A migrant study of pubertal timing and tempo in British-Bangladeshi girls at varying risk for breast cancer.
BACKGROUND
Earlier menarche is related to subsequent breast cancer risk, yet international differences in the age and tempo of other pubertal milestones and their relationships with body mass index (BMI) are not firmly established in populations at differing risk for breast cancer. We compared age and tempo of adrenarche, thelarche, pubarche, and menarche in a migrant study of Bangladeshi girls to the United Kingdom (UK) and assessed whether differences by migration were explained by differences in BMI.


METHODS
Included were groups of Bangladeshi (n =168), British-Bangladeshi (n =174) and white British (n =54) girls, aged 5 to 16 years. Interviewer-administered questionnaires obtained pubertal staging; height and weight were measured. Salivary dehydroepiandrosterone-sulfate concentrations >400 pg/ml defined adrenarche. Median ages of pubertal milestones and hazard ratios (HR) with 95% confidence intervals (CI) were estimated from Weibull survival models.


RESULTS
In all three groups, adrenarche occurred earliest, followed by thelarche, pubarche, and finally menarche. Neither median age at adrenarche (Bangladeshi = 7.2, British-Bangladeshi = 7.4, white British = 7.1; P-trend = 0.70) nor at menarche (Bangladeshi = 12.5, British-Bangladeshi = 12.1, white British = 12.6; P-trend = 0.70) differed across groups. In contrast, median age at thelarche (Bangladeshi = 10.7, British-Bangladeshi = 9.6, white British = 8.7; P-trend <0.01) occurred earlier among girls living in the UK. Compared with Bangladeshi girls, HRs (95% CI) for earlier thelarche were 1.6 (1.1 to 2.4) for British-Bangladeshi girls and 2.6 (1.5 to 4.4) for white British girls (P-trend <0.01), but were attenuated after adjustment for BMI (British-Bangladeshi = 1.1 (0.7 to 1.8), white British = 1.7(1.0 to 3.1); P-trend =0.20).


CONCLUSIONS
Thelarche occurred earlier, but puberty progressed slower with increasing exposure to the UK environment; differences were partially explained by greater BMI. The growth environment might account for much of the ethnic differences in pubertal development observed across and within countries.
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA. houghtonlc@mail.nih.gov.
Lauren C
LC
Houghton
Department of Anthropology and Wolfson Research Institute for Health and Wellbeing, Durham University, Durham, UK. Gillian.cooper@dur.ac.uk.
Gillian D
GD
Cooper
Department of Anthropology and Wolfson Research Institute for Health and Wellbeing, Durham University, Durham, UK. g.r.bentley@dur.ac.uk.
Gillian R
GR
Bentley
School for Medicine, Pharmacy and Health, Durham University, Durham, UK. mark.booth@dur.ac.uk.
Mark
M
Booth
Sylhet MAG Osmani Medical College, Sylhet, Bangladesh. malwahouse@yahoo.com.
Osul A
OA
Chowdhury
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA. troisir@mail.nih.gov.
Rebecca
R
Troisi
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA. zieglerr@mail.nih.gov.
Regina G
RG
Ziegler
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA. hooverr@mail.nih.gov.
Robert N
RN
Hoover
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA. katkih@mail.nih.gov.
Hormuzd A
HA
Katki
D000293:Adolescent; D050499:Adrenarche / Q000378:metabolism*; D000367:Age Factors; D001459:Bangladesh / Q000208:ethnology; D001940:Breast / Q000254:growth & development*; D001943:Breast Neoplasms; D002648:Child; D002675:Child, Preschool; D019314:Dehydroepiandrosterone Sulfate / Q000032:analysis*; D054242:Emigrants and Immigrants; D005260:Female; D006801:Humans; D008572:Menarche; D016016:Proportional Hazards Models; D011627:Puberty; D012463:Saliva / Q000737:chemistry*; D013997:Time Factors; D006113:United Kingdom
D019314:Dehydroepiandrosterone Sulfate