gravidarum) are largely genetically determined and develop when rapidly stretching skin damages the underlying connective tissue. Moisturizing creams may improve comfort and appearance but no topical product has been proven to prevent stretch marks. Stay well hydrated, gain weight at a steady pace, and accept that they fade significantly after delivery — most pregnancy stretch marks go from red or purple to a faint silvery line over 6 to 12 months postpartum.
Is it normal to feel hiccup-like rhythmic movements at 21 weeks?
Yes — fetal hiccups are common and harmless from about week 20 onward. They feel like small, rhythmic taps at the same spot for several minutes at a time. Hiccups occur because your baby is practicing diaphragmatic movement, an important rehearsal for breathing after birth. They can happen multiple times a day. As long as they are accompanied by normal movement otherwise, there is nothing to worry about.
Can I travel by plane at 21 weeks pregnant?
For uncomplicated pregnancies, ACOG considers air travel safe up to about 36 weeks. The second trimester is generally the most comfortable time to fly. Walk the aisle every hour or two, stay hydrated, wear compression socks to reduce clot risk, and keep your seatbelt low across the hips. Check with your provider before flying if you have a high-risk pregnancy, and confirm the airline's late-pregnancy policies.
Should I be doing kick counts at 21 weeks?
Formal kick counts (such as the "count to 10" method) typically begin around 28 weeks, when movement becomes consistent and predictable. At 21 weeks, movements are still irregular and easily missed, so structured counting isn't reliable yet. Pay attention to general patterns and contact your provider if you have noticed a clear, sustained drop in movement compared to your baby's recent baseline.
Why is my lower back so much more painful this week?
By 21 weeks, the uterus has risen well above the belly button, shifting your center of gravity forward. To compensate, the lower back curves more (lumbar lordosis), straining the muscles and joints there. Relaxin loosens the sacroiliac joints, which can add a deep ache. Try prenatal yoga, swimming, supportive footwear, sleeping with a pillow between the knees, and a maternity support belt for daytime relief. Persistent severe back pain, especially with fever or painful urination, should be evaluated.
Track Your Pregnancy Week by Week with Whispie
Personalized weekly updates, symptom tracking, and evidence-based guidance from your first trimester through delivery.
Weekly parenting tips, no spam
Evidence-based guidance for your child's stage — straight to your inbox.