I have gained weight and worried about pregnancy-related problems due to excessive weight gain (toxemia), how can I prevent this?

Toxemia is a pregnancy-induced hypertension where a pregnant mother experiences a group of three or more symptoms. The signs and symptoms of toxemia may include elevated maternal blood pressure, swelling of ankles and hands, sudden weight gain as well as protein in urine. If you are experiencing any 2 of the above symptoms, you may possibly suffer from toxemia. Should this happens, please consult your gynecologist immediately.
The most important thing to prevent toxemia is to control your weight. From mid to final trimester of pregnancy, your appetite may increase. Processed food, fast food, high calorie and low nutrition food are highly not recommended. The weight gained during this period should not be more than 500g per week. You may control your weight by doing some exercises such as walking for at least 30 minutes a day. If you are fit enough, you may even do the usual household chores.
However, do consult your gynecologist before attempting to do any exercise or heavy household chores.