No. The sex assignment of your baby depends on the father. A woman's egg has an x chromosome. The father's sperm carries either an X or a Y chromosome. If the one with the x chromosome is the one that reaches the egg, you'll have an XX chromosome baby (a girl) if the Y chromosome reaches the egg, you'll have an XY chromosome baby (a boy) The only way to determine is if a lab took a sample of the father's sperm and figured out which sperm has an x or a y chromosome. Then filtered out the one's with the chromosomes you don't want. However, I suggest just letting nature take its course. You'll love the baby no matter what gender it is.
It all depends on what sperm fertilizes the eggs because sperm carries either the X or the Y chromosome. If the Y fertilizes the egg it will be a boy and if the X fertilizes the egg it will be a girl. (Hope I don't gross you out but it's the truth) So the easy answer is no you can't determine the gender before pregnancy. I hope this helps you....it just so happens to be what I'm learning in science at the moment.
In fact yea, Male sperm is clearing all, Sperm once coming for girl once coming for boy with test on Sperm in official Clinics, you can see which is gonna be But in some ways going to be harder cause it depends on girl's body too, in sex Millions Sperm going to Merge with Girl's chromosomes & between those millions sperms only one will take another Girls"s chromosome & it will start Process , so by some tests on Male's sperm, & Girl's chromosomes & body's positions you can do that :)