Week 16

You:

An ultrasound will likely be performed around week 16. This enables the doctor to determine fetal age, and observe organ development, as well as detect certain defects if they are present, mainly of the head and spine.  It can also determine whether you have multiples and even the gender of your baby, although for gender it's not 100% this early on. For women over the age of 35,  amniocentesis may also be recommended around this time. This tests mainly for Down's syndrome as well as some other genetic problems. However, there is a very small amount of risk involved in the procedure, so you'll want to weigh the pros and cons with your doctor. Around this time you may also begin to feel the baby move, especially if you have had children before or if you are thin. 

Your baby:

Fat starts to form just below the skin. The genitals are now developed enough that a sonographer may be able to determine your baby's gender. Baby's heart is pumping at twice the rate of yours. Baby is now sucking, swallowing and blinking, and possibly even hiccuping! Baby has also learned to breath, inhaling and exhaling amniotic fluid, which helps the lungs develop. Baby is now almost 5 inches long and weighs about 100 grams.