Physically demanding work, fetal growth and the risk of adverse birth outcomes. The Generation R Study
- Claudia A Snijder1,2,
- Teus Brand3,
- Vincent Jaddoe1,4,5,
- Albert Hofman1,4,
- Johan P Mackenbach2,
- Eric A P Steegers6,
- Alex Burdorf2
- 1The Generation R Study Group, Erasmus Medical Center, Rotterdam, The Netherlands
- 2Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands
- 3Netherlands Centre for Occupational Diseases, Coronel Institute of Occupational Health, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
- 4Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- 5Department of Paediatrics, Erasmus Medical Center, Rotterdam, The Netherlands
- 6Department of Obstetrics and Gynaecology, Erasmus Medical Center, Rotterdam, The Netherlands
- Correspondence to Professor Alex Burdorf, Department of Public Health, Erasmus University Medical Centre, PO Box 2040, 3000 CA Rotterdam, The Netherlands;
Contributors CAS is guarantor. CAS was involved in the planning of the study, data collection, statistical analyses and interpretation of data and drafted the manuscript; AB contributed to the design of the study, supervision, interpretation of data and critical review of the manuscript; AH conceptionalised the Generation R study and participated in its design and conduction; EAPS, JPM and TB had critical input into the manuscript; VJ contributed to the design of the study, supervision, interpretation of data and critical review of the manuscript. All authors read and approved the final manuscript. All authors had full access to all of the data in the study. The hypothesis for this study arose before inspection of the data.
- Accepted 3 May 2012
- Published Online First 27 June 2012
Objectives Work-related risk factors, such as long work hours, and physically demanding work have been suggested to adversely influence pregnancy outcome. The authors aimed to examine associations between various aspects of physically demanding work with fetal growth in different trimesters during pregnancy and the risks of adverse birth outcomes.
Methods Associations between physically demanding work and fetal growth were studied in 4680 pregnant women participating in a population-based prospective cohort study from early pregnancy onwards in the Netherlands (2002–2006). Mothers who filled out a questionnaire during mid-pregnancy (response 77% of enrolment) were included if they conducted paid employment and had a spontaneously conceived singleton live born pregnancy. Questions on physical workload were obtained from the Dutch Musculoskeletal Questionnaire and concerned questions on lifting, long periods of standing or walking, night shifts and working hours. Fetal growth characteristics were repeatedly measured by ultrasound and were used in combination with measurements at birth.
Results There were no consistent significant associations between physically demanding work nor working hours in relation to small for gestational age, low birth weight or preterm delivery. Women exposed to long periods of standing had lower growth rates for fetal head circumference (HC), resulting in a reduction of approximately 1 cm (3%) of the average HC at birth. Compared with women working <25 h/week, women working 25–39 h/week and >40 h/week had lower growth rates for both fetal weight and HC, resulting in a difference of approximately 1 cm in HC at birth and a difference of 148–198 g in birth weight.
Conclusion Long periods of standing and long working hours per week during pregnancy seem to negatively influence intrauterine growth.
Funding This work was supported by financial support from the Erasmus Medical Centre, Rotterdam, the Erasmus University Rotterdam, the Netherlands Organization for Health Research and Development (ZonMw), the Netherlands Organisation for Scientific Research (NWO), the Ministry of Health, Welfare and Sport and the Ministry of Youth and Families. The present study was conducted in commission of the European project CONTAMED with funding from the European Union's Seventh Framework Programme (FP7) for Research and Technology Development [EU grant agreement 212502].
Competing interests None.
Patient consent Obtained.
Ethics approval Medical Ethics Committee at Erasmus University Medical Centre Rotterdam, The Netherlands (MEC 198.782/2001/31).
Provenance and peer review Not commissioned; externally peer reviewed.