The Baby's Exact Size
At the beginning of the twelfth week of pregnancy, your baby is ten weeks from his date of conception. He is about 2.1 inches long at the beginning of the week, and will grow almost an entire inch by the end of the week. He weighs one half-ounce and, if you are sensitive, you may be feeling tiny fluttering kicks inside your womb.
An Twelve-Week-Old Baby is the Size of...
Numbers can't always enable you to understand the size of a fetus or embryo, but comparison can help to offer more accurate visualization. At twelve weeks, your baby is about the same size as a lime or a lemon. He is about as long as your thumb or your ear. Although still small, he looks more and more like a human being as each day passes.
What the Baby Looks Like
Your unborn baby now looks, more or less, like a baby. His inner organs are essentially formed, and his brain is growing rapidly. If you could look inside your womb, you would be able to discern ears, eyes, a nose and a mouth. The baby has tiny fingers and toes which are no longer webbed together, and she now has reflexes. She startles in response to loud sounds and may have the simple reflexes involved in sucking, blinking and grasping. As you enter your second trimester, your baby begins a period of fast growth to prepare for outside-the-womb survival.