At 13 weeks pregnant, you're in the final week of your first trimester. (Can you believe you're already a third of the way through your pregnancy?!)
If you're like many parents-to-be, you may begin to tell people you're pregnant around week 13, but it's up to you when to give friends and family the news that baby is on the way.
Your Baby at Week 13
Your sweet fetus has grown to three inches long — about the size of a sweet Georgia peach — and now her little body is poised to begin growing at lightning speed. What’s the rush? Well, it’s got to catch up to that noggin, which makes up half of your baby’s body size at this point. And catch up it will. By the time your little star makes her grand entrance, that head will be only one-fourth the size of her body.
More big progress this week: The intestines complete their move out of their storage space in the umbilical cord and into their permanent home in baby’s belly. To nourish that tiny tummy and the other systems and organs that are growing like crazy, baby’s lifeline — the placenta — is expanding. It weighs just an ounce now, but at birth it’ll tip the scale at a full two pounds! That’ll sure help to explain your blossoming belly in the weeks to come.
There are plenty of subtle changes happening this week as well: fingernails and downy hair on the body continue to make their appearance. Baby’s bones continue to harden. And those genitals begin to take on their gender characteristics, but it’s still too early to tell by looking whether you’ve got a bouncing baby boy or girl inside.
The muscles of the chest wall are starting to develop, and though she’s nowhere near ready to breathe, she’s already practicing up with little breathing movements. And long before baby says her first “mama” or “dada,” her vocal cords are forming, gearing up for that very anticipated first cry…the first of many, that is!
At a Glance
13 weeks pregnant is how many months?
If you're 13 weeks pregnant, you're in month 3 of your pregnancy. Only 6 months left to go! Still have questions? Here's some more information on how weeks, months and trimesters are broken down in pregnancy.
How big is my baby at 13 weeks?
Besides being as large as a lemon now, that head of his is now about half the size of his crown-to-rump length. That's one reason why your little one looks more like an alien from outer space at this point. By the time you give birth, his body will catch up, measuring three-quarters of his total size.
But don't compare your fetus with the fetus next door. Starting in the next week or so, babies begin growing at different paces, some faster than others, some more slowly, though they all follow the same developmental path.
Baby's intestines and vocal cords are developing
What else is going on in there? At 13 weeks pregnant, tiny bones are beginning to form in his arms and legs. Because he can move them in a jerky fashion, he may be able to get his thumb into his mouth soon — a habit that may come in handy for self-soothing when he's a newborn.
Your baby's intestines are also in for some big changes. Until recently, they've been growing in a cavity inside the umbilical cord, but they've just moved into their permanent — and more conveniently located — address, in your baby's abdomen. And to serve your growing fetus' needs, the placenta is also growing, eventually weighing 1 to 2 pounds at birth.
Also developing this week: your baby's vocal cords (the first step toward saying, "I love you, Mommy!"). You obviously can't hear him crying or cooing just yet, but you can bet that little voice will get a good workout once he's born.
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