Yes and no. There is a lot of talk (and many books written) about how to choose the sex of your baby. Many of these talk about the timing of intercourse in relation to ovulation, positions used at the time of intercourse, and even the month and year that you conceive.
It is very controversial as to the efficacy of these methods and in someone who is strongly desirous of gender balance in their family (and other women may require a specific gender because of genetic problems) they should speak to their gyn who may recommend consultation with a reproductive endocrinologist.
Repro endo physicians have tools at their disposal that have proven to dramatically alter the ratio of one sex over the other. Methods range from sperm sorting (separating the X and Y sperms in the laboratory and then inseminating the woman with a specific group of sperm) to PGD (preimplantation genetic diagnosis) where the sex of the embryo is determined prior to placing it into the uterus for implantation.