When I'm not pregnant a minimum of three times a week is healthy for us. DH is good with that. On average though it's more like five times a week. When I'm pregnant, healthy varies. With my first two pregnancies my sex drive went through the rough so our sex life got a lot busier. With my third pregnancy DH worked between 80-100 hours a week so our sex life was minimal...maybe once a week. This time my sex drive is down, so DH is lucky to get sex once a week.
We're in our mid-twenties and sadly have sex every few weeks. I'm pregnant for one and for two he wants me to make the move and I'd rather sleep and when he makes the move its in a total creepy grope me way.
4-7 times a week.... but in all honesty, it's more for us but I know some people are not as sexually driven so I think it depends on both people in the relationship and making sure you are sexually compatible.