Disparities in the association between ambient temperature and preterm birth according to individual and regional characteristics: a nationwide time-stratified case-crossover study

Table 3 Association between ambient temperature during the last four weeks before delivery and preterm birth by greenness and medical resources in rural and urban area

	OR (95% CI)
	Rural	Urban
Enhanced vegetation index
Low	1.07 (1.00, 1.14)	1.03 (1.01, 1.06)
High	1.09 (1.01, 1.17)	1.02 (1.00, 1.05)
Park area per person
Low	1.04 (0.97, 1.11)	1.03 (1.01, 1.06)
High	1.09 (1.02, 1.16)	1.03 (1.00, 1.05)
OB/GYN specialists per 1,000 persons
Low	1.09 (1.00, 1.18)	1.03 (1.00, 1.05)
High	1.05 (0.99, 1.16)	1.03 (1.01, 1.06)
ER utilization rate within standard time
Low	1.07 (0.98, 1.15)	1.03 (1.00, 1.06)
High	1.06 (1.00, 1.13)	1.03 (1.00, 1.05)
DR utilization rate within standard time
Low	1.12 (1.04, 1.22)	1.03 (1.01, 1.06)
High	1.03 (0.98, 1.10)	1.02 (1.00, 1.05)

ORs were presented as those for 5℃ increase in moving averaged-temperature during the last four weeks before delivery. Urban and rural were categorized using median of population density. Greenness and medical resource indicators were categorized using median of each variable.
CI confidence interval, DR delivery room, ER emergency room, OB/GYN obstetrics and gynecology, OR odds ratio

ISSN: 1476-069X