Is my garden snake going to have babies?

ok so i have 5 garden snakes and i keep them in a 20 gallon tank. i caught them in my backyard 4 months ago. i have a heat lamp,big water bowl,a house,a log and the bedding that u put down for them. i feed them night crawlers. well when i went to go feed one of my garden snakes its stomach was huge like really big. btw it has been like that for a couple of weeks where it looks like it ate something big. lol i know it didnt eat any of my other garden snakes. and so i was wondering what other ppl think. does it sound like it is going to have babies.thaxz