It is generally safe for your wife to take a multivitamin like Zincovit postpartum, typically at a dosage of one tablet daily after a meal. However, her symptoms of weakness and weight loss four months after giving birth require a proper medical evaluation. While postpartum recovery takes time, these symptoms could also point to conditions like anemia or thyroid changes. Please encourage her to see her healthcare provider for a simple blood test before starting any supplement. This ensures she gets the exact care and correct duration of treatment she needs during this special postpartum period to keep both her and your baby healthy.