Is reproductive health affected by a person's living conditions? Indiana University researchers have explored this issue in their latest research study.
Virginia J. Vitzthum, a senior scientist at the university's Kinsey Institute for Research in Sex, Gender, and Reproduction, says that when costs outweigh benefits, successful pregnancies are less likely to occur.
She has shown that during periods of intense labour and low food intake, rates of early pregnancy loss can more than double.
This is the first study to show seasonality of early pregnancy loss in a non-industrialized population-in this case rural Bolivian women -- and the first to demonstrate a relationship between economic activities and early pregnancy loss.
Vitzthum's research challenges the past belief that nearly all early pregnancy losses are caused by genetic defects in the embryo.
Given that genetic defects would not generally change with the seasons, Vitzthum's findings show that environmental factors must also play a major role in early pregnancy losses.
"This finding applies to U.S. moms just as much as Bolivians, and it applies to psychosocial resources just as much as food supply. As well as healthy food, pregnant women also need good working conditions and adequate social support from family, friends and workplace to keep their risks of early pregnancy losses low," Vitzthum said.
Men are also affected, with another research paper reporting a similar relationship between reproductive fitness and external influences.
"This paper also concerns the effects of limited resources, this time on male physiology. In the worst part of the year, late winter, testosterone levels are suppressed. This is particularly interesting because it had been thought that males were much less sensitive, if at all, to environmental conditions because they don't need a lot of energy for a pregnancy. The effects of poor resources on males appear to be more subtle but can still be important for their own health and well being," Vitzthum said.