I recently went through a miscarriage at 6 weeks. I have a 3 year old, which we conceived naturally. Currently, I am 37, and endo (not sure what stage) and only one tube due to ectopic pregnancy previously. We went through a FET in June and the whole time I was preparing with omega-3 and EGGC supplements due to endo, but now I am worried that I perhaps *caused* my miscarriage due to taking EGCG. Is that possible? I read that is is like methotrexate chemically, so now I wonder if this could have all been avoided. I actually didn't stop taking EGCG (500 mg) supplement until a week or so after I found out i was pregnant. My doctor said the miscarriage was most likely chromosomally abnormal due to how early it occurred. She said we could hedge our bets and do a FET on the 1 remaining embyro we have left, thinking that it could be normal (since 50% of embryos are technically chromosomally abnormal at my age, 37), or start all over again with a fresh/frozen cycle and do PGS.
I did not tell my doctor of my supplementation with EGCG, mostly because I don't know if they could give me an answer about it. I know of the effects of caffeine and miscarriage, but this supplement was caffeine free. Now I worry that EGCG in general could hvae led to the miscarriage in and of itself! Could it be? So perhaps this was the chromosomally normal embryo and the one frozen isn't! Could I have just avoided all of this if I wasn't so stupid?!
This is a great question. Green tea can reduce the conversion of folic acid to methylfolate however it is nowhere near the strength of methotrexate - so the green tea having caused your miscarriage is highly unlikely. Think about the asian cultures who traditionally drink plenty of green tea and do not have any higher rate of miscarriage. Miscarriage rates are higher in endo patients, but also most miscarriages particularly if it's your first one, are related to random chromosomal abnormalities (aneuploidy). 
