A 25-year-old client at 7 weeks’ gestation comes to the clinic for her first prenatal visit. The client tells the midwife that a friend recently gave birth to a baby with Down syndrome and that she is concerned about her baby’s chances of developing the same diagnosis. The midwife informs the client that a combined first trimester screening test may be ordered as early as the 11th week of her pregnancy to help evaluate the fetus’s risk for chromosomal abnormalities. The midwife informs the client that all of the following tests are included in the combined first trimester screening test except:
