Timing of menarche in Chinese girls with and without adolescent idiopathic scoliosis: current results and review of the literature.

Age at menarche is closely related to scoliosis progression during adolescence. Current data concerning the timing of menarche between scoliotic and non-scoliotic girls in the literature are conflicting, with inconclusive results. The aim of this study was to investigate the distribution difference of age at menarche for adolescent idiopathic scoliosis (AIS) girls and normal control population and to subsequently elucidate the menarche age difference through literature reviewing. Moreover, menarche age of AIS girls with Cobb angle <40°, 40-60°, >60° were compared to estimate its association with curve severity. Menstrual status data were available for 6,376 healthy female adolescents and 2,196 AIS girls. We notice that less than 10% of healthy Chinese girls experienced onset of menses before 11.38 years, and approximately 90% of healthy Chinese girls were menstruating by 13.88 years, with a median age of 12.63 years. As for AIS girls, less than 10% started to menstruate before 11.27 years, and approximately 90% were menstruating by 14.38 years, with a median age of 12.83 years. Average menarche age in AIS (12.83 ± 1.22 years) was significantly later than that of normal control girls (12.63 ± 0.98 years) (p < 0.001). Age at menarche for AIS affected girls was significantly greater than that of normal control girls at 75%, 90% of whom had attained menarche (p = 0.001, p < 0.001). Proportion of girls starting to menstruate after 14 years was significantly higher in AIS population compared with normal controls (16.3 vs. 8.1%, p < 0.001). In addition, AIS girls with Cobb angle >60° experienced onset of menses at an average age of 13.25 years, which was significantly later than AIS girls with Cobb angle <40° (12.81 years, p < 0.05) and marginally significantly later than AIS girls with Cobb angle between 40 and 60° (12.86 years, p = 0.053). In conclusion, a tendency of delayed onset of menarche was observed in Chinese idiopathic scoliotic girls in this large sample study, especially for girls with Cobb angle >60°, which is supported by multiple previously established positive linkages on AIS etiology studies. Accordingly it is believed that late menarche may contribute importantly to abnormal pubertal growth and subsequently modulate curve behavior in AIS.