I am so terribly sorry to hear of your loss.
Yes, I have, but happy to go over it again.
The data does NOT indicate that folic/folate causes twins. Researchers studied this phenomenon and concluded that it's much more likely that taking folic/folate simply enables both babies to survive and develop normally instead of becoming a vanishing twin which is really very common (and happened to me personally). We actually have kind of done a "study" on this ourselves on this site, where we find pink swayers (even without using Clomid) have far more twins than blue swayers even though blue swayers are taking MORE folic acid/folate. So I do not find that to be in any way a legit concern; if it were, we'd be seeing way more twins in our blue swayers than in our pink ones but we don't.
There are several studies that indicate that folic/folate PREVENT preterm birth and cerebral palsy among many other issues - NTDs, of course, but also possibly chromosomal abnormalities. Here are two:
https://www.ncbi.nlm.nih.gov/pubmed/19434228 https://www.ncbi.nlm.nih.gov/pubmed/26138063 I think it is misguided to fear folic/folate when it is the only supplement ever proven to prevent birth defects when taken before conception.
Many of us, myself included, were prescribed 4000-5000 mcg F/FA. The amount I recommend is a fraction of that and the reason why I do so is because I conceived a baby with a neural tube defect taking 800 mcg folic acid daily and eating a very healthy and varied diet (he is thankfully fine with only a minor NTD) So I have firsthand experience that even 800 is not enough and thus I recommend 1200-1600 since swayers are eating a more restricted diet.
There is some data that indicates high levels of folic acid in a mother's blood AT BIRTH may be linked to autism and also that taking high dose folic in the third tri But we wean off the f/FA months before that and additionally, the high levels in the blood are NOT NORMAL - the body should excrete folic acid and that it doesn't, means something is happening in the bodies of these women that is making them continue to store folic acid (and this can be done via diet and just a standard dose, not megadoses, since most people don't even take megadoses anyway) Plus, by taking folate, you prevent these concerns anyway as folate is better used by the body and doesn't get stored up the way folic acid does.
I hope this helps to alleviate your concerns. The SINGLE best thing you can do for a healthy pregnancy is to take folate or folic acid. If you have any reason to believe you have MTHFR or similar genetic mutation, take folate instead, but most people can tolerate folic acid just fine.