This is a big week for you and your baby — you've officially entered the second trimester. The placenta has developed to provide your baby with oxygen, nutrients and waste disposal. It also secretes the hormones progesterone and estrogen, which help keep your pregnancy steady.

Your baby continues to develop significantly. One thing that is apparent is the slowdown in the growth of your baby’s head in comparison to the rest of the body. Your baby’s face is also starting to look more human as its eyes are beginning to move closer together and the ears are moving to their normal positions.

Internally, your baby’s intestines are developing villi which aid in digestion and the intestinte are migrating from the umbilical cord into their abdomen. The liver also begins to secrete bile and the pancreas begins to secrete insulin. Your baby is also starting to practice swallowing as it takes in amniotic fluid and passes it out as urine.

At this point, your baby may also be able to put a thumb in his or her mouth, although the sucking muscles are not fully developed yet. All twenty teeth have formed and are laying under the gums. Your baby can also smile and its vocal cords are rapidly developing. The external genitalia have also developed enough that you would be able to distinguish between male and female if you looked at the baby though an ultrasound.

Your baby weighs between 13 and 20 grams (.5 and .75 ounces) and is approximately 2.5 to 3 inches long. The placenta and your baby also weigh the same now. Your baby’s vital systems are all fully developed and will now concentrate on growing (at rates up to 1 inch / week!).