A comprehensive guide to your baby’s growth throughout pregnancy, with fun fruit and vegetable comparisons to help you visualize their development.
First Trimester (Weeks 1-12)
Week 1
Baby’s Size: No baby yet! Your body is preparing for possible conception.
What’s Happening: Technically, this is the week of your last period before conception. Your body is getting ready for a potential pregnancy.
Fun Fact: Though there’s no baby yet, now is the perfect time to start taking prenatal vitamins with folic acid.
Week 2
Baby’s Size: Still no baby, but conception may happen soon!
What’s Happening: Your body is preparing to release an egg that could become your baby.
Good to Know: Focus on a nutrient-rich diet with plenty of fruits, vegetables, and whole grains to create an optimal environment for conception.
Week 3
Baby’s Size: 🌱 Poppy seed (0.004 inches)
What’s Happening: Fertilization has likely occurred! Your fertilized egg (also called a zygote) is dividing rapidly as it travels toward your uterus.
Development Highlight: The fertilized egg contains all the genetic information that will determine your baby’s traits.
Week 4
Baby’s Size: 🌱 Mustard seed (0.014 inches)
What’s Happening: The fertilized egg has reached your uterus and is implanting in the uterine lining.
Development Highlight: This tiny cluster of cells will eventually develop into your baby and the placenta that will nourish them.
Week 5
Baby’s Size: 🌱 Sesame seed (0.05-0.1 inches)
What’s Happening: Your embryo now has three distinct layers of cells that will develop into different body systems.
Development Highlight: The neural tube, which will become your baby’s brain and spinal cord, is beginning to form.
Week 6
Baby’s Size: 🌱 Lentil seed (0.16-0.2 inches)
What’s Happening: A primitive heartbeat may be detectable via ultrasound!
Development Highlight: The neural tube is forming, and your baby’s heart begins to beat around 105 times per minute.
Week 7
Baby’s Size: 🫐 Blueberry (0.3 inches)
What’s Happening: Your baby is growing rapidly, with arm and leg buds appearing.
Development Highlight: The head is developing quickly, with facial features beginning to form. Your baby’s brain cells are multiplying at an astonishing rate!
Week 8
Baby’s Size: 🍓 Raspberry (0.6 inches)
What’s Happening: Tiny fingers and toes are forming, though they’re still webbed.
Development Highlight: All essential organs have begun to develop. Your baby’s heart has divided into chambers and is beating at about 150 beats per minute.
Week 9
Baby’s Size: 🍇 Grape (0.9 inches)
What’s Happening: The embryo is now officially a fetus!
Development Highlight: Your baby has more distinct facial features and developing ears. The tiny tail that all embryos develop is disappearing.
Week 10
Baby’s Size: 🍊 Kumquat (1.2 inches)
Weight: 0.14 ounces (4 grams)
What’s Happening: Vital organs are functioning, and cartilage is beginning to form into bones.
Development Highlight: Your baby can now move their limbs, though you won’t feel it for several more weeks.
Read more: Week-by-Week Pregnancy Tips: Your Complete Pregnancy Timeline
Week 11
Baby’s Size: 🍋 Fig (1.6 inches)
Weight: 0.25 ounces (7 grams)
What’s Happening: Your baby is moving around, though you likely can’t feel it yet.
Development Highlight: The head makes up about half of your baby’s body length, but the body will soon catch up in proportion.
Week 12
Baby’s Size: 🍈 Lime (2.1 inches)
Weight: 0.49 ounces (14 grams)
What’s Happening: The digestive system is beginning to practice, and reflexes are developing.
Development Highlight: Your baby can now make a fist, and their brain is developing at an astonishing rate.
Second Trimester (Weeks 13-27)
Week 13
Baby’s Size: 🍑 Plum (2.9 inches)
Weight: 0.81 ounces (23 grams)
What’s Happening: Your baby’s fingerprints are forming, making them truly one-of-a-kind!
Development Highlight: The vocal cords are developing, preparing for those first cries (and later, conversations!).
Week 14
Baby’s Size: 🍋 Lemon (3.4 inches)
Weight: 1.5 ounces (43 grams)
What’s Happening: The baby’s facial muscles are developing, allowing for expressions like squinting and frowning.
Development Highlight: Your baby can now make facial expressions, even practicing frowning and squinting!
Week 15
Baby’s Size: 🍊 Navel orange (4 inches)
Weight: 2.5 ounces (70 grams)
What’s Happening: The skeleton is developing rapidly, and the baby may begin to develop a sucking reflex.
