Firstly, Manna-C states specifically NOT to be used during pregnancy.
Secondly, certain foods can be dangerous when eaten excessively during pregnancy, so therefore an isolated substance from food also has the potential to be harmful and cannot just be disregarded as an issue because it is called food.
Thirdly, Phytobears have a totally different combination than Catalyst and therefore can't be used as an alternative.
Be careful to give accurate advice. These are good products, however they need to be used appropriately. There also appears to be a lack of evidence relating to pregnancy and the use of these products. By evidence I mean scientific, not just testimonial. Some people smoke all through pregnancy and end up with a healthy baby, but that doesn't mean it will happen for everyone.