For adults, fingernails grow at an average rate of about 1/10 of an inch per month, while they grow about 50 percent faster in children until they reach puberty. However, the rate of growth can be affected by a person's sex, level of health and the time of year.
Fingernails generally grow faster in men than they do in women. However, women's fingernails grow much faster than men's fingernails when they are pregnant, which is mostly due to an increase in hormones. The hormones released during pregnancy lead to a faster metabolism and increased circulation, which have the effect of making hair and nails grow faster.
Fingernails also grow faster during the summer than they do in the winter, although scientists are not sure exactly why. The nails on a person's dominant hand grow at a faster rate than those on the other hand, while nails on the longer fingers grow faster than the nails on the shorter fingers. So the nail on the middle finger grows fastest, while the nail on the pinky finger grows slowest. In addition, the rate of fingernail growth continues to slow down as a person ages, most likely due to age-related decreases in circulation and metabolism.