Prolonged standing at work may harm fetal development

Robin Wulffson MD's picture
pregnancy, prolonged standing, physical exertion, fetal growth
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Many women continue working during their pregnancy and most who have jobs that do not require physical exertion can continue working throughout most of their pregnancy. Some jobs, however, require physical activity and/or prolonged standing; according to a new study, prolonged standing jobs may impact fetal development. Researchers in The Netherlands published the results of a study that evaluated fetal growth in relation to work-related factors online on June 27 in Occupational & Environmental Medicine.

The researchers noted that work-related risk factors, such as long work hours, and physically demanding work have been suggested to adversely influence pregnancy outcome. The authors designed a study 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.

The study group comprised 4,680 pregnant women recruited from 2002 through 2006 in The Netherlands. They were enrolled in a prospective study from early pregnancy onwards. Women who filled out a questionnaire during mid-pregnancy (response: 77% of enrolment) were included if they were gainfully employed and had a spontaneously conceived a pregnancy. Questions on physical workload were obtained from the Dutch Musculoskeletal Questionnaire; it contained questions regarding 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.

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The researchers found no consistent significant associations between either physically demanding work or working long hours in relation to small for gestational age, low birth weight, or preterm delivery. However, women exposed to long periods of standing had lower growth rates for fetal head circumference, resulting in a reduction of approximately 1 cm (3%) of the average head circumference at birth. Compared with women working more than 25 hours per week, women working 25–39 hours per week and women working more than 40 hours per week had lower growth rates for both fetal weight and head circumference, resulting in a difference of approximately 1 cm in head circumference at birth and a difference of 148–198 grams (5-7 ounces) in birth weight.

The authors concluded that long periods of standing and long working hours per week during pregnancy seem to negatively influence intrauterine growth.

Take home message:
Prolonged standing during pregnancy often causes low back pain during pregnancy; thus, most pregnant women try to avoid it. This study notes that in addition to maternal discomfort it may impact fetal growth. Thus, a pregnant women who has a job that requires prolonged standing should make every to reduce it. Larger companies may be able to provide an alternative position during pregnancy. If not, one might consider taking a disability leave during the pregnancy or seeking employment elsewhere. The most important job that every woman has is to make every effort to grow a healthy child.

Reference: Occupational & Environmental Medicine

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