Yeast Assassin is contraindicated during pregnancy because it contains Black Walnut and Wormwood. I wouldn't take it if I was trying to get pregnant, nor if I were nursing. I'll do some research on what to do if you have Yeast during pregnancy and get back with you on that subject... hopefully within a few days.
Both Wormwood and Black Walnut Hull are okay for kids under certain circumstances. You must be careful with age and dosage, though, so I couldn't recommend it unless you are under the counsel and care of an herbalist, naturopath or medical professional.
Yeast Assassin should be taken with Tummy Tune-Up probiotics. Tummy Tune-Up contains the 8 natural stomach bacteria, and it will strengthen and equip your gastrointestinal tract to function normally.
The length of time you take Yeast Assassin depends entirely upon your condition. I would take it until all signs of Yeast or Parasites (yes, it is good for getting rid of parasites as well) are gone for two weeks. If I felt I did have a yeast infection I would also stop ingesting any form of sweeteners and fermented, or yeasted foods for a two week period while taking the maximum dosage of Yeast Assassin and Tummy Tune-Up. Sugar and yeasty products are "food" for a yeast infection, and cutting off the "food" supply is a smart addition to taking the Yeast Assassin suppliment.
Taking a round of antibiotics is the BEST way to get a yeast infection. Avoid antibiotics if you can. Go for the garlic, goldenseal, and grapefruit seed extract treatment to deal with infections, if at all possible. I take garlic in capsules, or fresh. I also take goldenseal in tincture form, and grapefruit seed extract as 5 drops in juice three times a day for flu, cold, throat, and sinus infection. By being quick to treat myself before I'm very ill, I have succeeded in staying well.
Hope that helps...