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 3 Association of ambient temperature at conception/delivery with duration of gestation 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

	Duration of gestation, weeks
	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	Ref		Ref		Ref		Ref
25-30	0.008 (-0.017, 0.033)	0.539	0.003 (-0.016, 0.021)	0.791	-0.005 (-0.025, 0.015)	0.598	0.000 (-0.020. 0.021)	0.982^a
20-25	0.007 (-0.018, 0.033)	0.572	0.023 (0.004, 0.043)	0.021	-0.006 (-0.034, 0.021)	0.664	0.009 (-0.021, 0.038)	0.571^a
≤20	0.026 (-0.026, 0.079)	0.322	0.031 (-0.009, 0.070)	0.135	-0.004 (-0.050, 0.041)	0.854	0.006 (-0.041, 0.052)	0.814^a
Minimum temperature
>20	0.026 (0.005, 0.046)	0.013	0.007 (-0.008, 0.023)	0.371	0.022 (0.003, 0.040)	0.020	0.029 (0.008, 0.049)	0.006 ^a
15-20	Ref		Ref		Ref		Ref
10-15	0.004 (-0.015, 0.023)	0.684	0.015 (0.001, 0.029)	0.040	-0.013 (-0.031, 0.007)	0.198	-0.018 (-0.038, 0.002)	0.082^a
≤10	0.033 (0.008, 0.058)	0.009	0.033 (0.014, 0.051)	<.001	-0.004 (-0.029, 0.022)	0.771	-0.010 (-0.038, 0.018)	0.481^a
In the first four weeks
Maximum temperature
>30	Ref		Ref		Ref		Ref
25-30	0.007 (-0.020, 0.034)	0.593	0.008 (-0.012, 0.029)	0.427	-0.003 (-0.025, 0.020)	0.822	0.013 (-0.011, 0.036)	0.305^a
20-25	0.014 (-0.014, 0.042)	0.320	0.030 (0.009, 0.051)	0.006	-0.010 (-0.042, 0.022)	0.529	0.020 (-0.017, 0.056)	0.288^a
≤20	0.054 (-0.041, 0.148)	0.265	0.037 (-0.034, 0.108)	0.310	-0.005 (-0.082, 0.072)	0.893	-0.008 (-0.086, 0.069)	0.833^a
Minimum temperature
>20	0.035 (0.014, 0.055)	0.001	0.015 (-0.001, 0.030)	0.063	0.032 (0.014, 0.051)	<.001	0.049 (0.026, 0.072)	<.001 ^a
15-20	Ref		Ref		Ref		Ref
10-15	0.007 (-0.012, 0.025)	0.470	0.018 (0.004, 0.032)	0.012	-0.010 (-0.031, 0.011)	0.338	-0.025 (-0.048, 0.001)	0.051^a
≤10	0.062 (0.036, 0.088)	<.001	0.056 (0.036, 0.075)	<.001	0.017 (-0.015, 0.049)	0.302	-0.003 (-0.039, 0.033)	0.882^a
In the last week
Maximum temperature
>30	Ref		Ref		Ref		Ref
25-30	0.019 (-0.007, 0.044)	0.148	-0.006 (-0.025, 0.013)	0.516	-0.003 (-0.022, 0.017)	0.796	0.009 (-0.012, 0.030)	0.412^b
20-25	0.006 (-0.020, 0.032)	0.669	-0.022 (-0.042, -0.002)	0.029	-0.013 (-0.042, 0.016)	0.380	0.003 (-0.028, 0.033)	0.866^b
≤20	0.002 (-0.049, 0.053)	0.934	-0.043 (-0.082, -0.005)	0.029	-0.033 (-0.080, 0.013)	0.160	-0.025 (-0.073, 0.023)	0.302^b
Minimum temperature
>20	-0.030 (-0.051, -0.009)	0.004	-0.010 (-0.025, 0.006)	0.223	-0.019 (-0.035, -0.002)	0.033	-0.042 (-0.061, -0.023)	<.001 ^b
15-20	Ref		Ref		Ref		Ref
10-15	-0.025 (-0.044, -0.007)	0.008	-0.024 (-0.038, -0.010)	<.001	-0.014 (-0.036, 0.008)	0.221	-0.004 (-0.027, 0.019)	0.732^b
≤10	-0.013 (-0.038, 0.012)	0.321	-0.023 (-0.042, -0.004)	0.019	-0.010 (-0.042, 0.022)	0.546	-0.005 (-0.038, 0.029)	0.777^b
In the last four weeks
Maximum temperature
>30	Ref		Ref		Ref		Ref
25-30	-0.002 (-0.029, 0.025)	0.891	-0.010 (-0.030, 0.011)	0.345	-0.009 (-0.031, 0.012)	0.399	0.002 (-0.022, 0.025)	0.878^b
20-25	-0.014 (-0.042, 0.014)	0.338	-0.035 (-0.056, -0.014)	0.001	-0.038 (-0.070, -0.005)	0.024	-0.022 (-0.058, 0.014)	0.224^b
≤20	-0.030 (-0.125, 0.066)	0.544	-0.038 (-0.110, 0.034)	0.302	-0.044 (-0.122, 0.033)	0.264	-0.031 (-0.110, 0.049)	0.449^b
Minimum temperature
>20	-0.022 (-0.042, -0.002)	0.034	-0.002 (-0.017, 0.014)	0.815	-0.003 (-0.021, 0.014)	0.715	-0.030 (-0.052, -0.008)	0.007 ^b
15-20	Ref		Ref		Ref		Ref
10-15	-0.028 (-0.046, -0.009)	0.003	-0.029 (-0.043, -0.016)	<.001	-0.039 (-0.062, -0.016)	0.001	-0.024 (-0.050, 0.001)	0.061^b
≤10	-0.021 (-0.047, -0.006)	0.008	-0.029 (-0.050, -0.008)	0.007	-0.043 (-0.078, -0.009)	0.014	-0.018 (-0.057, -0.004)	0.041 ^b

Model 1: adjusted for maternal age at delivery, indigenous status, maternal marital status, mode of labor onset, parity, baby’s gender, and birth weight
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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