That is the thrill of bowhunting my friend. A couple tips for you. The first is start lifting weights or even use your bow to build your shoulder muscles. I stopped working out for a few years and started back this year and i feel like i can hold my bow back forever if i had to. The second tip is that even if your wife goes into labor while you are hunting, there is plenty of time for you to get there before the baby comes. You can ask your doctor or anyone else that has had a baby. Good luck