- Preimplantation Genetic Diagnosis (Prior to Embryo Return during IVF)
- Prenatal Genetic Testing (Amniocentesis or Chorionic Villus Sampling (CVS) (First Trimester))
- Ultrasound (Best 18-22 weeks gestation)
Each of these has their own risks and benefits. Some are even more accurate than others. They also vary as to at what point in or before pregnancy they can be done.
What you have to remember about all of these methods is that they vary widely on when they can be done, when they are most accurate and if they are accurate enough for the purposes you need. Always be sure to talk to your doctor or midwife about finding out, before you try to find out. is can help prepare you for the realistic view of the chances the answer you're looking for is really accurate. A good example might be a really early ultrasound and someone slips out with a pronoun - that's not as likley to be accurate at that point.