All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
If a pregnant or a suckling woman fears being affected by fasting, then she is permitted to break her fast and make up for the missed days later on. They are treated just like the sick person. To clarify, a pregnant or suckling woman is allowed to break the fast if they fear that a sickness would occur to them if they fasted, or if they are already sick and they fear that their fasting would worsen their condition. However, pregnant and suckling women are not allowed to break the fast because of suffering from of slight headache or pain or normal vomiting that does not cause harmful fatigue.
One of the cases in which breaking the fast is allowed in Ramadan is that of sickness because of which fasting may seriously affect one’s body. For example, one is not allowed to fast if one has a sickness that will cause one to lose his sight or hearing if he insists on fasting. Also, the Muslim is allowed to break his fast if he is sick and he most likely believes that fasting would delay his recovery. Such cases should be judged by a doctor who is Muslim and trustworthy. This is also valid when there is a strong possibility of harm. Allah Almighty says (what means): {So fear Allah as much as you are able.} [Quran 64: 16]
Allaah Knows best.