[Analysis of selected environmental and biophysical parameters during menarche]

It is challenging at the end of the 20th century to verify our concept of the secular trend in pubertal development, its pace, and role of environmental factors in the process. The study group consisted of patients visiting the Pediatric Gynecology Center in Szczecin, Poland. Retrospective analysis was based on 4386 cases recorded between 1975 and 1997. Participating in the prospective part of the study were 111 patients seen at the Center between 1994 and 1997 during the first 6 months after their first menstruation. The prospective group was divided into two groups according to gynecologic age: (1) up to three months and (2) between three and six months after menarche. The retrospective analysis was based on age, date of menarche, permanent residence (large town, small town, village), mother's menarcheal age, parents' education level and family status. In the prospective study, history was taken and the patients underwent standard physical examination. Additionally, school performance and number of siblings were recorded. The following parameters were studied: body mass, BMI, height, tertiary sex features. Ultrasonographic examinations were done with a 3.5 MHz transabdominal probe. Hormonal tests included blood concentrations of FSH, LH, E2 and PRL (basal and Metoclopramid-induced). Several correlations were studied, including menarcheal age and permanent residence, mother's and daughter's age at menarche, menarcheal age and parents' education, school performance, and family status. One standard deviation was taken as cut-off value for overweight and underweight groups. The maturity of tertiary sex features at the time of first menstruation was examined. Ultrasound was used to determine primary and secondary sex features. The study disclosed that menarche occurs most frequently in January and July (Table 1). A decline in the pace of pubertal development and narrowing of the urban-rural gap was observed (Tables 2-5). A significant correlation between the age at first menstruation in mothers and their daughters was observed (Table 6). Late menarche correlated with low level of paternal and especially maternal education, incomplete family status and poor school performance (Tables 7-9). At the time of menarche the mean body mass was 48 kg, mean height 159 cm, and tertiary sex features represented fourth, rarely third, stage. During six months after first menstrual blooding a significant increase in weight was noted, but there was no correlation between overweight and age at first menstruation (Tables 10-12). At the time of first menstruation the uterine body was already larger than the cervix (Table 13). In patients at the gynecologic age of 3 to 6 months after menarche there was a significant increase in the prolactin reserve (Table 14).

1. Analysis of the secular trend for the last two decades of the 20th century revealed no acceleration in pubertal development of girls. A reduction in environmentally-dependent differences in menarcheal age (urban vs. rural residence) was observed. 2. Marked influence of the environment (family and school factors) on the age at menarche was evidenced. 3. At the age of first menstruation, biophysical parameters (height, body mass, sex features, concentrations of hormones) revealed specific patterns but subtle individual differences remain.