Nexium while pregnant

Hi ladies! So I'm having a hard time with heart burn. I've always had bad heart burn, but then when I was pregnant with my daughter it got worse. I did take nexium with my first but it was more towards the third trimester.  Now I'm pregnant with my second and heartburn has been bad but I'm only 12 weeks and 3 days. The doctor I have this time said we can talk about me taking nexium but he doesn't really want me to. I've read that it shouldn't cause any harm, especially after 13 weeks. I'm desperate for relief. Anyone else taking it? Sorry this is such a long post :)