You can use any brand of cough syrup as long as it says "EXPECTORANT" on it. This helps by making all the liquids in your body runnier including your cervical mucous which helps the sperm to survive longer and also makes the trip up to the egg easier for the sperm (does favour concieving boys as it just helps the already faster boy sperm to live longer and swim even faster). You take a dose 15 minutes to half hour before you have sex. Hope this helps:)
Iv done a bit of research into this method:)
Good luck, From Amber.
Amber, DS Bailey 09/03/04 & DS Astin 04/07/07