The egg only has 50% of her DNA, so it's not her body.
Let's make it more simple:
The human body has 46 chromosomes. 23 from the man and 23 from the woman. If the pre-embryo is female, one pair is XX. Male is XY.
So, if the pre-embryo is a female, then it's a 50-50 split. If male, then about 49.5% of the pre-embryo is his and 50.5% is the woman's - based on the presumption that there is less genetic material in a Y chromosome compared to an X. Therefore, she has a majority stake at best (XY) and an even split at worst (XX).
Then again, there's mitochondrial DNA which is solely provided by the female, that would probably put ownership in the woman's court in all cases except for the following situation:
Things get muddied when you have some pre-embryos with multiple X or Y chromosomes. One would have to find out which parent they came from first. XYY syndrome - father has majority rights. XXX syndrome, one would have to determine which parent's reproductive process malfunctioned before assigning parental rights.