Table 1.

Socio-demographic and reproductive characteristics and infant outcomes in the study sample, Lima, Peru, 2009-2010

	Spontaneous preterm birth
	Term controls (N = 480)		Cases (N = 479)
Characteristics	n	%	n	%	P-value
Maternal age at delivery (years)	28.3 ± 6.5		28.2 ± 6.6		0.74
<20	42	8.8	49	10.2	0.49
20-29	235	49.0	228	47.6
30-34	94	19.6	107	22.3
≥35	109	22.7	95	19.8
Primiparity	199	41.5	205	42.8	0.68
≤High school education	335	69.8	319	66.6	0.29
Employed during pregnancy	195	40.6	177	37.0	0.24
Planned pregnancy	209	43.5	152	31.7	<0.001
No Prenatal care	19	4.0	75	15.7	<0.001
No Prenatal vitamin	68	14.2	119	24.8	<0.001
Smoked during pregnancy	1	0.2	4	0.8	0.22
Alcohol use during pregnancy	157	32.7	150	31.3	0.64
Illicit drug use during pregnancy	0	0.0	3	0.6	---
Pre-pregnancy weight (kg)	58.0 ± 9.8		56.7 ± 10.0		0.04
Infant birth weight (grams)	3393 ± 462		1999 ± 663		<0.001
Low birth weight infant (<2500grams)	14	2.9	381	76.5	<0.001

Continuous measures: Mean ± SD (SD = standard deviation).