Table 4.

Adjusted odds ratio estimates of the association between duration of EHE95/EHE90 and NTDs by climate region, NBDPS, 1997–2007

	South (AR, TX)	Southeast (NC, GA)	Northeast (NY)	Southwest (UT)	West (CA)	Upper Midwest (IA)	Overall NBDPS
	aOR (95% CI) *	aOR (95% CI) *	aOR (95% CI) *	aOR (95% CI) *	aOR (95% CI) *	aOR (95% CI) *	aOR (95% CI) *
EHE95
2 days vs 0	0.73 (0.37, 1.43)	1.15 (0.59, 2.23)	0.83 (0.24, 3.94)	0.85 (0.33, 2.18)	0.50 (0.21, 1.20)	1.02 (0.46, 2.27)	0.81 (0.58, 1.13)
3 days vs 0	0.92 (0.35, 2.41)	1.58 (0.52, 4.82)	3.28 (0.56, 19.13)	1.43 (0.40, 5.17)	0.56 (0.23, 1.39)	1.35 (0.43, 4.20)	1.16 (0.74, 1.82)
4 days vs 0	0.71 (0.18, 2.83)	0.76 (0.13, 4.44)	6.95 (0.57, 84.68)	1.21 (0.26, 5.67)	0.84 (0.29, 2.41)	2.25 (0.66, 7.70)	1.14 (0.64, 2.02)
EHE90
3 days vs 0	0.57 (0.26, 1.28)	0.70 (0.31, 1.60)	0.60 (0.15, 2.44)	1.42 (0.45, 4.49)	0.33 (0.12, 0.94)	1.12 (0.46, 2.77)	0.66 (0.45, 0.98)
4 days vs 0	0.26 (0.05, 1.37)	0.54 (0.14, 2.04)	2.44 (0.38, 15.92)	1.28 (0.25, 6.48)	0.53 (0.21, 1.34)	1.52 (0.51, 4.48)	0.77 (0.46, 1.28)
5 days vs 0	0.99 (0.46, 2.11)	1.56 (0.57, 4.29)	0.50 (0.02, 12.16)	0.84 (0.32, 2.19)	0.89 (0.42, 1.91)	1.54 (0.56, 4.22)	1.09 (0.74, 1.59)

^*Adjusted for maternal age, maternal race/ethnicity, and maternal body mass index (BMI)

EHE95 = extreme heat event defined as at least two consecutive days with daily universal apparent maximum temperature above the 95^th percentile of the universal apparent maximum temperature distribution for the summer season and for climate region; EHE90 = extreme heat event defined as at least three consecutive days with daily universal apparent maximum temperature above the 90^th percentile of the universal apparent maximum temperature distribution for the summer season and for climate region; NTDs = neural tube defects; aOR = adjusted odds ratio; CI = confidence interval; AR = Arkansas; TX = Texas; NC = North Carolina; GA = Georgia; NY = New York; UT = Utah; CA = California; IA = Iowa; NBDPS = National Birth Defects Prevention Study