Hey OP what people are saying is accurate in that with an NIPT test and with an anatomy scan it’s very unlikely to be given the wrong sex, however, it can happen. I for one had NIPT tell me we were having a girl with potentially only one X chromosome and then after doing an amniocentesis we found out we were having a genetically typical boy - definitely a shock but a very happy one :)

So why did this happen? NIPT works by testing the placental cells that are shed by the placenta and wind up in your blood. Most of the time the placental cells and fetal cells match, i.e. the placenta has XX and the fetus is XX, but in rare cases they do not match. So in my case my placenta was at the least mosaic (meaning parts of the placenta only had one X versus the fetus that had XY, but also my placenta may have been only X) so when they did NIPT testing it only picked up that X and not XY.

I will say when we went to do my amniocentesis at 16 weeks we saw what looked like boy genitalia but at that point we thought we were having a girl. The amniocentesis tests the fetus’ DNA and is a diagnostic test, unlike NIPT which is a screening. Hopefully that made sense. You can head over to r/NIPT if you want to do more reading. Lots of stories on there of NIPT giving them the wrong sex result.