Some women experience heartburn or even have gastritis during pregnancy. Also the baby occupies a lot of space in the womb that stretches and make it a bit difficult to breathe which is normal during pregnancy. So firstly, don't eat too much all at once. Take small but frequent meals. You may want to stop any food that irritates you. Take a lot of fluids. If you find it too difficult to breathe or you are still experiencing difficulties, see a doctor.