Research shows vitamin D plays a critical role in fertility, pregnancy outcomes, and lactation. Since the body can manufacture its own vitamin D through direct sunlight, I encourage my clients to spend about 20 to 30 minutes outside in direct sunlight. Because even non–chemical sunscreen blocks the rays needed to produce vitamin D, you should do this without any sunscreen. Spending just a few minutes in the sun daily can yield between 10,000 and 25,000 IU of vitamin D, which is plenty! (The ideal vitamin D level for a pregnant and breastfeeding woman is 60-80 ng/ml.)