What is best heartburn remedy during pregnancy?

Simple tips. Ppis are effective. But if you take the following steps they should help as well. Dont eat less than 2 hours before lying down. Either raise the head of your bed six inches or sleep on 1 wedge pillow - dont sleep with multiple pillows as that can actually allow acid to come up to your throat. Avoid mint, caffiene, chocolate, spicy foods (i know its difficult to do but it will help -promise!).
PPI. Ppi or proton pump inhibitors are the best treatment for gerd in pregnancy. You can buy otc Prilosec or see your doctor to call in for you a generic prescription. Make sure though that if no one diagnosted before with gerd, you see a doctor first. Good luck!
Lifestyle changes. I agree with the changes in diet and lifestyle mentioned by the other doctors. Remember thr some ppis are safer for pregnancy than others. For example Omeprazole is class c while Pantoprazole is class b (safer). Zantac (ranitidine) is safe as well. Consult your ob.
Tumms. Putting a wedge under your bed and taking tumms work great.