Association between Maternal Plasma Ferritin Level and Infants’ Size at Birth: A Prospective Cohort Study in Rural Bangladesh

Figures & data

Figure 1. Flowchart of participating women

Table 1. Background characteristics of the mothers and their children (n = 573)

Characteristics	Number	Mean± SD or percentage	Median	5th–95th percentile
Mothers
Age (years)	573	26 ± 6.1	26	18.0–37.0
Height (cm) at GW8 (kg)	573	150 ± 5.5	150	142 − 160
Weight at GW8 (kg)	573	51 ± 70	44.2	34.9–59.5
BMI at GW8 (kg/m^2)	573	20.0 ± 2.7	19.6	16.2–25.4
Pregnancy weight gain (kg)^a	569	5.4 ± 2.5	5.3	1.6–9.5
Education (years)
No education	182	31.8%
1–5	124	21.6%
6 or more	267	46.6%
Socioeconomic status (SES)
Poorest	179	31.2%
Middle class	198	34.6%
Wealthiest	196	34.2%
Parity
Nulliparous	182	31.8%	1.5 ± 1.4	0.433
1–2	275	48.0%
3 or more	116	20.2%
P-ferritin (µg/L) at GW14	573	42.5 ± 29.1	35.6	11.1–97.6
P-ferritin (µg/L) at GW30	573	20.0 ± 14.4	16.7	4.6–49.4
Hb (g/L) at GW14	573	117 ± 12.2	116	100–139
Hb (g/L) at GW30	573	115 ± 11.8	115	97–135
Newborns
Sex
Boy	305	53.2%
Girl	268	46.8%
Gestational age at birth (weeks)	573	38.7 ± 2.2	39	35–42
Weight (g)	573	2,682 ± 400	2,670	2042–3400
Length (cm)	573	47.9 ± 2.2	48	44–51.8

SD: standard deviation; GW: gestational week; Hb: hemoglobin.

^aWeight gain between GW8 and GW30.

Table 2. Multivariable linear regression analysis of infants’ size at birth (birth weight and length) in relation to plasma ferritin concentration (µg/L) categorized in tertiles at 14 weeks and 30 weeks of pregnancy (n = 573)

	Birth weight		Birth length
	Β coefficient	95% CI	Β coefficient	95% CI
Plasma ferritin at GW14
Crude model
<25	Reference		Reference
25–45	23	−58, 105	0.02	−0.43, 0.47
>45	− 43	−124, 58	−0.18	−0.62, 0.26
Adjusted model ^a
<25	Reference		Reference
25–45	3.8	−75, 83	0.09	−0.53, 0.35
>45	− 70	−146, 7.6	−0.31	−0.74, 0.126
Plasma ferritin at GW30
Crude model
<12	Reference		Reference
12–21	−18	−99, 63	0.15	−0.29, 0.60
>21	− 74	−156, 8.54	−0.21	−0.66, 0.23
Adjusted model ^a
<12	Reference		Reference
12–21	−31	−109, 48	0.07	−0.37, 0.51
>21	−93	−172, −14*	−0.33	−0.77, 0.11

^aAdjusted for maternal BMI, education, parity, and newborn sex.

*Statistically significant.

Table 3. Multivariable logistic regression analysis of the association between plasma ferritin concentration (µg/L) categorized in tertiles at 14 weeks and 30 weeks of pregnancy (n = 573) and low birth weight (LBW) infant and preterm birth

	Low birth weight		Preterm birth
	OR	95% CI	OR	95% CI
Plasma ferritin at GW14
Crude model
<25	1.00		1.00
25–45	0.96	0.62, 1.50	1.32	0.65, 2.72
>45	1.27	0.82, 1.94	1.24	0.61, 2.54
Adjusted model^a
<25	1.00		1.00
25–45	1.10	0.68, 1.76	1.33	0.63, 2.79
>45	1.50	0.95, 2.36	1.33	0.64, 2.77
Plasma ferritin at GW30
Crude model
<12	1.00		1.00
12–21	1.34	0.85, 2.11	1.00	0.47, 2.15
>21	1.87	1.20, 2.93*	1.71	0.85, 3.46
Adjusted model^a
<12	1.00		1.00
12–21	1.49	0.92, 2.42	0.87	0.40, 1.92
>21	2.27	1.40, 3.67*	1.65	0.80, 3.38

^aAdjusted for maternal BMI, education, parity, and newborn sex.

*Statistically significant.

Availability of data

The datasets during and/or analyzed during the current study available from the corresponding author on reasonable request.