Table 3  Incidence RR of each PCB-153 quartile of prenatal exposure compared to the first quartile.
Unadjusted (n = 199)  Adjusted (n = 177)a
Incidence RR (95% CI)b   Incidence RR (95% CI)b
Infection type  2nd quartile (n = 50)  3rd quartile (n = 50)  4th quartile (n = 50)  p-Value for trendc  2nd quartile (n = 40)  3rd quartile (n = 46)  4th quartile (n = 45)  p-Value for trendc
6-Month follow-up
 URTIs  1.08 (0.76–1.55)  0.98 (0.68–1.41)  1.19 (0.84–1.68)  0.69  1.08 (0.69–1.67)  1.08 (0.71–1.65)  1.32 (0.87–2.00)  0.22
 Otitis media  1.33 (0.85–2.07)  1.15 (0.73–1.82)  1.30 (0.83–2.02)  0.17  1.11 (0.65–1.89)  0.99 (0.59–1.66)  1.39 (0.82–2.35)  0.17
 GI infections  1.63 (0.80–3.34)  1.31 (0.62–2.76)  1.55 (0.75–3.20)  0.33  1.89 (0.78–4.56)  1.52 (0.65–3.54)  1.54 (0.66–3.60)  0.38
 LRTIs  1.12 (0.71–1.76)  1.54 (1.01–2.35)*  1.01 (0.63–1.61)  0.61  1.16 (0.65–2.09)  1.68 (1.00–2.81)*  1.18 (0.68–2.04)  0.38
 All infectionsd  1.19 (0.95–1.50)  1.18 (0.94–1.48)  1.19 (0.95–1.50)  0.14  1.17 (0.88–1.55)  1.19 (0.92–1.54)  1.27 (0.98–1.66)  0.04*
12-Month follow-up
 URTIs  0.93 (0.72–1.20)  0.87 (0.67–1.13)  1.12 (0.88–1.43)  0.81  0.99 (0.71–1.36)  0.96 (0.71–1.29)  1.23 (0.92–1.65)  0.29
 Otitis media  1.05 (0.83–1.32)  0.97 (0.76–1.22)  0.94 (0.75–1.20)  0.89  1.02 (0.77–1.35)  0.89 (0.68–1.17)  0.97 (0.73–1.28)  0.89
 GI infections  1.27 (0.86–1.88)  1.22 (0.82–1.82)  1.05 (0.69–1.58)  0.81  1.53 (0.94–2.49)  1.59 (1.01–2.49)*  1.26 (0.78–2.04)  0.29
 LRTIs  0.88 (0.65–1.19)  1.08 (0.81–1.45)  0.96 (0.71–1.29)  0.48  0.86 (0.57–1.28)  1.10 (0.78–1.55)  1.03 (0.72–1.48)  0.36
 All infectionsd  1.00 (0.87–1.15)  0.99 (0.86–1.14)  1.01 (0.88–1.16)  0.67  1.02 (0.86–1.21)  1.01 (0.86–1.19)  1.08 (0.92–1.28)  0.24
CI, confidence interval.
a  Model included mother’s age, season of birth, year of birth, breast-feeding duration, sex, socioeconomic status of the caregiver, tobacco use during pregnancy, village of residence, and number of children living with the participant.
b  Incidence RR when the given quartile was compared to the first quartile of exposure (Poisson regression).
c  p-Values for trends were calculated by Poisson regression in which the contaminant concentration (lipid-based) was entered as a continuous variable (log-transformed).
d  Only infections with a mean incidence > 1.0 episode/year/infant were included; see details in “Materials and Methods”).
*  p < 0.05.