About My swordtail's fry, what to do?

here's the scenario, I have 1 male swordtail, 3 females, I think one of the female is pregnant, and I can't separate her in another tank for I don't have another tank, and I can't buy another yet, what if my female swordtail gave birth on the tank with the other two female and the male, will my fry likely to survive, also in my tank there are no other fishies, just swordtails, and no aquatic plants just big marbles, and some sand and the filter,,