Table 2.

Change in gestational age, birth weight and ponderal index according to HCB levels in human milk among 300 newborns.

			Crude model		Adjusted model
	N	Mean	β	(95 % CI)	β	(95 % CI)
Gestational age (days)
HCB level μg/kg lipid:
4 to 11.99	172	280	ref		ref
12 to 19.99	110	282	2.2	(−0.6 to 5.1)	3.3	(−0.05 to 6.7)
>20	18	278	−2.0	(−7.8 to 3.9)	0.5	(−6.5 to 7.4)
Per 8 units increase in HCB:			−2.3	(−4.8 to 0.3)	−2.8	(−6.1 to 0.51)
Birth weight (g)
HCB level μg/kg lipid:
4 to 11.99	172	3695	ref		ref
12 to 19.99	110	3727	32	(−100 to 164)	−50	(−181 to 80)
>20	18	3497	−198	(−466 to 70)	−253	(−522 to 15)
Per 8 units increase in HCB:			−109	(−224 to 6)	−90	(−275 to 8)
Ponderal Index (g/cm3)
HCB level μg/kg lipid:
4 to 11.99	167	2.84	ref		ref
12 to 19.99	109	2.81	−0.04	(−0.11 to 0.02)	−0.08	(−0.20 to −0.004)
>20	18	2.74	−0.08	(−0.21 to 0.05)	−0.14	(−0.29 to 0.01)
Per 8 units increase in HCB:			−0.05	(−0.10 to 0.01)	−0.08	(−0.15 to −0.004)

The model with gestational age as an outcome was adjusted for parity, maternal smoking, age, height, pre-pregnancy BMI, education, county of residence and the sum of 6 PCB congeners (CB-28, −52, −101, −138, −153, −180). All other models were in addition adjusted for gestational age (plus gestational age squared) and infant’s sex. Only 299 subjects were included in the adjusted analysis due to one subject with missing value for smoking status, while missing values were imputed for 11 subjects (4%).