Rashi on Numbers 5:28/רש"י על במדבר ה׳:כ״ח

1ואם לא נטמאה האשה AND IF THE WOMAN WAS NOT DEFILED on the occasion of this secluding herself with this man,

2וטהרה הוא AND BE CLEAN (guiltless) as regards any other place,

3ונקתה THEN SHE SHALL BE FREE from the effect of the water that waste the body and not only this, but ונזרעה זרע SHE SHALL CONCEIVE SEED — i.e. if until now she used to bear children in pain, she will from now bear with ease (free from pain), if up to now she used to bear black (ugly) children, from now on she will bear white (beautiful) children (Sifrei Bamidbar 19; Sotah 26a).