They say it's actually the core of the pineapple that works best, not the pineapple itself. It's an enzyme called Bromelain, you can also take tablets from the health food store, but I don't know if it would work as well. Some say it needs to be fresh pineapple, because it is an enzyme.
However, some say that fresh pineapple, if eaten in excess could cause a miscarriage, as it can cause uterine cramping. So if you are going to try it, it might be better to stick to the following routine:
Using Pineapple to Assist Implantation: Pineapple contains bromelain. Bromelain is a proteolytic enzyme that breaks up proteins that inhibit embryo implantation. Consuming a whole pineapple (focusing on the core as it has the highest concentration of Bromelain) during a fertility cycle can be beneficial.
For IVF [in vitro fertilization] cycle: one pineapple, divided into 5 portions - consume one portion each day, over five days, beginning on the day of your embryo transfer.
IUI [intra-uterine insemination] cycle: one pineapple, divided into 5 portions - consume one portion each day, over five days, beginning on the day of your IUI.
Timed intercourse cycle: one pineapple, divided into 5 portions - consume one portion each day, over five days, beginning on the day after ovulation.
Note: Be careful not to start consuming pineapple too early in the cycle. Beginning to consume pineapple BEFORE the recommended days above can actually affect your vaginal and cervical mucus PH, making it more acidic.