All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Marrying a sick girl is permitted in the Sharee’ah. It is a good act and a great favor to the patient, and the person will be rewarded for it if he marries her with good intentions. However, marrying a healthy girl in order to have many healthy babies is desirable. The Prophet said: “Marry the affectionate fertile woman.” [Ahmad, the Hadeeth is sound]
However, if one is consulted for his advice about marrying a girl, he should inform the person about everything that could apparently affect the marriage. He does not have to tell him of minor defects as it may only cause disinclination and is not contrary to the purpose of marriage.
Allah knows best.