Hello;
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Sorry there is no study available to document that red bull or any drink affects or creates any problem in pregnancy.So it is difficult to say how many times you can have it in a month.As such it should not affect but just in case you are worried please don;t have it instead you can have any other soft drink.
Thanks

Hi Lucky. Red Bull drink is claimed as an energy drink. Hence you may want to take it only when you are physically exhausted (such as during sports activities, unaccustomed exercise etc) or mentally exhausted (during exams, extra long driving may be). So taking it once in a while is not going to affect you for issues related to becoming pregnant years later. It contains caffeine as one of the main ingredients along with some other natural substances, amino acids etc. Caffeine acts as a stimulant to your brain making you feel better when you get exhausted. However, subjecting your body, ignoring its warnings such as tiredness, exhaustion etc, can be harmful sometimes. These drinks temporarily mask your mind's response to stress and exhaustion. Having it once in a while would be fine if you are physically a very healthy person. However during pregnancy or when ever one plans to conceive, its better to stay away from these drinks.