Think about prenatal testing

During the second trimester, your healthcare team may offer you prenatal tests. These might include:

• Genetic tests. Blood tests can screen for conditions caused by genes or chromosomes. These include tests for spina bifida and Down syndrome. If your results cause concern, your healthcare team likely will suggest a diagnostic test, most often chorionic villus sampling or amniocentesis.

  During chorionic villus sampling, a sample of the placenta is taken for testing of the baby's chromosomes or genes. During amniocentesis, a sample of the fluid surrounding the baby is removed from the uterus for testing.

• Fetal ultrasound. Fetal ultrasound is an imaging test that uses sound waves to make images of a baby in the uterus. An ultrasound can give useful information about the baby. Fetal ultrasound also might tell you the baby's sex if you want to know.

• Blood tests. Blood tests between weeks 24 and 28 of pregnancy can check your blood count and iron levels. And they can screen for diabetes that can start during pregnancy, called gestational diabetes.

  Blood tests also check for your Rh status and Rh antibodies. Rh factor is a trait passed through families, also called an inherited trait. Rh factor is a protein found on red blood cells. If your blood is Rh negative, you need a blood test to check for Rh antibodies.

  You might have these antibodies if your baby has Rh positive blood and your Rh negative blood mixes with your baby's blood. Without treatment, the antibodies could attack the baby's red blood cells.