Husband wants to have sex and I don’t

Ever since I had my first baby I’ve had no desire to have sex unless I’m in the mood which is rare. Like maybe once a month. He gets so upset when I don’t want to but I stand my ground. I’m currently pregnant with our second and I have ZERO want for sex, especially since I feel sick 24/7.

What do I do? How can I get my sex drive back? I want to have sex with my husband but if I’m not in the mood it makes everything so much harder. Please help.