Workplace Factors That Affect Women’s Ability to Conceive

A physically demanding job or work schedule outside of normal office hours may lower a woman's ability to conceive. The findings also showed that the quality of eggs were reduced by heavy lifting at work and evening, night or rotating shift patterns.

Previous studies that have linked occupational factors to fertility have measured in outcomes, such as, time of pregnancy and the ability to carry a pregnancy to full term.

But this is the first study to assess that a woman's biological capacity to have a baby may be influenced by workplace factors.

Study

The study involved 473 women attending one fertility clinic, whose average age of the women was 35, while their average BMI was 23.

They analyzed indicators of:

• Ovarian reserve - which represents the number of remaining eggs (antral follicle count)
• Levels of follicle stimulating hormone (FSH) - which rise as a woman ages and represent dwindling fertility
• Ovarian response - which are the number of mature eggs capable of developing into a healthy embryo in 313 of the women who had completed at least one cycle of IVF by December 2015

These women were all part of an ongoing (EARTH) study, which has been looking at environmental and dietary factors that might affect fertility since 2004.

The women were quizzed about the level of physical exertion required for their job and the hours and patterns worked, as well as leisure time physical and sedentary activities.

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Findings

The results showed that:

• 4 in 10 (40%) women said that their job required them to regularly move/lift heavy objects
• 1 in 4 (22%) said that their jobs were moderately to very physically demanding
• 9 in 10 (91%) said they worked during normal office hours

Ultrasound revealed that:

• The ovarian reserve or the number of remaining eggs ranged from 8 to 17 among all 473 women
• The average number of mature eggs retrieved from the 313 undergoing an IVF cycle was 9

Physically demanding jobs lowered the number of remaining eggs in women compared to women whose work did not require heavy lifting. But it did not seem to make any difference to FSH levels.

Physically demanding jobs reduced the total number of remaining eggs by 9% and number of mature eggs by nearly 14.5% in women who were undergoing IVF.

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Women working evening, night or rotating shifts had fewer mature eggs, on average, than those working normal shifts. This could be as a result of disruption to the body clock.

Overweight women (BMI of 25 and above) who had physically demanding jobs also had fewer mature eggs compared to those women if similar weight who did not have a physically demanding job

Older women (37 and above) also had only fewer mature eggs compared to younger women.

Conclusion

"These findings have clinical implications, as women with fewer mature oocytes would have fewer eggs which are capable of developing into healthy embryos," explain the researchers, who go on to add that the results "suggest that occupational factors may be more specifically affecting oocyte production and quality, rather than accelerating ovarian aging."

Being an observational study, no firm conclusions can be drawn on the causal relationship. Moreover, the researchers were unable to assess the impact of other potentially influential factors, such as long working hours or switching between day and night shifts.

"Taken together with our results, it appears that lower oocyte quality could be one pathway mediating the relationship between high frequency of moving or lifting heavy loads at work and reduced fecundity," the researchers suggest.

The research is published online in Occupational & Environmental Medicine.

Reference:

1. Lidia Mínguez-Alarcón et al. Occupational factors and markers of ovarian reserve and response among women at a fertility centre. Occupational & Environmental Medicine; (2017) doi.org/10.1136/oemed-2016-103953

Source-Medindia