Ay sis, this happens more often than people think! A few of us in our barkada had wrong gender reveals, one friend thought she was having a girl but boy pala sa delivery, so frustrating kasi the whole nursery and clothes na inayos na niya haha. I think it really depends sa positioning ng baby during the ultrasound at kung malinaw makita ng technician, especially kung maliit pa or covered pa ng cord, kaya ang best talaga is mag-confirm ulit sa next ultrasound or closer to delivery para sigurado na.