Welcome to HCM,
1) mcg and mg are very different and sometimes confused. The typical dose of
folic acid in
pregnancy is 400mcg. Five mg is unheard of. The statement about increased risk for
autism with very high doses of folic acid comes from a recent review finished in 2013. The study did show an increased risk for autism with an excessively high intake of folic acid which increased further if high B12 levels were added.2) A regular prenatal vitamin is what I recommend to my patients. There is no need for
vitamin E supplementation in pregnancy, it is a fat soluble vitamin so too much can be stored and build up in the fatty tissues.
For most water soluble
vitamins (B's included), excessive amounts are excreted in the urine. Mega doses are not included in this statement. The
DHA you speak of is an
essential fatty acid and is fine. A search of the literature showed that vitamin E supplementation is not needed or advised during pregnancy as I said earlier.
I do not know who is providing you advice, but the advice is unsafe and not supported by evidence as well as potentially harmful to the outcome. I highly suggest that if you do take a supplement, take a regular prenatal that meets 75% of the needs for a pregnant woman or 100%.
Recommended dietary intakes are put out by the US National Institutes of Health are are searchable for needs during pregnancy. You may access these and use as a guide when looking at prenatal labels.
Congratulations on your pregnancy and hope all is well. Kathy J. Shattler, MS,RDN