Week 21
Your baby is the size of a carrot
What's happening this week
Your baby is now the size of a carrot — about 10.5 inches from head to toe and weighing around 12 to 13 ounces. The growth from here on is less about building new structures and more about refining and strengthening what's already in place.
Eyebrows are now visible — thin and delicate, but there. Hair on the scalp is also growing, though color and texture may change significantly between now and birth (and even after). Your baby is completely covered in lanugo, the fine downy hair that helps regulate temperature and holds the protective vernix caseosa against the skin.
Your baby's taste buds are now functional, and they can taste the amniotic fluid they swallow. Research suggests that the flavors of what you eat — garlic, ginger, vanilla, and other strong flavors — make their way into the amniotic fluid, and your baby may develop preferences based on these early exposures. So that curry you had for dinner? Your baby tried it too.
The sucking reflex is developing rapidly. On ultrasound, babies at this stage are frequently caught sucking their thumbs — practicing the skill they'll need for feeding after birth. Your baby also has clear sleep-wake cycles now, and you may notice that their most active periods correspond to times when you're resting.
Bone marrow has fully taken over blood cell production, a job previously shared between the liver and spleen. The marrow is now the primary factory for red blood cells, white blood cells, and platelets — just as it will be for the rest of your baby's life.
Your body this week
By week 21, you're solidly in the second trimester groove. Many people feel good at this point — energy is up, the bump is visible but manageable, and you're likely feeling regular baby movements that make the whole experience feel more connected and real.
Your uterus now extends above your belly button, and your provider is measuring your fundal height at each visit. At 21 weeks, the fundal height should be approximately 21 centimeters, give or take. This measurement is a quick check on your baby's growth between ultrasounds.
You might be noticing some new or intensifying symptoms: varicose veins (caused by increased blood volume and the pressure of your uterus on major veins), spider veins on your legs or face, and occasional leg cramps — especially at night. Staying hydrated, stretching your calves before bed, and elevating your legs when possible can all help.
Breast changes continue: your breasts may be noticeably larger, and some people begin producing colostrum (early breast milk) as early as the second trimester. Don't be alarmed if you notice small amounts of yellowish discharge — this is normal and is a sign that your body is preparing for breastfeeding.
If you had your anatomy scan recently, you may be processing the results. For the vast majority of pregnancies, the scan confirms that everything is developing normally. If your provider flagged anything that needs follow-up, ask for clear explanations and don't hesitate to seek a second opinion if you feel uncertain.
For dads
If the anatomy scan results are in, you may now know your baby's sex — or you may have chosen to keep it a surprise. Either way, the level of detail from that scan likely made the pregnancy feel more vivid and real for you. You've seen the brain, the heart, the tiny fingers and toes. That image might be sitting on your phone right now, and you might find yourself looking at it more than you expected. This is a good time to start baby-proofing your thinking about finances and logistics. If you haven't discussed parental leave with your employer, now is the time. Review your health insurance plan to understand what's covered for delivery and newborn care. These conversations are better had at 21 weeks than at 38 weeks.
Your partner's body is changing rapidly, and she may have mixed feelings about it. She might love the bump and feel powerful, or she might miss her pre-pregnancy body and feel frustrated by the physical limitations. Both reactions are normal, and they can coexist — sometimes in the same hour. Your job isn't to have an opinion about her body. Your job is to make her feel loved and attractive regardless. Specific compliments work better than generic ones: 'Your smile is incredible today' lands better than 'you look fine.' And if she wants to vent about feeling uncomfortable, listen without trying to solve it.
Common concerns
Is it normal to have vivid or strange dreams during pregnancy?+
Yes — pregnancy dreams are notoriously vivid, strange, and sometimes disturbing. This is caused by a combination of hormonal changes, disrupted sleep patterns (you're more likely to wake during REM sleep), and the emotional processing that comes with a major life change. Common themes include dreams about the baby, birth, or anxiety about parenthood. They're normal and don't predict anything about your pregnancy or your future as a parent.
What causes leg cramps during pregnancy?+
Leg cramps — especially at night — are common in the second and third trimesters. The exact cause isn't fully understood, but contributing factors include increased blood volume, extra weight on your legs, compression of blood vessels by the growing uterus, and possibly mineral imbalances (calcium and magnesium). Staying hydrated, stretching your calves before bed, and gentle daily exercise can help. If cramps are severe or persistent, mention them to your provider.
Is it normal to feel the baby move more at night?+
Very common. During the day, your movement tends to rock the baby to sleep. When you lie down and get still in the evening or at bedtime, your baby may wake up and become more active. Some parents also report that eating or drinking something cold triggers movement. These patterns will become more pronounced as the pregnancy progresses and are a normal part of your baby's developing sleep-wake cycle.
When should I start a birth plan?+
There's no perfect time, but the second trimester is a good window to start thinking about your preferences. A birth plan isn't a rigid contract — it's a communication tool that helps your healthcare team understand your wishes. Consider topics like pain management preferences, who you want in the room, preferences about interventions, and immediate postpartum wishes (skin-to-skin, delayed cord clamping). Childbirth education classes can help inform these decisions. Your plan can evolve as you learn more.
Product picks for week 21
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Maternity support belt
As your belly grows, a support belt can ease lower back pressure and make standing and walking more comfortable.
Leg cramp relief magnesium spray
Pregnancy leg cramps are common at night — a topical magnesium spray may help ease cramping and improve sleep.
Gender reveal supplies or keepsake box
If you just found out the sex, a small celebration or keepsake box marks this special moment in your journey.
A quick note: This content is for informational purposes only and is not a substitute for professional medical advice. Always talk to your healthcare provider about any questions or concerns. Learn how we create our content.
Content based on guidance from the American College of Obstetricians and Gynecologists (ACOG), the American Academy of Pediatrics (AAP), Mayo Clinic, and peer-reviewed medical literature. Learn more about how we create our content.