Exploring associations of maternal exposure to ambient temperature with duration of gestation and birth weight: a prospective study

Li, Shenghui; Wang, Jiajia; Xu, Zhiwei; Wang, Xiaoyu; Xu, Gang; Zhang, Jun; Shen, Xiaoming; Tong, Shilu

doi:10.1186/s12884-018-2100-y

Table 4 Association of ambient temperature at conception/delivery with birth weight in Brisbane, 2000-2010 (n=237,585)

From: Exploring associations of maternal exposure to ambient temperature with duration of gestation and birth weight: a prospective study

	Birth weight, kg
	Crude		Adjusted
	Crude		Model 1		Model 2		Model 3^a/b
	β (95% CI)	P value	β (95% CI)	P value	β (95% CI)	P value	β (95% CI)	P value
In the first week
Maximum temperature
>30	0.010 (0.002, 0.017)	0.016	0.010 (0.004, 0.016)	0.001	0.005 (-0.004, 0.013)	0.265	0.004 (-0.006, 0.013)	0.447^a
25-30	0.011 (0.006, 0.016)	<.001	0.011 (0.007, 0.015)	<.001	0.005 (-0001, 0.011)	0.084	0.005 (-0.001, 0.011)	0.130^a
20-25	Ref		Ref		Ref		Ref
≤20	0.010 (-0.004, 0.025)	0.165	0.004 (-0.007, 0.015)	0.473	0.004 (-0.010, 0.016)	0.490	0.003 (-0.009, 0.015)	0.606^a
Minimum temperature
>20	0.016 (0.009, 0.022)	<.001	0.011 (0.006, 0.016)	<.001	0.008 (0.001, 0.017)	0.048	0.006 (-0.004, 0.016)	0.215^a
15-20	0.006 (0.001, 0.012)	0.033	0.006 (0.002, 0.011)	0.004	0.002 (-0.003, 0.008)	0.417	0.002 (-0.005, 0.008)	0.587^a
10-15	Ref		Ref		Ref		Ref
≤10	0.005 (-0.003, 0.013)	0.198	-0.001 (-0.007, 0.005)	0.761	0.002 (-0.004, 0.008)	0.550	0.002 (-0.005, 0.008)	0.601^a
In the first four weeks
Maximum temperature
>30	0.010 (0.002, 0.018)	0.020	0.012 (0.006, 0.019)	<.001	0.004 (-0.006, 0.014)	0.446	0.001 (-0.011, 0.011)	0.964^a
25-30	0.008 (0.003, 0.013)	0.002	0.009 (0.006, 0.013)	<.001	0.001 (-0.006, 0.007)	0.947	-0.001 (-0.008, 0.006)	0.826^a
20-25	Ref		Ref		Ref		Ref
≤20	0.010 (-0.017, 0.038)	0.472	0.005 (-0.016, 0.027)	0.642	0.005 (-0.016, 0.027)	0.645	0.003 (-0.020, 0.025)	0.822^a
Minimum temperature
>20	0.018 (0.012, 0.024)	<.001	0.011 (0.006, 0.016)	<.001	0.006 (-0.003, 0.015)	0.190	0.001 (-0.011, 0.012)	0.962^a
15-20	0.006 (0.001, 0.011)	0.049	0.007 (0.003, 0.011)	0.002	0.001 (-0.005, 0.008)	0.719	-0.001 (-0.008, 0.007)	0.901^a
10-15	Ref		Ref		Ref		Ref
≤10	0.008 (-0.001, 0.016)	0.057	-0.004 (-0.010, 0.003)	0.245	0.000 (-0.007, 0.007)	0.989	0.000 (-0.008, 0.008)	0.998^a
In the last week
Maximum temperature
>30	Ref		Ref		Ref		Ref
25-30	0.015 (0.007, 0.022)	<.001	0.010 (0.004, 0.016)	<.001	0.008 (0.002, 0.014)	0.014	0.006 (0.000, 0.013)	0.066^b
20-25	0.015 (0.008, 0.023)	<.001	0.014 (0.008, 0.020)	<.001	0.008 (-0.001, 0.017)	0.078	0.011 (0.008, 0.018)	0.041 ^b
≤20	0.025 (0.009, 0.041)	0.002	0.025 (0.013, 0.037)	<.001	0.016 (0.002, 0.030)	0.030	0.018 (0.010, 0.031)	0.024 ^b
Minimum temperature
>20	Ref		Ref		Ref		Ref
15-20	0.011 (0.005, 0.017)	<.001	0.004 (-0.001, 0.008)	0.141	0.002 (-0.003, 0.007)	0.488	-0.001 (-0.006, 0.006)	0.935^b
10-15	0.012 (0.005, 0.018)	<.001	0.009 (0.004, 0.014)	<.001	0.004 (-0.005, 0.013)	0.352	0.002 (-0.008, 0.011)	0.723^b
≤10	0.015 (0.007, 0.024)	<.001	0.012 (0.005, 0.018)	<.001	0.005 (-0.007, 0.017)	0.396	0.004 (-0.008, 0.016)	0.510^b
In the last four weeks
Maximum temperature
>30	Ref		Ref		Ref		Ref
25-30	0.008 (-0.001, 0.016)	0.070	0.007 (0.001, 0.013)	0.038	0.005 (-0.002, 0.012)	0.145	0.003 (-0.004, 0.011)	0.349^b
20-25	0.014 (0.006, 0.023)	<.001	0.016 (0.010, 0.023)	<.001	0.016 (0.006, 0.026)	0.002	0.013 (0.002, 0.024)	0.021 ^b
≤20	0.004 (-0.024, 0.033)	0.774	0.012 (-0.011, 0.034)	0.411	0.007 (-0.016, 0.031)	0.544	0.008 (-0.016, 0.033)	0.527^b
Minimum temperature
>20	Ref		Ref		Ref		Ref
15-20	0.011 (0.005, 0.017)	<.001	0.005 (0.001, 0.010)	0.033	0.004 (-0.002, 0.009)	0.177	0.001 (-0.005, 0.008)	0.703^b
10-15	0.014 (0.007, 0.020)	<.001	0.013 (0.008, 0.018)	<.001	0.011 (0.001, 0.020)	0.029	0.005 (-0.006, 0.016)	0.363^b
≤10	0.014 (0.005, 0.023)	0.003	0.013 (0.006, 0.020)	<.001	0.010 (-0.002, 0.023)	0.113	0.003 (-0.012, 0.018)	0.681^b

Model 1: adjusted for maternal age at delivery, indigenous status, maternal marital status, mode of labor onset, parity, baby’s gender, and duration of gestation
Model 2: further adjusted for relative humidity and air pressure around conception and delivery, along with all air pollutants (PM_10, O_3, NO_2, and SO₂) around conception and delivery
Model 3^a: model 2 adjustment plus calendar month at delivery, as well as maximum temperature and minimum temperature around delivery
Model 3^b: model 2 adjustment plus calendar month at delivery, as well as maximum temperature and minimum temperature around conception

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ISSN: 1471-2393

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