Table 2

Associations between maternal occupational exposure to physically demanding work during pregnancy with the risk of adverse birth outcomes in the Generation R Study

Physically demanding work	N	SGA (n=201)		Preterm birth (n=231)		Low birth weight (n=203)
Physically demanding work	N	OR (95% CI) unadjusted	OR (95% CI) adjusted^†	OR (95% CI) unadjusted	OR (95% CI) adjusted^†	OR (95% CI) unadjusted	OR (95% CI) adjusted^‡
Long periods of standing
No	2435	Reference	Reference	Reference	Reference	Reference	Reference
Occasionally	918	1.49 (1.06 to 2.11)^*	1.34 (0.94 to 1.92)	0.83 (0.57 to 1.20)	0.78 (0.53 to 1.15)	1.20 (0.84 to 1.73)	1.65 (1.02 to 2.64)^*
Often	881	1.04 (0.70 to 1.54)	0.95 (0.63 to 1.45)	1.03 (0.72 to 1.46)	0.95 (0.65 to 1.40)	1.00 (0.68 to 1.47)	1.02 (0.60 to 1.73)
Long periods of walking
No	2129	Reference	Reference	Reference	Reference	Reference	Reference
Occasionally	1461	1.19 (0.86 to 1.65)	1.09 (0.78 to 1.53)	1.12 (0.83 to 1.53)	1.07 (0.78 to 1.46)	1.16 (0.84 to 1.60)	1.08 (0.70 to 1.67)
Often	664	1.40 (0.94 to 2.08)	1.22 (0.79 to 1.89)	0.96 (0.63 to 1.46)	0.85 (0.54 to 1.33)	0.96 (0.61 to 1.50)	0.86 (0.46 to 1.60)
Lifting >25 kg
No	3981	Reference	Reference	Reference	Reference	Reference	Reference
Occasionally	217	2.11 (1.27 to 3.50)^*	2.41 (1.43 to 4.08)^*	1.26 (0.71 to 2.25)	1.26 (0.70 to 2.26)	1.21 (0.65 to 2.25)	1.31 (0.60 to 2.85)
Often	70	1.79 (0.71 to 4.51)	1.85 (0.70 to 4.88)	0.58 (0.14 to 2.39)	0.55 (0.13 to 2.28)	1.01 (0.32 to 3.25)	1.86 (0.44 to 7.77)
Nightshifts
No	4069	Reference	Reference	Reference	Reference	Reference	Reference
Occasionally	137	1.74 (0.90 to 3.37)	1.69 (0.86 to 3.33)	0.90 (0.39 to 2.07)	0.87 (0.38 to 2.01)	1.04 (0.45 to 2.39)	1.78 (0.64 to 4.96)
Often	60	0.76 (0.19 to 3.15)	0.73 (0.17 to 3.08)	1.41 (0.51 to 3.92)	1.29 (0.46 to 3.65)	1.62 (0.58 to 4.52)	1.23 (0.28 to 5.41)
Work hours
1–24 h/week	1191	Reference	Reference	Reference	Reference	Reference	Reference
25–39 h/week	2214	1.38 (0.94 to 2.02)	1.19 (0.79 to 1.77)	1.44 (1.01 to 2.05)^*	1.29 (0.89 to 1.87)	1.51 (1.03 to 2.21)^*	1.25 (0.75 to 2.09)
>40 h/week	1084	1.65 (1.09 to 2.52)^*	1.29 (0.81 to 2.05)	1.58 (1.06 to 2.35)^*	1.32 (0.85 to 2.03)	1.73 (1.14 to 2.64)^*	1.20 (0.66 to 2.18)

↵* p Value <0.05.
↵† Adjusted for maternal age, height at intake, weight before pregnancy, educational level, ethnicity, parity, smoking, alcohol use, folic acid supplement use, self-perceived health and fetal gender.
↵‡ Adjusted for maternal age, height at intake, weight before pregnancy, educational level, ethnicity, parity, smoking, alcohol use, folic acid supplement use, gestational age at birth, self-perceived health and fetal gender.