Chinese Gender Calender Prediction

Megan
How accurate is this gender prediction Calender for all of you? It's 100% for all my siblings and niece and nephew and all my friends children! I was 25 at time of conception in March, if this is right we are having a girl, but we are still waiting till birth to find out :) December 12th can't come soon enough!! Xoxo 
http://www.thebump.com/chinese-gender-chart