Starting 16

-Week Sixteen
Fat begins to form underneath skin, providing your baby with insulation for the coming months.
Did you know that both baby and placenta are now about the same size?
Your little one has reached 4.57 inches (11.6cm) and approximately 3.53 ounces (100gm).
His head and neck are held straighter now.
This is a week of "mights!" You might hear the tiny thumps of his heartbeat with an external monitor now. The genitals are developed sufficiently that an experienced sonographer might be able to determine if your baby is a boy or a girl.
Her heart is pumping as much as 6 gallons of blood a day and beats at a rate about double your heartrate.
If you could take a peek inside, you would witness your child's reflexes in action! (Sucking, swallowing and blinking are now evident.) She is probably even hiccuping even though you don't feel it yet!
Your baby has learned to breathe! This is apparent from the regular movements of his chest. Isn't it amazing that he is able to breathe "underwater," inhaling and exhaling small amounts of amniotic fluid? These actions help the lungs to develop and grow.