13 Weeks Pregnant: How Big is My Baby?

It's hard to imagine the growing inside your womb, especially at just 13 weeks into your pregnancy. At 13 weeks, your baby is big enough that he's starting to look human, but small enough that you haven't yet felt him move. If you need help visualizing just how big your baby is at this stage, read on for more information about the size of a 13-week-old fetus.

The Baby's Exact Size

Thirteen weeks after your last menstrual period, your baby is eleven weeks post-conception. During the thirteenth week, he will grow a full half-inch. At the beginning of week 13, your baby is about 2.91 inches long. By the end of the week, he will have reached an impressive length of 3.42 inches from crown to rump. He will also gain quite a bit of weight (relatively speaking). At the beginning of weak 13, your baby weighs about a half-ounce. By the end of the week, he weighs .8 ounces.

A 13-Week-Old Fetus is the Size of...

Numbers don't always work when you try to envision what your baby looks like, but comparison may help. At thirteen weeks, a fetus is about the same size as a jumbo shrimp. From crown to rump, he's about as long as the width of a drinking glass or a soda can. By the end of the week, he's about the size of a computer mouse.

What the Baby Looks Like

Your baby's head makes up about a third of her total body size at 13 weeks gestation. Her skin is very thin, so you would be able to see her organs, veins and arteries through it. Altough you wouldn't be able to tell from an ultrasound, a baby at this gestational age is beginning to show external gender characteristics. She is also beginning to develop reflexes and may jump when startled. Your little one will be a "real" baby before you know it!