Table 1

Associations between early-life farm exposures and pulmonary function in the Agricultural Lung Health Study, 2009–2013

FEV1 (mL)FVC (mL)FEV1/FVC (%)
Early-life exposuresNβ (95% CI)*p Valueβ (95% CI)*p Valueβ (95% CI)*p Value
Total3061
Mother lived on farm while pregnant
 No771ReferentReferentReferent
 Yes2250−16.6 (−59.1 to 26.0)0.45−11.7 (−60.1 to 36.6)0.63−0.6 (−1.2 to 0.1)0.11
 Missing40
Mother performed farm activities while pregnant
 No940ReferentReferentReferent
 Yes19626.0 (−33.8 to 45.8)0.77−6.6 (−51.9 to 38.8)0.780.3 (−0.3 to 1.0)0.32
 Missing159
Mother worked with farm animals while pregnant
  No957ReferentReferentReferent
  Yes1863−4.4 (−44.4 to 35.7)0.83−9.5 (−55.2 to 36.2)0.680.2 (−0.5 to 0.8)0.61
  Missing241
Family lived on farm when born
 No767ReferentReferentReferent
 Yes2259−19.7 (−62.3 to 23.0)0.37−11.8 (−60.2 to 36.7)0.63−0.6 (−1.3 to 0.05)0.07
 Missing35
Farm animal exposure before age 3
 No822ReferentReferentReferent
 Yes1958−1.8 (−43.4 to 39.8)0.93−9.1 (−56.6 to 38.3)0.710.3 (−0.4 to 0.9)0.46
 Missing281
Farm animal exposure before age 6
 No625ReferentReferentReferent
 Yes23143.5 (-42.2 to 49.2)0.889.2 (-42.8 to 61.3)0.730.01 (−0.7 to 0.7)0.99
 Missing122
Breast fed
 No1057ReferentReferentReferent
 Yes143920.3 (−21.8 to 62.3)0.3520.1 (−27.7 to 67.9)0.41−0.2 (−0.8 to 0.5)0.66
 Missing565
Indoor furry pets before age 6
 No2204ReferentReferentReferent
 Yes800−7.3 (−47.6 to 33.1)0.72−34.7 (−80.6 to 11.2)0.140.9 (0.2 to 1.5)0.01
 Missing57
Mother smoked cigarettes when pregnant
 No2637ReferentReferentReferent
 Yes275−25.1 (−87.5 to 37.3)0.43−11.6 (−82.8 to 59.7)0.750.1 (−0.9 to 1.2)0.77
 Missing149
Parents smoked cigarettes in house before age 6
 No1362ReferentReferentReferent
 Yes1611−12.4 (−48.9 to 24.0)0.50−21.0 (−62.4 to 20.4)0.320.4 (−0.2 to 1.0)0.16
 Missing88
Raw milk
 No643ReferentReferentReferent
 Yes224649.5 (2.8 to 96.1)0.0466.2 (13.2 to 119.1)0.010.4 (−0.4 to 1.1)0.33
 Missing172
  • *Estimates represent the difference in mean response (FEV1 and FVC in millilitres and FEV1/FVC as a percent) between a subject who experienced the exposure and one who did not, holding all covariates constant. Covariates were selected based on previous research on modelling pulmonary function and Agricultural Lung Health Study analyses and included age, age2, gender, race, state (Iowa or North Carolina), height, height2, smoking status, pack-years, asthma status, and for FVC, weight. CIs were calculated as the beta coefficient plus or minus 1.96 times the standard error (β ±1.96×SE).