I thought it was a long tradition that Hijra would adopt unwanted children. I've certainly heard of it, often abandoned baby girls, they also take in older children who are seen as transgender or homosexual.
It is a tragedy that babies are abandoned and left to die. Maybe life with a Hijra mother is preferable.
I believe the "being in tact" is likely to be because castration used to be done by non medical people with no pain relief and all too often ended in death from bleeding or infection. I would imagine that even now a professional surgical sex reassignment would be something many could not afford so the choice would be a brutal castration or remaining intact.