Development Highlight: Your baby’s bones are becoming harder, though they remain flexible for delivery.
Week 16
Baby’s Size: 🥑 Avocado (4.6 inches)
Weight: 3.5 ounces (100 grams)
What’s Happening: The baby’s eyes are becoming sensitive to light, and the tiny ears can now detect sounds.
Development Highlight: Your baby might be able to hear your voice now! Talk, read, or sing to your little one.
Week 17
Baby’s Size: 🍐 Pear (5.1 inches)
Weight: 5.3 ounces (150 grams)
What’s Happening: The baby’s skeleton is changing from cartilage to bone, and sweat glands are developing.
Development Highlight: Your baby is storing energy in the form of fat and practicing using their growing muscles.
Week 18
Baby’s Size: 🫑 Bell pepper (5.6 inches)
Weight: 7 ounces (200 grams)
What’s Happening: The baby can now yawn and hiccup, and you might begin to feel movements!
Development Highlight: This is often when first-time moms begin to feel those exciting first flutters of movement.
Week 19
Baby’s Size: 🍅 Tomato (6 inches)
Weight: 8.5 ounces (240 grams)
What’s Happening: A protective coating called vernix caseosa begins to cover the baby’s skin.
Development Highlight: This waxy coating protects your baby’s skin from the amniotic fluid and will be visible at birth.
Read more: Mom’s Body Week by Week: Your Changing Shape Throughout Pregnancy
Week 20
Baby’s Size: 🍌 Banana (6.5 inches)
Weight: 10.6 ounces (300 grams)
What’s Happening: This is the halfway point of pregnancy!
Development Highlight: Your baby’s permanent teeth are developing beneath the gums, and you might be able to find out the sex at your ultrasound.
Week 21
Baby’s Size: 🥕 Carrot (7.2 inches)
Weight: 12.7 ounces (360 grams)
What’s Happening: The baby is increasingly active and can now swallow amniotic fluid.
Development Highlight: Your baby’s taste buds are developing, and they can taste the flavors that pass through the amniotic fluid.
Week 22
Baby’s Size: 🍝 Spaghetti squash (7.6 inches)
Weight: 15.2 ounces (430 grams)
What’s Happening: The baby’s eyebrows and eyelids are fully formed, and fingernails have developed.
Development Highlight: Your baby now has a regular schedule of sleeping and waking, though it might not match yours!
Week 23
Baby’s Size: 🥭 Large mango (8 inches)
Weight: 1.1 pounds (500 grams)
What’s Happening: The baby’s inner ear is developed enough to provide a sense of balance.
Development Highlight: Your baby can now distinguish between up and down, which will be important for birth positioning later.
Week 24
Baby’s Size: 🌽 Ear of corn (8.3 inches)
Weight: 1.3 pounds (600 grams)
What’s Happening: The baby’s lungs are developing rapidly, preparing for breathing.
Development Highlight: While not yet viable, babies born at this stage have a chance of survival with intensive medical care.
Week 25
Baby’s Size: 🥔 Turnip (8.8 inches)
Weight: 1.5 pounds (700 grams)
What’s Happening: The baby is practicing breathing by inhaling amniotic fluid into developing lungs.
Development Highlight: Your baby’s movements might become more noticeable to others now if they place a hand on your belly.
Week 26
Baby’s Size: 🧅 Scallion (9.2 inches)
Weight: 1.7 pounds (760 grams)
What’s Happening: The baby’s eyes are fully formed and beginning to open and close.
Development Highlight: Your baby’s eyes have developed, though they’ll likely change color after birth.
Week 27
Baby’s Size: 🥦 Cauliflower (9.6 inches)
Weight: 1.9 pounds (875 grams)
What’s Happening: The baby can now recognize familiar voices and may respond to them.
Development Highlight: Your baby might respond to your voice by moving or changing their heart rate—keep talking!
Third Trimester (Weeks 28-40+)
Week 28
Baby’s Size: 🍆 Large eggplant (10 inches)
Weight: 2.2 pounds (1000 grams)
What’s Happening: The baby’s brain is developing rapidly, with billions of neurons forming.
Development Highlight: Your baby can blink and has eyelashes. Their brain waves show patterns similar to those of a newborn.
Week 29
Baby’s Size: 🎃 Butternut squash (10.5 inches)
Weight: 2.5 pounds (1150 grams)
What’s Happening: The baby is putting on weight rapidly, with more fat accumulating under the skin.
