When you see your healthcare provider and talk about what tests should be done in the second trimester, you may find out about a couple of different tests and these prenatal tests are emerging and changing all the time. One test is an ultrasound that's done about 18 to 20 weeks, and it's an anatomical ultrasound, which has a really good look at the baby's growth and organs to determine if the baby is growing and developing appropriately. Another test that's done often is the maternal marker screen or the triple screen. And it looks at HCG estriol. And alpha-fetoprotein essentially, it's trying to get an indicator as to whether your baby has down syndrome, trisomy 18 or spinal bifida, which is a neural tube defect or an opening in the spinal cord. Now, if those tests come back positive, it does not mean that something is wrong with the baby. They're simply an indicator that you need to move on to a more aggressive or invasive tests like an amniocentesis, which takes a little bit of amniotic fluid or chorionic villus sampling, which takes a little piece of the placenta, thereby actually testing the baby's genes to rule out these problems. So those are the kinds of tests that your doctor is going to talk with you about in the second trimester to make sure that your baby is growing and developing appropriately, and that you both stay healthy.