Importance of full ultrasound during pregnancy? - Page 2
Not to downplay the seriousness of the condition, the most typical symptom of placenta previa is third trimester bleeding, at the point when small cervical changes are beginning to happen. Most women don't go that far into pregnancy without discovering it by ultrasound.
The placenta also sounds different than the baby's heart rate, or mom's heart rate, and it's often possible to get a general idea of the placenta's location. I'd imagine that if it's heard down low as the pregnancy progresses, that in itself might be an indication to take a peak with ultrasound.
It was during my anatomy scan, at 19 weeks. I had another one done just prior to the time they would have wanted to have done a scheduled c/s, because I was advocating for a trial of labor and they were considering it based on how far the placenta was from the os (I had complete, but it did end up moving to 0 cm from the os; no-go for a trial)
bbycap, I am not a trained physician, but my understanding is that typically the "3 lines" means it's a girl, although they can also show up in boys. 16 weeks, IIRC, is on the early side of being able to tell for sure, it might be better to wait for a later ultrasound. Congratulations on your baby, whatever gender it is! :)