TABLE 2.

Correlations between hemoglobin concentrations and iron status indicators in a cohort of pregnant adolescents and women carrying multiple fetuses¹

	SF	sTfR	TBI	EPO
Pregnancy (26.0 ± 3.4 wk of gestation)
Hemoglobin
Nonanemic
r	0.07	0.16	−0.02	−0.23
P	0.43	0.052	0.80	0.008
n	144	144	144	133
Anemic
r	0.25	−0.46	0.41	−0.57
P	0.04	0.0001	0.0009	<0.0001
n	64	64	64	58
SF
Nonanemic
r	—	−0.19	ND	−0.11
P	—	0.01	ND	0.16
n	—	173	ND	160
Anemic
r	—	−0.39	ND	−0.48
P	—	0.0003	ND	<0.0001
n	—	79	ND	72
sTfR
Nonanemic
r	—	—	ND	0.25
P	—	—	ND	0.002
n	—	—	ND	160
Anemic
r	—	—	ND	0.53
P	—	—	ND	<0.0001
n	—	—	ND	72
TBI
Nonanemic
r	—	—	—	−0.21
P	—	—	—	0.008
n	—	—	—	160
Anemic
r	—	—	—	−0.60
P	—	—	—	<0.0001
n	—	—	—	72
Delivery (39.2 ± 2.7 wk of gestation)
Hemoglobin
Nonanemic
r	0.24	−0.15	0.26	−0.27
P	0.0006	0.04	0.0002	0.0002
n	200	202	200	186
Anemic
r	0.21	−0.26	0.27	−0.43
P	0.07	0.02	0.02	0.0002
n	75	76	75	68
SF
Nonanemic
r	—	−0.16	ND	−0.25
P	—	0.02	ND	0.0004
n	—	210	ND	194
Anemic
r	—	−0.46	ND	−0.42
P	—	<0.0001	ND	0.0002
n	—	85	ND	77
sTfR
Nonanemic
r	—	—	ND	0.17
P	—	—	ND	0.02
n	—	—	ND	195
Anemic
r	—	—	ND	0.52
P	—	—	ND	<0.0001
n	—	—	ND	77
TBI
Nonanemic
r	—	—	—	−0.28
P	—	—	—	<0.0001
n	—	—	—	194
Anemic
r	—	—	—	−0.54
P	—	—	—	<0.0001
n	—	—	—	77

¹Correlations between iron status indicators are shown during pregnancy and at delivery for those who remained nonanemic or for those who developed anemia across gestation. EPO, erythropoietin; ND, not determined (because TBI is calculated by using SF and transferrin receptor); SF, serum ferritin; sTfR, soluble transferrin receptor; TBI, total body iron.