There are classical reference about getting the desirable sex of the child in ayurveda, it is very well described in allthe major ayurvedic texts in the Shareera shtanam (ayurvedic anatomy)
in Ashtanga Hridayam AD800 it was been described in the chaptor Garbha vakrantheyam(embryology)
and accordingto the text this treatment should be done in the endo of the first month , but there was no supporting evidence or studies done ,
but it sounds very logical that , the sex charectors are developing in the end of the first month according to embryology, so i think ayurvedic treatments were indirectedly intended to fix the sexual charectors rather than getting the desirable sex for the child.
and the treatmens are targeting the head through the nostrills , i hope it could influance the endocraine centre ,