Vitamin D is known to be an important part of our general health. Data now suggests it may play a role in fertility and success of treatments.
Sunlight is a natural source of Vitamin D, however during the long winter months with less sun exposure an added Vitamin D supplement may be suggested based on your levels.
See the link below to read about a meta-analysis published in the Journal of Human Reproduction relating to Vitamin D and its association to fertility treatment success.