I have a girl child and am planning for the second child. I definitely would like to have a boy?

Chromosome Screening. There is finally a good technique for selecting sex in a child, comprehensive chromosome screening (ccs). Ccs is a form of in vitro fertilization where chromosomes in the embryo are counted. Embryos with normal chromosomes can be transferred, with high pregnancy rates. Ccs is the only currently available technique that works for sex selection, also reducing aneuploidy and miscarriage risk.
Sex of a child. The sex ratio of males to females born is 51% to 49%. So if you do nothing there is a slight increase in the chance of having a boy. The only technique reported in the medical literature, in many publications over 30 years, to influence the outcome is the ericsson method of sperm separation. This will increase the odds of having a boy to 70%; "www.Genderselection.Com".
IVF with PGD is best. With in vitro fertilization (ivf) we can test which embryos are boys vs. Girls. 2 choices: just test gender (x & y chromosomes) or check all 24 chromosomes ('comprehensive chromosome screening' or ccs). Can test embryos on day 3 or day 5 / 6. Ccs looks promising but is not a panacea - it should reduce miscarriage risk but all the evidence is not in. If you want family balancing see a fertility md.