Hi Udoka, and congrats on the pregnancy!
I'm afraid that unless there are specific medical circumstances for your pregnancy that make sex unwise, there's really no medical reason why you can't have sex throughout pregnancy. Most women don't even know that they are pregnant in the first couple of months, so it would be quite unfortunate if sex weren't safe then.
However, it is perfectly normal for you to be off sex as your hormones go a bit crazy and you're physically exhausted, and part of your husband being supportive should be to understand and accept this as part and parcel of pregnancy.
It's often the case that a woman's sex drive comes back after the first trimester, and sometimes pregnancy sex can be amazing, but until you feel like sex again it's not much to ask your husband to be patient and supportive.
Try printing out the articles on the site that show what your body is doing in these first three months, so that he can understand that you have quite a lot to cope with right now, you're busy making his baby!