Table 1. Characteristics and Use of Empirical Antibiotic Therapy in Included Studies^a.

Source	Location	Setting	Design	Births, No.	Included	EOS Calculator		Conventional Strategy			Reduction in Empirical AB
						No.	Empirical AB, No. (%)	Strategy	No.	Empirical AB, No. (%)	Absolute %	Relative Risk, % (95% CI)
Before-After Analysis
Kuzniewicz et al,15 2017	United States	Mixed	Prospective	204 485	GA ≥35 wk	56 261	1698 (3.0)	CDC informed	95 543	5226 (5.5)	2.5	55.2 (52-58)
Achten et al,26 2018	The Netherlands	Regional	Retrospective and prospective	3953	GA ≥35 wk	1877	51 (2.7)	National guideline informed	2076	100 (4.8)	2.1	56.4 (40-79)
Dhudasia et al,27 2018	United States	Tertiary	Retrospective and prospective	11 782	GA ≥36 wk	6090	222 (3.6)	CDC and AAP informed	5692	356 (6.3)	2.6	58.3 (49-69)
Strunk et al,28 2018	Australia	Tertiary	Prospective	4233	GA ≥35 wk	2502	206 (8.2)	Adaptation AAP guideline	1732	237 (13.7)	5.5	60.2 (50-72)
Hypothetical Database Analysis
Gievers et al,29 2018	United States	Tertiary	Retrospective and prospective	9039	Chorioamnionitis, GA ≥35 wk	143	13 (9.1)	CDC informed	213	203 (95.3)	86.2	9.5 (6-16)
Beavers et al,30 2018	United States	Tertiary	Retrospective	NR	Chorioamnionitis, GA ≥35 wk	76	28 (36.8)	Preimplementation	180	168 (93.3)	57.0	39.3 (29-53)
Shakib et al,31 2015	United States	Tertiary	Retrospective	20 262	Chorioamnionitis, well-appearing, GA ≥34 wk	698	39-86 (5.6-12.3)b	Actual practice (CDC and CFN informed)	NA	430 (61.6)	49.3-56.0b	9.1-20.0b
Kerste et al,32 2016	The Netherlands	Regional	Retrospective	2094	AB for suspected EOS, GA ≥34 wk	108	51 (47.2)	Actual practice (national guideline informed)	NA	108 (100)	52.8c	47.2 (39-58)c
Warren et al,33 2017	United States	Tertiary	Retrospective	NR	AB for suspected EOS, GA ≥34 wk	202	47 (23.3)	CDC guideline	NA	188 (93.1)	69.8c	25.0 (19-32)c
Money et al,34 2017	United States	Tertiary	Retrospective	19 525	Chorioamnionitis, well-appearing for 24 h, GA ≥35 wkc	362	9 (2.5)	Current protocol (CDC and AAP informed)	NA	361 (99.7)d	97.2d	2.5 (1-5)d
Carola et al,35 2018	United States	Tertiary	Retrospective	17 908	Chorioamnionitis, GA ≥35 wk	896	209 (23.3)	Actual practice (AB if chorioamnionitis)	NA	896 (100)	76.7	23.3 (21-27)
Joshi et al,36 2019	United States	Tertiary	Retrospective	10 002	Chorioamnionitis, well-appearing at birth, GA ≥34 wk	596	53 (8.9)	Institutional practice (AB if chorioamnionitis)	NA	596 (100)	91.1	8.9 (3-11)
Klingaman et al,37 2018	United States	Tertiary	Prospective	505	GA ≥35 wk	505	2 (0.4)	CDC informed	NA	9 (17.8)	1.4	22.2 (5-102)

Abbreviations: AAP, American Academy of Pediatrics; AB, antibiotics; CDC, Centers for Disease Control and Prevention; CFN, Committee on the Fetus and Newborn; EOS, early-onset sepsis; GA, gestational age; NA, not applicable; NR, not reported.

^aBirths = number of births in total study period in the eligible GA range; included = inclusion criteria used to select study population; chorioamnionitis = newborns with a mother who received a diagnosis of chorioamnionitis; reduction in AB = (hypothetical) reduction in empirical AB for EOS achieved by using the EOS calculator.

^bReduction range reported (precluding calculation of meaningful CI), as depending on outcome of newborns in observe-and-evaluate category.

^cStudies limited to AB-treated infants; reported results represent estimations of maximum potential reduction of empirical AB by EOS calculator use.

^dSampling of study excluded 41 infants who were symptomatic at birth and 38 infants developing symptoms after initial examination, resulting in an estimated reduction that does not reflect a potential implementation scenario.