I think that in an orthodox society like India sex determination of an unborn child should not be permitted because it will definitely be misused by the would-be-parents to eliminate the female child. In India it is still a great phobia that a female child is a great burden on the parents. It is contrary to democratic spirit and to equality to sexes.
The indiscriminate killing of female foetus may result in a very critical situation. When the number of females in a society is extremely low there will be fights among men for possessing females.
In India majority of the people wrongly believe that birth of a male or female child totally depends on Chromosomes belonging to the female and so they start condemning females who give birth a female child. If they come to know about female foetus earlier, there is a possibility that cracks in their married life may develop. So in order to preserve harmony in the family and moral values in society, sex determination of an unborn child should not be permitted.