Development Highlight: This extra fat will help regulate body temperature after birth.
Week 30
Baby’s Size: 🥬 Cabbage (10.9 inches)
Weight: 2.9 pounds (1300 grams)
What’s Happening: The baby’s brain can control body temperature and has regular sleep-wake cycles.
Development Highlight: Your baby now has definite sleeping and waking patterns, and you might notice them being more active at certain times of day.
Week 31
Baby’s Size: 🥥 Coconut (11.2 inches)
Weight: 3.3 pounds (1500 grams)
What’s Happening: The baby’s immune system is developing, receiving antibodies from you.
Development Highlight: These antibodies will help protect your newborn from illness during the first few months of life.
Week 32
Baby’s Size: 🥭 Jicama (11.5 inches)
Weight: 3.75 pounds (1700 grams)
What’s Happening: The baby’s bones are fully formed, though still soft and pliable.
Development Highlight: Your baby’s bones will remain somewhat flexible to ease the journey through the birth canal.
Week 33
Baby’s Size: 🍍 Pineapple (12 inches)
Weight: 4.2 pounds (1900 grams)
What’s Happening: The baby’s lungs are nearly mature, and they’re rapidly gaining weight.
Development Highlight: Your baby is putting on about half a pound a week from now until birth!
Week 34
Baby’s Size: 🍈 Cantaloupe (12.6 inches)
Weight: 4.7 pounds (2150 grams)
What’s Happening: The baby’s central nervous system is maturing, and fingernails reach the fingertips.
Development Highlight: Your baby is preparing for life outside the womb, with functioning kidneys and a strong immune system.
Week 35
Baby’s Size: 🍈 Honeydew melon (13 inches)
Weight: 5.25 pounds (2400 grams)
What’s Happening: The baby’s kidneys are fully developed, and the liver can process some waste.
Development Highlight: Your baby is now considered “early term” and would likely require minimal medical intervention if born now.
Week 36
Baby’s Size: 🥬 Romaine lettuce (13.6 inches)
Weight: 5.75 pounds (2600 grams)
What’s Happening: The baby is considered early term, with most systems ready for life outside the womb.
Development Highlight: Your baby has likely settled into the head-down position in preparation for birth.
Week 37
Baby’s Size: 🥬 Swiss chard (14 inches)
Weight: 6.3 pounds (2850 grams)
What’s Happening: The baby is continuing to gain weight and is likely in a head-down position.
Development Highlight: Your baby is officially considered “early term” and is practicing important skills like breathing and sucking.
Week 38
Baby’s Size: 🧅 Leek (14.8 inches)
Weight: 6.8 pounds (3100 grams)
What’s Happening: The baby’s brain and lungs continue to develop in preparation for birth.
Development Highlight: Your baby’s organs are ready for life outside the womb, and he or she continues to build fat stores for temperature regulation.
Week 39
Baby’s Size: 🎃 Pumpkin (15.2 inches)
Weight: 7.25 pounds (3300 grams)
What’s Happening: The baby has developed a firm grasp and is building up immunities.
Development Highlight: Your baby is considered full term and could arrive any day now!
Week 40
Baby’s Size: 🍉 Watermelon (15.7 inches)
Weight: 7.6 pounds (3460 grams)
What’s Happening: This is your due date, though only about 5% of babies arrive exactly on time.
Development Highlight: Your baby is fully developed and ready to meet you!
Read more: Fetal Development Week by Week: Your Complete Pregnancy Timeline
Week 41
Baby’s Size: 🍈 Jackfruit (16 inches)
Weight: 8 pounds (3630 grams)
What’s Happening: The baby continues to build fat stores and develop brain connections.
Development Highlight: Your baby is now considered late-term, but is still perfectly healthy and continuing to develop inside.
Week 42
Baby’s Size: 🍉 Large watermelon (16.5 inches)
Weight: 8.3 pounds (3760 grams)
What’s Happening: You’re now considered post-term, and your healthcare provider will monitor you closely.
Development Highlight: Your baby is fully developed and will likely arrive very soon, either naturally or with some medical assistance.
Key Pregnancy Milestones
- First Trimester (Weeks 1-12): From conception to basic organ development
- Second Trimester (Weeks 13-27): Major growth and development of features and functionality
- Third Trimester (Weeks 28-40+): Final preparation for birth with significant weight gain
Remember that every pregnancy is unique, and these measurements are averages. Your baby may be slightly larger or smaller than these examples, which is perfectly normal.