Fetal Development Timeline

week 5

Jan 22, 2013

Your baby now resembles a teeny tadpole (complete with a tiny tail) and is about the size of an orange seed. The circulatory (or blood) system, along with the heart, is the first part of that tiny body to be functional; and as your baby's heart starts to form, you may even be able to see it beating on an early ultrasound. A

week 7

Feb 5, 2013

he big news this week: Hands and feet are emerging from developing arms and legs — although they look more like paddles at this point than the tiny, pudgy extremities you're daydreaming about holding and tickling. Technically, your baby is still considered an embryo and has something of a small tail, which is an extension of her tailbone.

week 10

Feb 26, 2013

hThough he's barely the size of a kumquat — a little over an inch or so long, crown to bottom — and weighs less than a quarter of an ounce, your baby has now completed the most critical portion of his development.

week 15

Apr 2, 2013

Although her eyelids are still fused shut, she can sense light. If you shine a flashlight at your tummy, for instance, she's likely to move away from the beam. There's not much for your baby to taste at this point, but she is forming taste buds.

week 17

Apr 16, 2013

[My how your baby has grown! She's about the size of your palm, weighs about five ounces, and is developing some body fat (join the club, baby!). Her heart is now regulated by her brain](http:// http://www.whattoexpect.com/pregnancy/week-by-week/week-17.aspx)

week 22

May 21, 2013

This week, your baby weighs in at a whopping pound and measures nearly eight inches, about the size of a small doll. But your little doll (who now has eyebrows, eyelashes, and maybe even some hair on that little head) is a living one who can now perceive light and dark. She can also hear your voice, your heartbeat, your gurgling stomach, and the whoosh-whoosh of blood circulating through your body.

week 25

Jun 11, 2013

Your baby is growing by leaps and bounds, reaching nine inches in length and passing the pound and a half mark. Under his skin, capillaries are forming and filling with blood and by week's end, air sacs (also lined with capillaries) will develop in his lungs, getting them ready for that first breath.

week 30

Jul 16, 2013

Your belly’s increasing size is a definite clue that your baby is getting bigger every day, weighing in at over three pounds now (he’ll be packing on the weight at a rate of half a pound per week for the next seven weeks). Also growing daily is his brain, which is actually starting to look like the real thing with those characteristic grooves and wrinkles.

week 34

Aug 13, 2013

<a href='http://www.whattoexpect.com/pregnancy/week-by-week/week-34.aspx' >What's new this week? Your baby is clocking in at five pounds and could be as tall as 20 inches by now, and the vernix (the white coating protecting your baby’s skin) is getting thicker. This week, a boy's testicles start making their way down from his abdomen to their final destination: his scrotum (look out below!). While about three to four percent of boys are born with undescended testicles, it's nothing to worry about — they usually head downtown before junior turns a year old.

week 38

Sep 10, 2013

Hey, your little one isn't so little anymore, weighing close to seven pounds and measuring 20 inches long. Fetal development is nearly complete as your baby tends to a few last-minute details like shedding the skin-protecting vernix and lanugo. He's also producing more surfactant, a substance that prevents the air sacs in his lungs from sticking to one another once he starts to breathe.