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1. Physical strain: pregnancy outcome and fertility Marja-Liisa Lindbohm
Finnish Institute of Occupational Health
2. Potential effects of physical strain Pronounced physical exertion may
alter hormonal balance
increase intraabdominal pressure
decrease uterine blood flow
affect nutritional status Moderate levels of maternal exercise is considered safe for both mother and fetus. Pronounced physical strain may however have adverse health effects. Strong physical effort can alter?
If it continues a log time, nutritional status might also be affected. All these are important determinants of fetal development and survival.Moderate levels of maternal exercise is considered safe for both mother and fetus. Pronounced physical strain may however have adverse health effects. Strong physical effort can alter?
If it continues a log time, nutritional status might also be affected. All these are important determinants of fetal development and survival.
3. Measures of physical work load in occupational reproductive studies Single factors
Heavy lifting and load carrying
Prolonged standing and/or walking
Bending and reaching
Energy expenditure, work intensity
Surrogate measures: job title, work duties In epidemiologic studies, several different measures of physical work load have been used.
Among the single factors? A few studies have used a scoring system in which estimated energy expediture for different work tasks are calculated together.In epidemiologic studies, several different measures of physical work load have been used.
Among the single factors? A few studies have used a scoring system in which estimated energy expediture for different work tasks are calculated together.
4. Working conditions and risk of preterm birth: a meta-analysis (Mozurkewich et al 2000)
5. Physically demanding work and adverse pregnancy outcome (Mozurkewich et al 2000)
6. Standing, lifting and having small-for-gestational-age infant (Fortier et al 1995)
7. Lifting, hectic work pace and pre-eclampsia (Wergeland et al 1997) Occasional lifting was related to an increased risk of pre-eclampsia, but no clear association between prolonged lifting and pre-eclampsia. Possibly, only trained women are employed in the jobs requiring physical fitness and therefore lifting is not harmful to these women.Occasional lifting was related to an increased risk of pre-eclampsia, but no clear association between prolonged lifting and pre-eclampsia. Possibly, only trained women are employed in the jobs requiring physical fitness and therefore lifting is not harmful to these women.
8. Prolonged standing and spontaneous abortion Inconsistent results on the effects of standing at work on the risk of spontaneous abortion
In two studies an increased risk for standing at work >8 hours/day was observed, but only in women who had a history of previous fetal loss
Cervical incompetence or other anatomical abnormalities or weakness may predispose these women to the effects of standing These women are more susceptible to the adverse effects work environment.These women are more susceptible to the adverse effects work environment.
9. Job strain and fertility (Hjollund et al 1998 and 2004) A follow-up study on couples trying to become pregnant
Job strain, defined as high job demands and low job control, had no substantial detrimental effect on fertility among women
Analysis restricted to couples with no suspected competitive causes of reduced fertility showed reduced fertility in women with high-strain jobs
No association found between any semen characteristics or sexual hormones and job strain
10. Recommendations Pregnant workers should avoid extremely heavy physical exertion (close to the individual's maximum capacity) in early pregnancy
During second and third trimester, it is wise to reduce the physical work load and ensure that there are enough rest periods
Continuous standing or walking during the whole workday should be avoided, at least in late pregnancy
Ahlborg, J Occup Environ Med 1995;37:943
11. EU guidelines on movements and postures (COM(2000) 466 final/2) Pregnant workers should not be exposed to
manual handling involving risk of injury
awkward movements and postures, especially in confined spaces
work at heights
long periods spent handling loads, or standing or sitting without regular exercise or movement to maintain healthy circulation EU guidelines, which are related to the EU directive on the safety and health at work of pregnant workers, give some guidance, how to deal with the risks related to movements and postures. EU guidelines, which are related to the EU directive on the safety and health at work of pregnant workers, give some guidance, how to deal with the risks related to movements and postures.
12. Guidelines on lifting weights (Denmark)(AT-anvisning Nr. 220.127.116.11, 1998) Manual handling of heavy loads may pose a risk to pregnancy
If the load weights more than 10-12 kg there should be a break between each lift and the total of lifted weights should not exceed 1000 kg during a day
From the beginning of the 7th month of pregnancy the weight of the lifted loads should be halved because of increasing lifting distance
13. Shift work and spontaneous abortion among midwives (Axelsson et al 1996)
14. Shift or night work and preterm birth: a meta-analysis (Mozurkewich et al 2000)
Six studies published in 1987 ? 1998
Pooled odds ratio 1.24 (95% CI 1.06 ? 1.46)
Analysis of three high-quality studies revealed also a weak association (OR 1.21, 95% CI 1.00 ? 1.47)
Conclusion: shift and night work may increase the risk of preterm birth
15. Shift work and fetal growth retardation Inconsistent results on the effects of shift work
Elevated risk of giving birth to SGA babies among mothers in shift work (Nurminen et al 1989)
Elevated risk of having a baby with low birth weight (<2500 g) among midwives in night work (Bodin et al 1999)
No excess of fetal growth retardation related to shift work or to evening or night work only (Fortier et al 1995)
16. Council Directive 92/85/EEC: night work Member States shall take necessary measures to ensure that a worker is not obliged to perform night work during her pregnancy and for a period following childbirth
A medical certificate stating that this is necessary for the safety or health of the worker is needed
Measures must entail the possibility of
transfer to daytime work
or leave from work or extension of maternity leave where such a transfer is not feasible
17. EU Guidelines on fatigue and working hours (COM(2000) 466 final/2) Because of increasing tiredness, some pregnant women may not be able to work irregular or late shifts, night work or overtime
Not all women are affected in the same way; the risks vary with the type of work and the individual
It may be necessary to adjust working hours temporarily, including the timing and frequency of rest breaks, and to change shift patterns and duration to avoid risks
EU guidelines describing the risk related to fatigue and working hours and guidance how ot deal with this risk.EU guidelines describing the risk related to fatigue and working hours and guidance how ot deal with this risk.
18. Noise and adverse pregnancy outcome Noise may increase maternal catecholamine secretion, which may further stimulate or retard uterine contractions and affect uteroplacental blood flow
Noise exposure of ?85dBL has been associated with fetal growth retardation
An excess of hormonal disturbances, infertility and spontaneous abortion also reported
EU Guidelines: pregnant workers should not be exposed to noise levels exceeding national limit values
19. EU Guidelines on some physical agents (COM(2000) 466 final/2) Pregnant workers should not
be exposed to prolonged excessive heat or cold
work in a high-pressure atmosphere or dive
be exposed to unpleasant vibration of the entire body, particularly at low frequencies
be exposed to work entailing shaking, shocks or where jolts or blows are delivered to the lower body
20. References on physical strain, shift work and reproductive health Mozurkewich EL, Luke B, Avni M, Wolf FM. Working conditions and adverse pregnancy outcome: a meta-analysis. Obstet Gynecol 2000;95:623-635.
Nurminen T. Shift work and reproductive health. Scand J Work Environ Health 1998;24:28-34.
Ahlborg G. Physical work load and pregnancy outcome. J Occup Environ Med 1995;37:941-944.