Table 2.

Characteristic of pregnant Peruvian women residing at low (150 m) and at high altitudes (>3,000 m), 2003–2006

Characteristic	Altitude
	Low (n = 8,409)		High (n = 27,040)
	n	% CI 95%	n	% CI 95%
Hemoglobin level*
<9 g/dl	213	2.5 (2.20–2.89)	183	0.6 (0.58–0.78)
9–10.9 g/dl	2481	29.5 (28.5–30.4)	1083	4.0 (3.77–4.24)
11.0–12.9 g/dl	5081	60.4 (59.3–61.4)	8049	29.7 (29.2–30.3)
≥13.0 g/dl	634	7.5 (6.98–8.12)	17725	65.5 (64.9–66.1)
Maternal age
<20yr	1304	15.5 (14.7–16.2)	4935	18.2 (17.7–18.8)
20–34 yr	6051	71.9 (70.9–72.9)	18982	70.1 (69.6–70.7)
>34 yr	1054	12.5 (11.8–13.2)	3123	11.5 (11.2–11.9)
Education*
None	65	0.7 (0.59–0.98)	837	3.1 (2.89–3.30)
Primary	388	4.6 (4.17–5.08)	5352	19.7 (19.3–20.2)
Secondary	5730	68.1 (67.1–69.1)	12656	46.8 (46.2–47.4)
Superior	2226	26.4 (25.5–27.4)	8195	30.3 (29.7–30.8)
BMI, kg/m2
<19.9*	1008	11.9 (11.3–12.7)	2575	9.5 (9.17–9.87)
19.9–25.0*	5129	60.9 (59.9–62.0)	17412	64.3 (63.8–64.9)
>25	2272	27.0 (26.0–27.9)	7053	26.1 (25.5–26.6)
Parity
None*	3827	45.5 (44.4–46.5)	11486	42.4 (41.8–43.1)
1–3	4166	49.5 (48.4–50.6)	12855	47.5 (46.9–48.1)
≥4*	416	4.9 (4.49–5.43)	2699	9.9 (9.62–10.3)
Prenatal care*
None	3007	35.7 (34.7–36.7)	3727	13.7 (13.3–14.1)
1–5	1827	21.7 (20.8–22.6)	7076	26.1 (25.6–26.6)
>5	3575	42.5 (41.4–43.5)	16237	60.0 (59.4–60.6)
Previous perinatal death/preterm*	228	2.7 (2.37–3.08)	1564	5.8 (5.50–6.06)
Gestational hypertension	275	3.3 (2.90–3.67)	954	3.5 (3.31–3.75)
Abruptio Placentae	30	0.3 (0.24–0.50)	92	0.3 (0.27–0.41)
Migration*	8	0.1 (0.04–0.18)	981	3.6 (3.40–3.85)

Confidence intervals (CIs) appear in parentheses.

^*χ²-test of differences between high and low altitude. BMI, body mass index.