Table 2.
Summary statistics of individual-experienced heatwaves in the last gestational week for the study population in the warm season (May-September), 2008–2018.
| Heatwave | Definitions | Cut-off heat index values | Total Subjects experiencing heatwaves (n, %) a | Total Subjects experiencing > 1 heatwaves (n, %) b | Non-PROM experiencing heatwaves (n, %) | PROM experiencing heatwaves (n, %) |
|---|---|---|---|---|---|---|
|
| ||||||
| HWD1 | Heat index > 75th percentile lasting for ≥ 2 days | 32.8 °C | 49,518 (25.96) | 3,470 (1.82) | 44,909 (25.77) | 4,615 (27.99) |
| HWD2 | Heat index > 75th percentile lasting for ≥ 3 days | 32.8 °C | 34,522 (18.10) | 417 (0.22) | 31,230 (17.92) | 3,292 (19.96) |
| HWD3 | Heat index > 75th percentile lasting for ≥ 4 days | 32.8 °C | 22,997 (12.06) | – | 20,728 (11.89) | 2,269 (13.76) |
| HWD4 | Heat index > 90th percentile lasting for ≥ 2 days | 35.6 °C | 17,822 (9.34) | 738 (0.39) | 16,031 (9.20) | 1,791 (10.86) |
| HWD5 | Heat index > 90th percentile lasting for ≥ 3 days | 35.6 °C | 10,253 (5.37) | 86 (0.05) | 9,219 (5.29) | 1,034 (6.27) |
| HWD6 | Heat index > 90th percentile lasting for ≥ 4 days | 35.6 °C | 5,679 (2.98) | – | 5,076 (2.91) | 603 (3.66) |
| HWD7 | Heat index > 95th percentile lasting for ≥ 2 days | 37.8 °C | 5,690 (2.98) | 141 (0.07) | 5,075 (2.91) | 615 (3.73) |
| HWD8 | Heat index > 95th percentile lasting for ≥ 3 days | 37.8 °C | 2,772 (1.45) | 23 (0.01) | 2,508 (1.44) | 264 (1.60) |
| HWD9 | Heat index > 95th percentile lasting for ≥ 4 days | 37.8 °C | 1,404 (0.74) | – | 1,274 (0.73) | 130 (0.79) |
| HWD10 | Heat index > 98th percentile lasting for ≥ 2 days | 40.0 °C | 1,282 (0.67) | 73 (0.04) | 1,148 (0.66) | 134 (0.81) |
| HWD11 | Heat index > 98th percentile lasting for ≥ 3 days | 40.0 °C | 624 (0.33) | 10 (0.01) | 549 (0.32) | 75 (0.45) |
| HWD12 | Heat index > 98th percentile lasting for ≥ 4 days | 40.0 °C | 339 (0.18) | – | 303 (0.17) | 36 (0.22) |
Abbreviation: PROM, premature rupture of membranes; HI, heat index; °C, degree Celsius.
a
Number of mothers with and without PROM who experienced at least one heatwave event in the last week of pregnancy.
b
Number of mothers with and without PROM who experienced two or more heatwave events in the last gestational week. Based on the definitions of HWD3, HWD6, HWD9, and HWD12, mothers will not experience more than one heatwave using these four definitions during the last gestational week.