Will it work? Yes! This semi-invasive procedure is a slam-dunk way to know your baby's gender for sure, but because of the small risk of miscarriage your doc probably won't green light it for curiosity alone. "An amniocentesis involves putting a needle into the fluid surrounding a baby, and then looking at the chromosomal makeup of that baby, which reveals gender as well as any chromosomal abnormalities," explains Dr. Michael Randell, an OBGYN in Atlanta. "Unless someone mislabels your results, this test is entirely accurate."