Table 4.

Studies Examining Prolonged Standing and Pregnancy Issues

Author (Year)	Population Studied	Brief Summary
McDonald, et al., 1988a	56,067 Montreal women from 11 obstetrical units.	Elevated rate of spontaneous abortions for standing ≥ 8h/d for all occupations when grouped by work requirements. When broken down by occupation (managerial, health, and clerical), workers in clerical occupations had a sig. elevated risk (1.37 p < 0.01). Risk ratios were also elevated for stillbirths in workers standing ≥ 8h/d.
McDonald et al., (1988b)	22,761 Montreal single live births.	Did not find increased risk of preterm delivery or low birth weights from prolonged standing ≥ 8h/d.
Teitelman et al., (1990)	1.206 pregnant Connecticut women.	Standing on the job was sig. associated with increased preterm births (OR = 2.72, 95% CI = 1.24–5.95). Birth weights were reduced in the standing group, but the association was not sig. OR = 1.58, 95% CI = 0.51–4.94).
Klebanoff et al., (1990)	7,101 receiving prenatal care from NY, WA, OK, and TX+ LA clinical centers.	Prolonged standing ≥ 8h/d showed a moderate increased odds ratio of 1.31 (95% CI 1.10–1.71) for preterm delivery, but did not affect preterm delivery rates or birth weight.
Eskenazi et al., (1994)	1894 women (607 spontaneous abortions + 1287 live births. California.	Women standing > 8/d at work showed an increased adjusted odds ratio of 1.6 (95% CI 1.1–2.3) for spontaneous abortion when compared to standing 3h/d per day.
Henriksen et al., 1995a	8711 Danish women with single pregnancies.	Women who reported > 5 h/d of both standing and walking had an adjusted OR of 3.3 (95% CI 1.4–8.0) for preterm delivery when compared to women reporting ≤ 2 h/d of standing and walking. Standing only for 5 h/d when compared to ≤ 2 h/d of standing was not significant (OR = 1.2 95% CI 0.6–2.4).
Henriksen et al., 1995b	8711 Danish women with single pregnancies.	Women who reported standing at work > 5 h/d had birth weights 49g lower than women standing ≥ 2 h/d (95% CI −108 to 10). Higher birth weights were reported, however for women walking > 2 but ≤ 5 h/d (35g, 95% CI 8 to 63).
Mozurkewich et al., (2000)	160,988 women from Asian, European, and North American countries.	In a meta-analysis of 29 studies (case-control, cross- sectional, prospective cohort) involving 160,988 women, authors found that prolonged standing was sig. associated with an increased risk of preterm birth (OR = 1.26, 95% CI 1.13–1.40).
Ha et al., (2002)	1,222 Chinese women working at petrochemical plant.	Adjusting for confounders the association between maternal standing hours and reduced birth weight using a multivariate GAM model showed a sig. (P = 0.01) reduction of 16.8g.
Pompeii et al., (2005)	1,908 North Carolina pregnant women.	There were no sig. associations for preterm delivery outcomes or small birth size for gestational age birth (SGA) for pregnant women standing > 30h per week when compared to standing 6–15h per week.
Palmer et al., (2013)	Meta-analysis of articles from 1966–2011. 28 studies involved standing.	Preterm delivery median RR was 1.16 (1.00–1.35); small gestational age (SGA) median RR was 1.00 (0.93–126); low birth weight RR was 1.13 (0.70–1.58) with prolonged standing > 4h/d. Excess risks are low, but still exist.