Table 4:

Neonatal outcomes, by study period

Variable	Control vaccine		Influenza vaccine		OR (95% CI)*	p value	Adjusted OR (95% CI)*†	p value‡
	No.	% (95% CI)*	No.	% (95% CI)*
No influenza virus circulating (Sept. 2004–Jan. 2005)		n = 108		n = 103
Birth weight, g, mean	–	3053 (2967 to 3139)	–	3083 (3000 to 3176)	30 (−98 to 157)**	0.9††	–
Small for gestational age§	37	34.3 (25.1 to 42.9)	30	29.1 (20.2 to 37.8)	0.79 (0.44 to 1.41)	0.4	–
Born before 37 weeks’ gestation	10	9.3 (3.8 to 14.8)	8	7.8 (2.6 to 13.0)	0.83 (0.31 to 2.18)	0.7	–
Weight < 2500 g	8	7.4 (2.5 to 12.3)	6	5.8 (1.3 to 10.3)	0.77 (0.26 to 2.31)	0.6	–
Apgar score at 1 min, mean	–	7.7 (7.3 to 8.1)	–	7.6 (7.3 to 8.1)	–	0.7	–
Female	46¶	42.9 (32.7 to 51.3)	43	41.8 (31.5 to 50.5)	0.97 (0.56 to 1.67)	0.9	–
Influenza virus circulating (Feb. 2005–Oct. 2005)		n = 58		n = 58
Birth weight, g, mean	–	2978 (2849 to 3107)	–	3178 (3058 to 3298)	200 (191 to 209)**	0.02††	193 (9 to 378)‡‡	0.01
Small for gestational age§	26	44.8 (31.2 to 56.8)	15	25.9 (13.9 to 36.1)	0.43 (0.20 to 0.94)	0.03	0.44 (0.19 to 0.99)	0.05
Born before 37 weeks’ gestation	4	6.9 (0.4 to 13.4)	2	3.5 (0 to 8.2)	0.48 (0.08 to 2.74)	0.4	0.32 (0.05 to 2.29)§§	0.3
Weight < 2500 g	5	8.6 (1.4 to 15.8)	1	1.7 (0 to 5.0)	0.19 (0.02 to 1.64)	0.09	0.17 (0.02 to 1.63)	0.1
Apgar score at 1 min, mean	–	7.3 (6.6 to 8.0)	–	7.7 (7.3 to 8.2)	–	0.3	–
Female	26	44.8 (31.2 to 56.8)	27	46.6 (33.2 to 58.9)	1.07 (0.52 to 2.23)	0.9	1.12 (0.53 to 2.39)	0.8

Note: CI = confidence interval, OR = odds ratio.

^*Unless stated otherwise.

^†Adjusted for gestational age at immunization, and interval from immunization to delivery.

^‡χ² test.

^§Infants who were below the tenth percentile of weight for gestational age.

^¶Calculated from a total of 107 infants due to missing sex data for one infant.

^**Mean difference (95% CI).

^††Mann–Whitney U test.

^‡‡Adjusted mean difference.

^§§Adjusted only for interval from immunization to delivery.