I doubt they care much where someone inserts their phallus in their free time, they have far more pressing matters. Looking to history for example doesn't really help either, SoB are nuns, for example, but take no vow of chastity.
I vaguely recall something about the children of Guardsmen and Guardswomen being sent to special institutions, perhaps the Schola Progenium or something. I would be very surprised if they discouraged sex, and with commissars about one assumes it isn't too detrimental to morale.