Table 1.

Characteristics of the cohort (n = 109).

	Australia	Japan	Norway	South Africa	USA
	(n = 29)	(n = 12)	(n = 40)	(n = 10)	(n = 18)
Maternal atopy	21 (72%)	6 (50%)	9 (23%)	0 (0%)	11 (61%)
Maternal race
Caucasian	28 (100%)	0 (0%)	34 (85%)	2 (20%)	11 (61%)
Asian	0 (0%)	12 (100%)	0 (0%)	0 (0%)	0 (0%)
Black	0 (0%)	0 (0%)	0 (0%)	2 (20%)	7 (39%)
Mixed race	0 (0%)	0 (0%)	0 (0%)	6 (60%)	0 (0%)
Other race	0 (0%)	0 (0%)	6 (15%)	0 (0%)	0 (0%)
Maternal age (years)	33.8 ± 5.2	24.6 ± 5.5	29.4 ± 5.2	29.8 ± 4.8	29.6 ± 4.4
Maternal parity	1.3 ± 0.5	1.7 ± 1.0	1.5 ± 0.5	2.0 ± 0.9	2.2 ± 1.2
Maternal pre-pregnancy BMI		20.7 ± 2.5	28.1 ± 6.6	25.0 ± 2.9	27.2 ± 5.6
Maternal antibiotics	4 (14%)*	0 (0%)	5 (13%)∧	0 (0%)	0 (0%)
Cesarean delivery	1 (4%)	0 (0%)	0 (0%)	0 (0%)	0 (0%)
Male infant	13 (46%)	6 (50%)	25 (63%)	5 (50%)	6 (33%)

Values are reported as n (percent) or mean ± SD.

Blank cells represent missing data.

^*One case of intrapartum Cefazolin for cesarean delivery, two cases of intrapartum penicillin for Group B Streptococcus, one case of intrapartum antibiotics with no class or reason recorded.

^∧All exposures were in early pregnancy. Class of antibiotic was not recorded.