Week 21 of Pregnancy
Your baby’s heart is now beating and may be detectable on an early ultrasound. Tiny buds that will become arms and legs are beginning to form, and hormone levels are rising quickly, which means symptoms like nausea, fatigue, and mood swings may be more intense this week
Baby’s Size
Your baby is about the size of a carrot.
Baby’s Development at 21 weeks
More Noticeable Movement Patterns
Your baby is now more active and you may begin to recognize a pattern, like increased movement at night when you're resting.
The digestive system is developing steadily as your baby swallows amniotic fluid, which helps prepare the gastrointestinal tract for feeding after birth.
Maturing Digestive System
Bone Marrow Begins Making Blood Cells
Your baby’s bone marrow is starting to produce blood cells, gradually taking over this role from the liver and spleen.
Developing Taste Buds and Sensing Flavours
Taste buds are forming, and your baby may start detecting strong flavors in the amniotic fluid, depending on what you eat.
Pregnancy Symptoms during Week 21
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As your belly grows and your center of gravity shifts, your lower back may start to feel the strain. Your posture naturally adjusts to support the extra weight, which can lead to aches and discomfort in the back and hips. Gentle stretching, supportive shoes, and a pregnancy pillow at night may help ease this discomfort.
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You may notice a rise in clear or white vaginal discharge, known as leukorrhea. This is your body’s natural way of preventing infections and keeping the birth canal clean. It’s completely normal unless it becomes yellow, green, has a foul odor, or causes itching or burning, in which case you should contact your healthcare provider.
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Skin changes are common during pregnancy due to hormonal shifts. You might notice your areolas becoming darker, or see a faint or pronounced dark vertical line—called the linea nigra—running down your abdomen. These changes are harmless and tend to fade after birth, though every body responds a little differently.
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Around this time, some people begin feeling Braxton Hicks contractions. These are irregular, usually painless tightening sensations in your abdomen. They are your uterus’s way of preparing for labor. Staying hydrated and changing positions can sometimes ease them, but if they become painful or regular, contact your provider.
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Emotions may feel more intense or harder to manage right now. Hormonal changes can lead to mood swings, increased anxiety, or even moments of unexpected joy or sadness. Be kind to yourself and know that these emotional fluctuations are a natural part of pregnancy. Talking to a partner, friend, or counselor can also help.
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Leg cramps—often striking at night—may become more frequent in the second trimester. These sudden, painful spasms can be caused by changes in circulation, pressure on nerves, or low levels of key minerals like magnesium or calcium. Stretching before bed, staying well-hydrated, and using warm compresses can provide relief.
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As your skin stretches to accommodate your growing baby, you may start to see reddish or purple streaks on your abdomen, breasts, thighs, or hips. These are stretch marks and are incredibly common. While there’s no proven way to prevent them entirely, moisturizing regularly can help keep your skin supple and reduce itchiness.
Pregnancy checklist at 21 weeks pregnant
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If you haven’t already, try sleeping on your side—especially your left side. This position improves circulation to your baby and reduces pressure on major blood vessels, helping prevent swelling and back pain. Use pillows behind your back and between your knees for better support and comfort through the night.
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Review your prenatal vitamin routine with your provider to make sure you're getting enough iron and calcium. These nutrients are especially important now for your baby’s bone growth and your increasing blood volume. A quick check-in ensures your supplement plan is still the best fit.
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As your belly and breasts grow, you might notice your skin feels itchy or tight. Apply a gentle moisturizer daily to help with skin elasticity and reduce discomfort. It’s also a soothing way to connect with your changing body.
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Begin looking into pediatricians in your area. Ask for recommendations, read reviews, and make a shortlist of providers who align with your preferences. Preparing early helps reduce stress later and gives you time to ask important questions before baby arrives.
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Take weekly bump photos or write short journal entries about how you're feeling. These little moments help you reflect, stay present, and build a keepsake you’ll treasure in the future. It’s also a beautiful way to bond with your baby.
21 Weeks Pregnant Belly
By Week 21, your belly is visibly rounded and growing steadily as your uterus continues to expand above your belly button. You may notice your belly button beginning to flatten or pop out. As your center of gravity shifts, maintaining good posture becomes more important to reduce strain on your lower back.
Tips & Resources
Use a pregnancy support belt if you're experiencing round ligament pain or backaches.
Practice gentle prenatal yoga or stretching to reduce muscle tension and improve circulation.
Stay hydrated throughout the day—aim for 8–10 glasses of water daily.
Download our Free Guide: Third Trimester Tip Sheet to get ahead on what’s coming next.
Check out our Free Handout: Labor & Delivery Terminology Handout to start getting familiar with common birth terms.