Female predominance of PRCA in different age groups. Green and red bars represent the number of female and male patients, respectively. The number on the top of the green bar indicates the female-to-male ratio of the patients in each age group. The ratio was the highest in those <40 years old or in a child-bearing age group. The decreasing trend in the female-to-male ratio along with their increased age was statistically significant (P = .0485 with Cochran-Armitage test).