sciatic pain?

I am hoping someone can help me. I am 23 weeks pregnant and have been having sciatic pain. It is usually at my lower back and butt area. Now for the question, does anyone get numbess from sciatic nerve irritation. The lower part of my left thigh and my left knee has been numb for a week now. I thought I had irrtated a nerve in my leg with an injection (I take daily blood thinner injections in my thighs) but the nurse said if that was the case it would be better by now. So she suggested it is from the sciatic nerve. So does anyone else have experience with numbness in their legs? TIA