Women who lift heavy loads at work may experience decreased fertility, and the effect appears stronger among overweight or obese women and older women, according to a new study from Harvard T.H. Chan School of Public Health.
Working non-daytime work schedules may also decrease fertility, the researchers found.
2017 Study Abstract
To explore whether work schedules and physically demanding work were associated with markers of ovarian reserve and response.
This analysis included women (n=473 and n=313 for ovarian reserve and ovarian response analysis, respectively) enrolled in a prospective cohort study of couples presenting to an academic fertility centre (2004–2015). Information on occupational factors was collected on a take-home questionnaire, and reproductive outcomes were abstracted from electronic medical records. Generalised linear models and generalised linear mixed models were used to evaluate the associations.
Occupational factors and markers of ovarian reserve and response among women at a fertility centre, BMJ, dx.doi.org/10.1136/oemed-2016-103953, 6 February 2017.
Women who reported lifting or moving heavy objects at work had 1.0 fewer total oocytes (p=0.08), 1.4 fewer mature oocytes (p=0.007) and 0.7 fewer antral follicles (p=0.06) compared with women who reported never lifting or moving heavy objects at work. The inverse association between heavy lifting and oocyte yield was stronger in women >37 years and with a Body Mass Index ≥25 kg/m2. Women who worked evening/night/rotating shifts had 2.3 (p<0.001) fewer mature oocytes, on average, compared with women who worked day-only shifts. None of the occupational exposures were associated with day 3 follicle-stimulating hormone or peak oestradiol levels.
Women working non-daytime shifts and those with physically demanding jobs had fewer mature oocytes retrieved after controlled ovarian hyperstimulation. Our results provide insight into possible mechanisms linking these occupational exposures with decreased fecundity.