How Big Is Your Baby?
A Week-By-Week Look at Baby’s Size and Development
Congratulations, you’re pregnant! The next nine months are truly a miraculous and magical journey where you get to watch your baby grow bigger and bigger every week. We here at Organic Valley thought it would be fun to show you your baby’s growth and milestones each week and relate them to some of our favorite food, farm animals, and Organic Valley products.
Weeks 1-4: Baby is the size of a sesame seed.
During weeks one to four, your baby is called an embryo and their cells will divide and grow rapidly to form a fetus or tiny little baby.
Week 5: Baby is the size of a small sunflower seed.
You likely just found out (or will soon!) that you’re pregnant—congratulations! Your tiny embryo is busy developing your baby's brain, heart, lungs, digestive tract, and more. It’s time to start focusing on a healthy whole foods diet to grow a healthy and happy baby.
Week 6: Baby is the size of a lentil.
Your baby’s little feet and hands are almost fully developed already. Ready, set, here you go!
Week 7: Baby is the size of a wild blueberry.
They’re growing fast, almost doubling in size now from week to week.
Week 8: Baby is the size of a garbanzo bean.
Your baby’s movements are now visible on an ultrasound, but you likely won’t feel them move until closer to 16 to 24 weeks.
Week 9: Baby is the size of a scoop of smoothie mix.
Your baby weighs a bit less than 1 ounce—the weight of a scoop of Prenatal or Postnatal Support Smoothie Mixes. These mixes are packed with organic nutrition for expecting and new mamas like you. Plus, not only do our smoothies deliver high-quality protein and other important key nutrients, your purchase supports small family farms and a higher standard of animal care.
Week 10: Baby is the size of a strawberry.
At week 10 your baby is about 1.2 inches long. It’s really important to eat enough vitamin A-rich foods when you’re pregnant to help develop your baby’s eyes, ears, heart, limbs, and immune system. Some of the best sources of vitamin A include full-fat dairy and eggs.
Week 11: Baby is the size of a big Brussels sprout.
By this week your baby has ears and a little tongue. What do you think they’ll like more someday ... plain or chocolate milk?
Week 12: Baby is the size of a plum.
This is the last week of your first trimester! All of your baby’s vital organs are fully formed now.
Week 13: Baby is the size of a chicken egg.
Good news for you and your baby chick—it’s the second trimester! Women who have been battling morning sickness will often see symptoms resolve by the beginning of the second trimester. If you need help managing any unwanted symptoms, notify your birth provider and consider working with a pregnancy dietitian for food-related relief.
Week 14: Baby is the size of a small onion.
The sex of your baby should be detectable on an ultrasound at this time. What’s your guess—boy or girl?
Week 15: Baby is the size of a small peach.
Speaking of peaches, your baby is growing peach fuzz on their body called lanugo that helps them stay warm and maintain their body temperature.
Week 16: Baby is the size of an avocado.
Around 16 weeks, you may start to feel your baby kick. Women often report feeling movements anywhere from 16-22 weeks. This is called quickening and some moms report it feels like a little flutter or tiny bubbles.
Week 17: Baby is the size of a Stringles.
Your baby is about 5 inches long and starting to put on body fat this week. This makes them about the same length as Organic Valley Stringles string cheese.
Week 18: Baby is the size of a block of Organic Valley Cheddar Cheese.
At this stage, your baby is measuring on average around 8 ½ inches long from head to bottom and weighs about 8 ounces.
Week 19: Baby is the size of a large beefsteak tomato.
A white creamy fluid called vernix is forming on your baby’s skin this week. It looks like lotion and they may be born with it. It’s totally normal and serves the purpose of protecting and moisturizing your baby’s skin.
Week 20: Baby is the size of an artichoke.
You’re halfway there—congrats! At your next appointment, or somewhere around 20 weeks, your birth provider will perform the fetal anatomic ultrasound. This is where you get to see your baby moving around and your technician will measure for growth and development milestones.
Week 21: Baby is the size of a carrot.
Now that you’re in the second half of your pregnancy, you’re likely showing a little baby bump. Keep up the good work and continue to focus on a diet rich in whole foods like salmon for omega-3 fat, DHA, leafy greens for vitamins and minerals, and eggs for choline.
Week 22: Baby is the size of a package of Organic Valley butter.
Your baby is measuring around 11 ½ inches long and weighs around 1 pound. At this stage, you might want to consider working with a pregnancy dietitian if you haven’t. Research confirms the positive impact and influence of a nutrient-dense diet during pregnancy not only for the mother, but also the baby, for better birth outcomes, postpartum health, transgenerational health, and more.
Week 23: Baby is the size of a grapefruit.
