This is a risk that comes with long or short cycles. In most cases low spermcount can/is correctable, but not always. The risk is not that great, but is something you should weigh out before hand...
You could always have the kids, then do gear. I had Kids, Got a vasectomy, and now have to do gear b/c of the vasectomy. Not to bad getting my test from the doc and never having to come off. I wouldn't recomend the vasectomy though.