Pregnancy is a time of bodily transformation; many minor problems can arise and be treated with simple remedies. Morning sickness (or sickness occurring during the day) usually begins around the 4th week and lasts until the 16th week. It has multiple causes: hormonal changes, low blood pressure, low blood sugar, allergies, poor diet, or anxiety. Edema is very common during pregnancy. Water leaks from the blood vessels into the surrounding tissues and causes swelling. The ankles and calves, in particular, are affected. Constipation is common during pregnancy. The pressure on the intestines hinders the evacuation of loose stools. Heartburn is caused by stomach fluid backing up into the esophagus. This heartburn is often accompanied by heartburn and acid reflux. Stretch marks sometimes appear as the body expands. Their severity can be reduced by applying aloe or olive oil to the affected areas to maintain skin elasticity.