New Delhi, Sept. 25 -- When a couple walks into my clinic after months or years of trying, they usually expect conversations about eggs, sperm, scans, and protocols. Rarely do they expect me to ask about a vitamin. Yet vitamin D is one of the first things I look at in women with Polyendocrine Metabolic Ovarian Syndrome (PMOS), and one of the first I want corrected before an IVF cycle begins. It isn't glamorous, and it isn't a miracle cure. But after four decades in reproductive medicine, I've learned that outcomes are often shaped by the quiet factors that get overlooked.

A deficiency hiding in plain sight

India is a sunny country, so vitamin D deficiency seems unlikely. In reality, indoor lifestyles, air pollution, clothing habits, dar...