Nail growth rates do tend to decrease as we age and studies have shown statistically significant differences in growth rates before and after age 40. Anyone who has cared for young children has observed how much more frequently their nails require cutting. As we age and our nail growth rates slow, our nails are exposed to considerably more environmental influences and these exposures over time can affect the overall appearance and strength of our nails. In a normal-appearing nail, growth rates are not an index of personal health.
— Dana Stern, M.D. is a board-certified dermatologist specializing in nails. She works in private practice in New York City.