Inna lillahi wa inna ilayhi raji’oon. To Allah we belong and unto Him we return. There is no word in the English language that I am aware of to describe a parent that has lost a child. There are many other words to describe other life and death situations:
A child that loses both of its parents is an orphan.
A woman that loses her husband is a widow.
A man that loses his wife is a widower.
The Prophet said, upon him be peace, “The miscarried child will pester its glorious and mighty Lord for His entering its two parents into the Fire until it is told, ‘O miscarried child that pesters its Lord! Enter your father and mother into Paradise.’ Then it will drag them with its umbilical cord until it makes them enter Paradise.” [Ibn Majah and Abu Ya`la from `Ali]
And again, “By the One in Whose hand is my soul, truly the miscarried child will certainly drag its mother with its umbilical cord to Paradise, provided one expects recompense [for sabr].” [Ibn Majah and Ahmad from Mu`adh]
And he said, upon him peace: “Your little ones are the larvas (da`aamees) of Paradise. They will meet their parents and grab them by their garments or their hands to no end other than that Allah will enter them into Paradise.” [Sahih Muslim]
IslamQA: Ruling on a Miscarried Fetus
SunniPath: Miscarriage – Loss of a Child
Karla Holloway: Giving a Name to the Pain of Losing a Child [The essay begins about 2 min 15 sec in so you can skip the first part]