Before my fertility doctor screened me for vitamin D deficiency I had never heard of the importance of vitamin D to conceiving and maintaining pregnancy. When I was told I needed to take a vitamin D supplement I researched online and found that there does seem to be important when TTC. About a month and a half into taking the supplement, I got my BFP after 14 months of trying! I highly recommend anyone having trouble ask their doctor to test their vitamin D level tested. I wouldn't advise just taking the supplement without doctor supervision, I was told that it's possible to have too much. Good luck and baby dust!!!