To Tell The Hubby or To Not Tell The Hubby...That Is The Question.

So my hubby and I have a precious 13 month old boy named Josiah. My hubby has two more boys from a previous marriage. We wanted a girl real bad so we looked up ways on how to increase your chances on how to have one. I believe I'm pregnant but my hubby doesn't know yet. My question is should I keep the pregnancy a secret and wait the 13 to 20 weeks to find out the sex of the baby then surprise him if it's a girl or will it be too much work?