I have silver/gray hairs popping up! I know your body goes through some major changes during pregnancy, even if you don't actually feel or notice them all. Majority of these changes are caused by all the hormones from what I've read in my books and online...but hair changes too?!? REALLY?
One would think these prenatal vitamins would keep you above the game, but I guess if a growing baby is sucking all your nutrients from your body, then you're really just replacing what you've lost. So while my nails look fantastic and I'm feeling great my hair is "aging". It wouldn't be so bad, except that it's OTHER people who are noticing my grays, not me! I love being brunette, but it sure does nothing to hide these unsightly silvers.
According to Wikipedia hair color is the pigmentation of hair follicles due to two types of melanin: eumelanin and pheomelanin. If more melanin is present, the color of the hair is darker; if less melanin is present, the hair is lighter. Levels of melanin can vary over time causing one's hair color to change. Gray or white pigment is due to lack of pigmentation and melanin. Gray typically occurs as people age, for some at an early age and others later on. In some cases gray hair is caused by thyroid deficiencies and/or a vitamin B12 deficiency. The Journal of Investigative Dermatology published a study in 2005 which found that white people begin to gray in their twenties and early thirties while Asian people begin graying in their late thirties, and most of black skin tone retain their original hair color until their mid-forties.
So there ya have it! I'm getting old before I've even given birth :)