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Heavy work and long hours in pregnancy have adverse effects

Obstetrics and gynaecology

Obstetrics and gynaecology

Women who do physically demanding jobs, shiftwork or work long hours are more likely to have babies who are small, low birthweight or are born prematurely, a prospective study has found.

A total of 676 women, with a singleton pregnancy, booking for hospital antenatal care in Ireland were studied. They were asked to complete a demographic and work detail questionnaire between 14 and 16 weeks' gestation. Outcome details were later extracted from case records. Four outcomes in particular were addressed: pre-term delivery (<37 weeks); birthweight <3,000g; birthweight <2,500g; and small for gestational age (SGA).

A regression analysis controlling for other known markers of adverse outcome as well as pregnancy complications such as antepartum haemorrhage was performed.

The authors found that working >40 hours per week, performing physically demanding work and having only a temporary contract were all associated with one or more of the four adverse outcomes. Women having two or more of these work patterns (e.g. long hours, plus shift or night working) had a much higher chance of low birthweight, preterm delivery or an SGA infant. For mothers with two or more adverse work patterns, the odds ratio for birthweight <2,500g was 4.65 (95% CI = 1.08-20.07) and for preterm birth 5.18 (95% CI = 1.0-27.01).

Adverse pregnancy outcome is strongly related to particular maternal demographics and behaviours, for example maternal age and parity, and smoking and alcohol consumption. This study suggests that the type of work done in early pregnancy may also confer risk.

The small sample size used in this study meant that statistical significance was not high. Also no data were collected on work pattern after the initial questionnaire was completed. These factors reduce the veracity of the trial's conclusions. Nevertheless, the findings are consistent with both the established literature and commonsense; if a pregnant woman's energies are directed heavily to working it can increase the likelihood of preterm and low birthweight babies. Interestingly, work stress appeared to have no effect on pregnancy outcome.

Niedhammer I, O'Mahony D, Daly S et al. Occupational predictors of pregnancy outcomes in Irish working women in the Lifeways cohort. BJOG 2009; DOI 10.1111/j.1471-0528.2009.01260.x

Reviewer

Dr Chris Barclay
GP, Sheffield

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