To the Editor Power and colleagues1 reported that 14 439 patients with bipolar disorder had an average of 1.48 children/person and that 81 295 with major depression had 1.78. Among 1975 patients in Sardinia,2 we recently found that patients with bipolar disorder (98.6% of whom were married) had an average of 1.69 children (women, 1.88; men, 1.36) whereas those diagnosed with major depression had 2.12 (women, 2.15; men, 2.04). Among patients with bipolar I disorder, we found an average of 1.69 (95% CI, 1.46-1.92) in women and 1.21 (95% CI, 0.96-1.46) in men, and among patients with bipolar II disorder, 2.06 (95% CI, 1.81-2.31) in women and 1.51 (95% CI, 1.23-1.79) in men. These findings indicate that fertility rates were consistently greater among women and ranked by diagnosis as unipolar disorder greater than bipolar II disorder greater than bipolar I disorder. Interestingly, Power et al found that the fertility rate ratio in their clinical sample compared with the general population of Sweden was 0.85 (95% CI, 0.84-0.87) among women and 0.75 (95% CI, 0.73-0.77) among men; in major depressive disorder, these ratios were not different from the general population of women and 0.93 (95% CI, 0.92-0.94) in men. Among Sardinian patients with mood disorder, this ratio to the general population of Sardinia was not significant (0.98 [95% CI, 0.93-1.02]) among women but 0.76 (95% CI, 0.69-0.83) in men.2 In both Sardinia and Sweden, reproductive rates in women with mood disorders were similar to those in the respective general populations, despite the different geographic and social environments involved. However, since fertility rates were 24% and 25% lower among men with bipolar disorder, both studies suggest that bipolar disorder may have less impact on interpersonal functioning in women than in men.