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How Big is My Baby? An Easy Week to Week Growth Guide

Learn how your baby is growing during each week of pregnancy

With each week that passes during your pregnancy, it can be hard to see growth in your belly – especially early on. But that doesn’t mean your little one isn’t growing away in there. We’ve broken down your baby’s growth by week in this simple guide to help you visualize how your little one is developing.

First Trimester Pregnancy Ultrasound

Baby Growth During Weeks 6 Through 12

Your baby at 6 weeks: At six weeks along, your baby is around the size of a lentil. He is about .25 inches long and within the next week, will double in size. A nose, eyes, ears, cheeks and chin are beginning to develop at this point.

Your baby at 8 weeks: Within two weeks, your baby has grown to the size of a kidney bean. He’s just bigger than ½ inch in length and is beginning to move around. He’s also starting to form taste buds.

Your baby at 10 weeks: At week 10, your baby is about as big as a strawberry. Hair and nails are starting to form and all of his vital organs have developed. He’s likely over an inch long.

Your baby at 12 weeks: Once you’ve reached the 12-week marker, your baby is the size of a lime. His brain is quickly developing, as well as his reflexes. The average fetus is about 2 inches long by this time.

Second Trimester Pregnancy Ultrasound

Baby Growth During Weeks 15 Through 25

Your baby at 15 weeks: Within three weeks, your little one has grown a lot – he’s now the size of an apple. Measuring around 4 inches, he’s likely moving around a lot more by now.

Your baby at 18 weeks: At 18 weeks pregnant, your baby has grown to the size of a bell pepper. You may be able to feel more movement now that he’s over 5 inches long and has the ability to yawn, hiccup and swallow.

Your baby at 20 weeks: Now that you’re 20 weeks pregnant, your baby is about 6.5 inches long and is close to the size of a banana. His taste buds are completely functional and he’s consuming more fluid now than ever before.

Your baby at 25 weeks: Five weeks later, your little one is as big as a head of cauliflower. He’s getting fatter, growing more hair and can sense the difference between up and down. At this point, he probably weighs between 1 and 2 pounds.

Third Trimester Pregnancy Ultrasound

Baby Growth During Weeks 30 Through 40

Your baby at 30 weeks: Beginning at week 30, you’re in the home stretch. Your baby is about the size of a large head of cabbage and he’s getting stronger by the day. He likely weighs between 2.5 and 4 pounds and measures between 15 and 17 inches long.

Your baby at 32 weeks: At week 32, your baby is likely positioned with his head down and is the size of a squash. He’s still growing daily and if necessary, is developed enough for birth.

Your baby at 36 weeks: Once you hit 36 weeks, your baby isn’t so tiny any longer. He’s around the size of a head of romaine lettuce and is his liver, kidneys, and circulation and immune systems are fully functioning. He’s close to being able to breathe on his own and could arrive any day.

Your baby at 40 weeks: If you’ve made it to 40 weeks, your baby is the size of a small pumpkin. The average fetus is 19-20 inches and weighs between 6 and 9 pounds. His hair and nails are continuing to grow, but he’s ready to be introduced to the world.

Want to learn more pregnancy tips? Get all of our best advice here!


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