Determining the sex of a child is all down to chromosomes.
"The nuclei of human cells contain 22 autosomes and 2 sex chromosomes. In females, the sex chromosomes are the 2 X chromosomes. Males have one X chromosome and one Y chromosome. The presence of the Y chromosome is decisive for unleashing the developmental program that leads to a baby boy. "
I'm sure most parents will be happy with whatever sex their child is. I don't like people messing around with trying to determine their child's sex before conception.