Ok, now that my DD is born I can say I truly believe that the large amounts of vitamin D kept me and her healthy. No preterm labor, no elevated blood pressure, nothing weird. I made it to 39 weeks! :D
I took 5000 IU (NOW brand), then another 1000 in my prenatal (New Chapter) and another 400 in my Calcium pill - so a total of 6400IU daily in my pregnancy - and 5 months of my pregnancy were in Wyoming winter, aka no sun (it might have been more D, my fishoil might have some too). I strongly believe the supplements contributed to a successful pregnancy. I wanted to add that New Chapter is to me the best prenatal - it has vitamin A as betacarotene only (safer), and folate only (no folic acid). It is truly worth it's money!