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 exposures	N	β (95% CI)*	p Value	β (95% CI)*	p Value	β (95% CI)*	p Value
Total	3061
Mother lived on farm while pregnant
No	771	Referent		Referent		Referent
Yes	2250	−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
Missing	40
Mother performed farm activities while pregnant
No	940	Referent		Referent		Referent
Yes	1962	6.0 (−33.8 to 45.8)	0.77	−6.6 (−51.9 to 38.8)	0.78	0.3 (−0.3 to 1.0)	0.32
Missing	159
Mother worked with farm animals while pregnant
No	957	Referent		Referent		Referent
Yes	1863	−4.4 (−44.4 to 35.7)	0.83	−9.5 (−55.2 to 36.2)	0.68	0.2 (−0.5 to 0.8)	0.61
Missing	241
Family lived on farm when born
No	767	Referent		Referent		Referent
Yes	2259	−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
Missing	35
Farm animal exposure before age 3
No	822	Referent		Referent		Referent
Yes	1958	−1.8 (−43.4 to 39.8)	0.93	−9.1 (−56.6 to 38.3)	0.71	0.3 (−0.4 to 0.9)	0.46
Missing	281
Farm animal exposure before age 6
No	625	Referent		Referent		Referent
Yes	2314	3.5 (-42.2 to 49.2)	0.88	9.2 (-42.8 to 61.3)	0.73	0.01 (−0.7 to 0.7)	0.99
Missing	122
Breast fed
No	1057	Referent		Referent		Referent
Yes	1439	20.3 (−21.8 to 62.3)	0.35	20.1 (−27.7 to 67.9)	0.41	−0.2 (−0.8 to 0.5)	0.66
Missing	565
Indoor furry pets before age 6
No	2204	Referent		Referent		Referent
Yes	800	−7.3 (−47.6 to 33.1)	0.72	−34.7 (−80.6 to 11.2)	0.14	0.9 (0.2 to 1.5)	0.01
Missing	57
Mother smoked cigarettes when pregnant
No	2637	Referent		Referent		Referent
Yes	275	−25.1 (−87.5 to 37.3)	0.43	−11.6 (−82.8 to 59.7)	0.75	0.1 (−0.9 to 1.2)	0.77
Missing	149
Parents smoked cigarettes in house before age 6
No	1362	Referent		Referent		Referent
Yes	1611	−12.4 (−48.9 to 24.0)	0.50	−21.0 (−62.4 to 20.4)	0.32	0.4 (−0.2 to 1.0)	0.16
Missing	88
Raw milk
No	643	Referent		Referent		Referent
Yes	2246	49.5 (2.8 to 96.1)	0.04	66.2 (13.2 to 119.1)	0.01	0.4 (−0.4 to 1.1)	0.33
Missing	172

*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).