In the name of Allah, the most Beneficent, the most Merciful, and all praise is due to Allah, Lord of all the creation.
And
The peace and blessings of Allah be upon our prophet Mohammed.
:Shaykh Uthaymeen, may Allah have mercy upon him said
The permissible excuses to break the fast are; the illness and the travel, as mentioned in the Quran & Sunnah. Among other excuses is that a woman is pregnant and she worries about herself or her baby to be put at risk. Another excuse is that a woman is breastfeeding and she worries about herself or her infant if she fasts. Another excuse is that a person needs to break his fast in order to save the life of the person who is under the protection of Islam as if he finds a drowning person in the sea, or someone who is surrounded on all sides by fire, and he needs to break his fast in order to save him, in that case he may break his fast with compliments. Another case if a person needed to break his fast in order to strengthen himself for jihad in Allaah’s sake, that would also be a permissible cause for him to break his fast, because the Prophet,peace and blessing of Allah be upon him said to his Companions, Allah satisfied with them in a foray of al Ftah:" You'll meet your enemy in the morning, and breaking the fast helps you save your strength, so break your fast". Muslim
So, if there is a permissible excuse for breaking the fast, and a person breaks his fast due to it, it isn't necessary for him to fast for the rest of the day. So, if it's become clear that person has broken his fast in order to save a person’s life who is under the protection of Islam that he continues breaks the fast. This is because he broke his fast due to a reason that permits him to break his fast, so it isn't necessary for him to fast in that case, because the prohibition of breaking fast on that day has been removed due to the permissibility to break his fast.
For that we say: the correct view in this matter, that If the patient feels well during the day and he was not fasting, it is not necessary for him to fast, and if a traveler back home during the day and he was not fasting, it isn't necessary for him to fast and if the woman's period ends during the day, it isn't necessary for her to fast. This is because all of these people broke their fasts for legitimate reasons on that day, because they are breaking their fast for a legitimate reason [in Sharea], so they aren't necessary to fast that day even If the reason to break fast has finished, all that due to excuse of Sharea.