In the second half of your pregnancy, your protein requirements increase to about 100 grams per day, so remember to eat a well-balanced breakfast every day and make sure to add high-quality protein whenever possible such as full-fat dairy and eggs.
Week 24: Baby is the size of a corn cob.
Your baby has accomplished a lot already! By this week, they are about 14 inches long and they’ve developed all of their facial features—who do you think they’ll look like?
Week 25: Baby is the size of an acorn squash.
Your baby is starting to develop more body fat now and weighs around 1.75 pounds. Drink plenty of fluids and take your prenatal vitamins daily. When mixed with Organic Valley milk, each serving includes 17 grams of high-quality protein and essential nutrients, like calcium, DHA, vitamin B12, and more.
Week 26: Baby is the size of a quart of milk.
Continue to drink quality full-fat cow’s milk for healthy fetal growth and development. Cow’s milk contains vitamin B12 which you need 2.6 micrograms daily while pregnant and new research suggests maybe even more. One 8-ounce glass of milk delivers around 1.3 micrograms of vitamin B12 so bottoms up!
Week 27: Baby is the size of a newborn goat.
Around 27 weeks, your baby weighs about 2 pounds and they will open their eyes for the first time! Organic Valley pastured eggs are a fantastic source of pre-formed vitamin A (retinol) to help support baby’s development and keep them thriving!
Week 28: Baby is the size of a bag of brown sugar.
Welcome to the first week of the third trimester! Your baby can blink their eyes now so get ready for them to start batting their lashes at you and melt your heart.
Week 29: Baby is the size of a duck.
At week 29 your baby weighs about 3 pounds. Is your growing baby keeping you awake at night? Try reducing stimulants like caffeine and screen-time especially before bed, minimize eating right before bed to reduce indigestion, and balance your blood sugar at meal and snack times. Using essential oils, drinking calming tea, and practicing mindfulness are other sleep strategies you can try.
Week 30: Baby is the size of a cabbage.
Eat your vegetables! Vegetables like cabbage have high amounts of vitamin K that help manage normal blood clotting and can lower your risk for postpartum bleeding. Greens also contain potassium which is an important electrolyte for managing your blood pressure and may prevent swelling.
Week 31: Baby is the size of a baguette.
At this stage of your pregnancy, you’re gaining around 1 pound per week with half of that going directly to your baby. It’s common for women to have mixed feelings about a rapidly changing body. Remember, you’re doing one of the most important jobs there is—growing a tiny human!
Week 32: Baby is the size of a coconut.
You may want to consider finding a certified postpartum doula. They will provide in-home care for the birthing person, your baby, and family members by offering breastfeeding information, sleep support, cooking, light cleaning, and so much more.
Week 33: Baby is the size of a half-gallon of Lowfat Chocolate Milk.
Organic Valley Lowfat Chocolate Milk has 8 grams of high-quality protein, plus vitamins A and D, calcium, iron, potassium, and more.
Week 34: Baby is the size of a honeydew melon.
By now, your baby is likely in an optimal birthing position with their head facing down. Their lungs are fully formed and they will spend the next few weeks maturing.
Week 35: Baby is the size of a butternut squash.
It’s time to pack your overnight bag for the hospital or birth center. Even if you’re planning on a homebirth, consider putting together a collection of items you’ll need for baby feedings, diapering, and postpartum self-care.
Week 36: Baby is the size of a chicken.
Your baby is growing fast, gaining around 1 ounce on average per day. At week 36 your baby is about a whopping 6 pounds!
Week 37: Baby is the size of a head of kale.
Your baby is almost full term—the countdown is on! They weigh on average 6.5 to 7 pounds now and just like kale, they are about 19 inches tall.
Week 38: Baby is the size of a leek.
Remember to stay active and keep moving your body as you’re able to. Going on a 20- to 30-minute walk daily is the perfect amount to help you manage swelling, blood sugar control, and can even help you sleep better at night.
Week 39: Baby is the size of a watermelon.
Weeks 39 to 40 are considered full term. Yahoo, you’re so close to meeting your little one!
Week 40: Baby is the size of a gallon of milk.
You made it to 40 weeks—congrats! Your sweet little baby will be here any day. We wish you the best and safest birth experience and look forward to continuing to nourish you and your family as it grows.
Carly Knowles , MS, RDN, LD, PCD is a master's-educated registered dietitian nutritionist, postpartum certified doula, and cookbook author of “The Nutritionist’s Kitchen.” She specializes in perinatal care including individual and group nutrition counseling, as well as media consulting for healthy food brands. For other helpful, straightforward, evidence-based pregnancy information, recipes, and recommendations, visit carlyknowles.com and check out her cookbook “The Nutritionist’s Kitchen: Transform your diet and discover the healing power of whole foods.”