
"Your baby measures about 1 3/4 inches to 2 1/4 inches (44 to 60 mm) from crown to rump, and weighs about 1/3 oz (8 g).
Your baby's development has passed its critical stage, and from now on she'll be at less risk of developing any sort of congenital abnormality or being affected by most infections and certain drugs.
By the end of the week her body will double in length, and her head will be almost half the length of her body. Underneath her fused eyelids, the irises start to develop and these will later protect her eyes from too much light. However, her ears won't be fully developed for some time. Even this early on, your baby can yawn, suck, and swallow.
Your baby's vital organs--liver, kidneys, intestines, brain, and lungs--are fully formed and beginning to operate. For the rest of the pregnancy they just need to grow. Finishing touches, such as fingernails and downy hair, start to appear. Her heart carries on pumping blood to all her internal organs, including the umbilical cord, which transfers blood to the placenta."
- from "The Pregnancy Bible" by J. Stone and K. Eddleman