Age at Menarche, Menstrual Characteristics and Associated Factors among Adolescent Girls in Indigenous Population in Niger Delta Region, Nigeria

Aim:Age atmenarchevaries among different populations, and isdependent on interaction between genetic and environmental factors. The aim of this study was to determine the age at menarche, menstrual characteristics and associated factors among adolescent girls in indigenous population in Niger Delta region, Nigeria.

Study Design: A cross-sectional study on 903 adolescent school girls from 6 secondary schools in Rivers state selected by multi-staged random sampling technique.

Place and Duration of Study: Indigenous ethnic populations in urban and rural (coastal rural and upland rural) areas in Rivers state were surveyed between April and June 2019.

Methodology: Data collected with questionnaire: menarcheal age, menstrual and demographic characteristics of participants.

Results: Age at menarche was12.10±1.37years, while urban area had11.62±0.13, coastal rural (11.69±0.04) and upland rural (13.24±0.10) years;with early menarche (10%) and delayed menarche (5%). Geographical area, ethnicity and fathers’ occupation significantly (P=0.001) influenced menarcheal age; with Ethnic groups: Ekpeye (12.96±1.36) >Ogoni (12.89±0.71) >Ikwerre (12.43±1.72) >Kalabari (11.69±0.99); Fathers’ occupation: Professionals/public servants (11.82±1.14) and fishing (11.75±0.94) < artisans/traders (12.02±1.36) and farming (12.69±1.45). Menstrual cycle length (days), was 28.04±1.57 (21-35), with majority (91.50%) having 26-30 days; and significantly different among geographical area (P=0.003), and ethnicity (P=0.001). Menstrual bleeding duration (days) was 4.55±1.03 (2-7), with majority (72.1%) having 4-5 days;and is statistically different according to geographical areas (P=0.001), ethnicity (P=0.001), and fathers’ occupation (P=0.14). Dysmenorrhoea was experienced by majority (56.6%) of subjects, and associated with increase in menarcheal age (P=0.01) and menstrual cycle length (P=0.001).

Conclusion: This study shows a low age at menarche, with earlier onset in urban and coastal rural areas than in upland rural areas. Ethnicity and geographical area, strongly influenced the menarcheal age and menstrual characteristics of subjects.