If Saturn is in the fourth house, there will be loss of mother. After the death of his mother, the native will get a step mother, but all these evil effects will not happen if Saturn is in his own house or exalted in the fourth house and the native will own prestigious conveyances like Cars, etc..
If Saturn in the fourth happens to be lord of the ascendant, the mother will be long-lived and the native will enjoy all kinds of comforts and be happy. If Saturn is associated with the lord of the 8th house, there will be loss of mother and happiness.
In the case of Aries, Taurus and Libra ascendants when Saturn will be a functional benefic being lord of the 10th and 11th , the 9th and 10th, and the 4th and 5th houses respectively, the disposition of Saturn in the 4th will give rise to powerful Dhana Yogas. Saturn in the fourth house will be in Kendra to the ascendant. His disposition in his own sign or in his sign of exaltation, will give rise to Sasa Yoga.
Other Views
Brihat Jatak- The person concerned will have no happiness and will be troubled in mind.
Phaldeepika- The native will be without house, conveyance, mother and happiness.
He will also be sickly in his childhood.