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Developmental Effects on Reproductive Function in Migrant Bangladeshi Women
Dr. Robert Chatterton (Northwestern University, USA)
Dr. Alejandra Nunez-de la Mora (Durham University)
Dr. Osul Choudhury (Sylhet Osmani Medical College, Bangladesh)
Data collection and analysis for this particularly project was completed in 2006 and we are currently engaged in publishing our findings. We examined the impact of growing up in either the UK or Bangladesh (where environmental conditions and particularly exposure to diseases differ greatly) on levels (measured in saliva) of the reproductive hormones, progesterone and oestrogen, in adult women. Subjects therefore included women still living in Bangladesh, women who migrated as children to the UK, adult migrants to the UK, second-generation Bangladeshis who grew up in the UK, and women of European descent living in the UK.
We found that progesterone levels and rates of ovulation differ significantly between these groups depending on where women had spent their childhood. Women who grew up in Sylhet, Bangladesh have significantly lower levels of progesterone and lower rates of ovulation as adults compared to Bangladeshi migrants and women of European descent who grew up in Britain. There is also a strong relationship between levels of progesterone and the number of years a girl spent in Britain prior to puberty, but the amount of time a Bangladeshi woman spent in Britain (if she migrated as an adult) had no impact on her level of salivary progesterone. Moreover, the average age at menarche (first menstruation) of child migrants was significantly earlier than the mean menarcheal ages of women still living in Sylhet, adult Bangladeshi migrants, and women of European descent.
We conclude from these findings that women “track” their environments during a critical and plastic period of growth during childhood and apportion reproductive effort (as illustrated through their hormonal levels) according to environmental signals read during this period. Our results conform to Life History Theory where it is argued individuals divide their energy between three functions: growth, maintenance, and reproduction. Where energy is constrained by environmental conditions (such as the challenges imposed by exposure to diseases or nutritional stress) there will be less energy available overall for these functions. Such constraints lead to trade-offs between the three functions.
Changing levels of hormones in women may have health implications. For example, higher levels of reproductive hormones in adult women appear to raise the risk for particular cancers such as breast cancer. Public health officials should therefore be aware of these possible changes in second-generation Bangladeshi migrants, particularly since South Asian women are generally considered to have lower risk for breast cancer compared to European women.
- Nunez-de-la-Mora, A. , Chatterton,R.T., Choudhury,O., Napolitano,D. & Bentley, G.R. (2007). Childhood conditions influence adult progesterone levels. PLoS Medicine 4(5): 813-821.
- Núñez-de-la-Mora, A., Chatterton, R.T., Mateo, E.T., Jesmin, F. & Bentley, G.R. (2007). Effect of chewing betel nut on measurements of salivary progesterone and estradiol. American Journal of Physical Anthropology 132(2): 311-315.