Age of pubertal events among school girls in Lagos, Nigeria

BACKGROUND

Globally, there is a secular trend towards the reduced age for sexual maturity and menarche. This study aimed to determine the current age and factors associated with attainment of various stages of puberty in Nigerian girls.

METHODS

This study was a cross-sectional study involving 800 girls aged 6-15 years. The subjects were selected by stratified random sampling method from schools in Oshodi Local Government Area, Lagos State. They were interviewed and a physical examination was carried out to classify them into the various Tanner stages of breast and pubic hair maturational stages.

RESULTS

The median age of girls at first stage of breast maturation (B2), first stage of pubic hair development (PH2) and at menarche were 9.0, 9.0 and 12.0 years, respectively. Breast development was significantly related to normal nutritional status (adjusted odds ratio [AOR] 4.5, p<0.001), overweight (AOR 40.2, p<0.001), obesity (AOR 154.2, p<0.001) and upper social class (AOR 15.7, p<0.031). Pubic hair development was significantly related only to overweight (AOR 4.7, p<0.007) and obesity (AOR 15.7, p<0.001) while achievement of menarche was significantly related to overweight (AOR 0.1, p=0.005), obesity (AOR 0.1, p=0.0009), high social class (AOR 4.7, p<0.001) and being a member of the Hausa tribe (AOR 35.8, p<0.029).

CONCLUSIONS

There is decline in age of pubertal maturation of girls in Nigeria and the major contributory factors appear to be overweight and obesity. These findings are consistent with the pattern in developed countries.

Age at Pubertal Onset in Girls and Tobacco Smoke Exposure During Pre- and Postnatal Susceptibility Windows

BACKGROUND

Tobacco smoke contains known hormonally active chemicals and reproductive toxicants. Several studies have examined prenatal maternal smoking and offspring age at menarche, but few examined earlier pubertal markers, nor accounted for exposure during childhood. Our objective was to examine pre- and postnatal smoke exposure in relation to timing of early pubertal events.

METHODS

An ethnically diverse cohort of 1239 girls was enrolled at age 6-8 years old for a longitudinal study of puberty at three US sites. Girls participated in annual or semi-annual exams to measure anthropometry and Tanner breast and pubic hair stages. Prenatal and current tobacco smoke exposures, as well as covariates, were obtained from parent questionnaire. Cotinine was measured in urine collected at enrollment. Using accelerated failure time models, we calculated adjusted time ratios for age at pubertal onset (maturation stages 2 or higher) and smoke exposure.

RESULTS

Girls with higher prenatal (≥5 cigarettes per day) or secondhand smoke exposure had earlier pubic hair development than unexposed (adjusted time ratio: 0.92 [95% CI = 0.87, 0.97] and 0.94 [95% CI = 0.90, 0.97], respectively). Including both exposures in the same model yielded similar associations. Higher urinary cotinine quartiles were associated with younger age at breast and pubic hair onset in unadjusted models, but not after adjustment.

CONCLUSIONS

Greater prenatal and childhood secondhand smoke exposure were associated with earlier onset of pubic hair, but not breast, development. These exposures represent modifiable risk factors for early pubertal development that should be considered for addition to the extensive list of adverse effects from tobacco smoke.

Younger pubertal age is associated with allergy and other atopic conditions in girls

BACKGROUND

Early menarche is linked to higher incidence of adult asthma, suggesting that earlier puberty may influence type 2 immune response characteristics of allergic diseases. We examined the hypothesis that timing of breast and pubic hair development, which precede menarche, is associated with increased childhood atopic conditions.

METHODS

Girls were enrolled at 6-8 yr of age (2004-2007) in the Breast Cancer and the Environment Research Program Puberty Study and were followed through 2011. Pubertal stages were assessed and atopic conditions were queried annually. Associations of age at pubertal stage 2 for breast or pubic hair development with atopic conditions were assessed using prevalence ratios (PR) or odds ratios (OR) and 95% confidence intervals (CI) from log-binomial regression and generalized estimating equation models, controlling for body mass index and other covariates. A total of 1055 girls with medical and pubertal stage data were included.

RESULTS

Asthma (ever vs. never) was associated with younger pubarche (≤10 vs. >10 yr, PR = 1.15, CI: 1.04-1.28 adjusted for race/ethnicity and site; PR = 1.13, CI: 1.01-1.25 further adjusted for BMI), but not thelarche. In longitudinal models, risk of developing allergies increased with younger age at pubarche (adjusted OR = 1.60, CI: 1.10-2.34; ≤10 vs. >10 yr). Risks were highest among black girls with earlier pubarche (n = 248/326); for allergies, their fully adjusted OR was 2.35, CI: 1.06-5.19 for pubarche ≤10 vs. >10 yr.

CONCLUSIONS

Atopic conditions during childhood are associated with younger age at pubarche, independent of obesity, and these relationships may vary by racial/ethnic groups.