According to reports, a source claimed that Kim and Kanye made sure their new baby was a boy by choosing only male embryos.
From Us Magazine:
Reality star Kim Kardashian, 34, and husband Kanye West underwent an IVF gender-selection process this spring to predetermine baby No. 2’s sex. “She only had boy embryos implanted,” says a source close to Kardashian, who confirmed the gender on Monday June 21, after Us Weekly broke the news. During the procedure — which can start at roughly $17,000 — doctors isolate fertilized embryos of the preferred sex in a lab, then transfer them to a uterus.
“Kanye and Kim are so excited to complete their family,” says another source of the parents of daughter North, 2. “Kanye loves Nori more than anything, but to make his world complete, he wanted a little boy, an heir,” says a source close to West.