The Grey Head
Scholars have said that seeing a grey head for a man may indicate the birth of a child. For a woman, seeing her entire head grey might suggest her husband's immorality or his marriage to another if he is righteous, or that he will suffer sorrow because of her if he is not. Furthermore, a woman's black hair signifies her husband's love for her and the rectitude of his affairs.
Per Ibn Sirin's Muntakhab al-Kalam fi Tafsir al-Ahlam