Previous studies in European and Asian women also pointed to associations between shift work and reduced ability to conceive, while other research hasn’t. Those with such positions were found to have fewer viable eggs, which can potentially make it harder for a woman to conceive.
To try to answer these questions, a research team led by Harvard TH Chan School of Public Health in Boston assessed the fertility of 473 women attending a fertility clinic.Researchers analyzed nearly 500 women who sought infertility treatment at Massachusetts General Hospital from 2004 to 2015.The effect was strongest in overweight women and those older than 37, the researchers said.Women with physically demanding jobs had a lower reserve of eggs than those whose work did not regularly require heavy lifting.As for how working non-day shifts may affect egg yields, it is speculated that it may have to do with circadian rhythm disruption, the researchers said.Researchers do not know why heavy lifting could affect a woman’s egg quality.
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The study conducted by Lidia Mínguez-Alarcón is only observational, so no official conclusions can be stated after the analysis, especially that more aspects of the occupational factors need to be addressed: night shifts versus day shifts or simply working long hours.Researchers tested the women’s ovarian reserve – the number of remaining eggs – and their levels of follicle stimulating hormone (FSH).The study was published online February 7 in the journal Occupational and Environmental Medicine.Nine in 10 worked normal office hours and 22% said their jobs were moderately to very physically demanding and 40% of women reported lifting or moving heavy objects at work.”And this is important because only the mature eggs are capable of developing into healthy embryos needed to sustain a pregnancy”. Women in the study who reported moving or lifting heavy objects at work were less educated on average than those who reported never doing so.”It is hard to hypothesise a mechanism by which a physically demanding job may have a negative effect on ovarian reserve, as the number of eggs (oocytes) is determined at birth and lost progressively throughout life, with smoking having been shown to be the main toxin that significantly diminishes ovarian reserve”, he said. The participants were surveyed about their work schedules and the physical demands of their jobs. In fact, they found that one in five middle-aged women who did shift work have at least three indicators of heart disease (like high blood pressure, obesity and metabolic syndrome).