The effects of female reproductive cycle on metabolic rate Literature review

The effects of female reproductive cycle on metabolic rate - Literature review Example Much is known about the reproductive cycle and its effects on co-morbid conditions during normal function, the pathology of disease states specifically or indirectly affecting reproduction, and changes due to ageing. However, considerably less is understood about the effects of the reproductive cycle in healthy women on many individual factors, as this is their normal state and so there is no control against which to test, though there does exist some research into the differences in metabolism between healthy women with amenorrhoea and those with a regular reproductive cycle (Maughan 2000). No standard exists for the correct levels of bleeding at different ages, for example, which is becoming a fairly substantial public health issue (Harlow & Ephross 1995). However, this research hopes to quantify differences in individual women at different points in their own reproductive cycle, focusing specifically on changes in metabolism, rather than comparing the women as a group to some othe r standard. The hypothesis to be tested is that a woman's point in the reproductive cycle will have an effect on resting and post-exercise metabolism; the null hypothesis being used is that it will not have an effect. Declining conception rates combined with an increase in obesity among women of childbearing age make this research important to the future of reproductive medicine; it is vital that the connection between metabolism and reproduction is fully understood (Crain et al. 2008). In order to achieve this, metabolic rates will be measured at rest and after exercise using expired gas analysis weekly for four weeks. This timing has been chosen to ensure that a sample is taken during or close to each of the four stages of the reproductive cycle. These are the menstruation phase, the follicular phase, the ovulatory phase, and the luteal phase (Porter 2009). The different length of time for each phase in individual women make it extremely difficult to ensure samples are taken durin g each phase, but the day within the cycle can be monitored so that the data can be corrected for this factor. Additionally, algorithms do exist to monitor an individual's reproductive cycle and measure at which point a particular woman is in her cycle, allowing careful recording of this related data (Wactawski-Wende et al. 2009). Each of these phases has a different effect on the woman experiencing them. The menstruation phase, which traditionally marks the start of the next reproductive cycle, is the period of time during which the uterine wall is shed in response to a reduction in oestrogen and progesterone levels. Bleeding occurs, though usually only in a volume of about fifteen to seventy-five millilitres. Menstruation actually during the â€Å"next† phase of the cycle, the follicular phase, though they are being considered separately for purposes of this research. During this follicular phase, there is an increase in follicle-stimulating hormone, which causes several fo llicles to begin to grow in preparation for releasing an ovum, or egg cell. This follicle then begins to produce oestrogen, of which levels peak at the ovulation phase. The ovulation phase is the point where the ovum is released from the follicle and is precipitated by a surge in both lutenizing and follicle-stimulat