Table 1.

Epidemiological characteristics of cases and controls.

	Case	Control	P < 0.05
Sex (% male)	54	46
Number of individuals per room of the house	3.15	3.06
Average parental income (US$ per month)	222	229
Average birth weight (g)	3,390	3,341
Average birth height (cm)	49.6	49.1
Maternal education (%)
Illiterate	2%	2%
Primary incomplete	17%	13%
Primary complete	23%	22%
Secondary incomplete	15%	16%
Secondary complete	32%	44%	*
University incomplete	10%	3%	*
University complete	1%	0%
Respiratory tract infections (episodes per person)	0.02	0.04
Antibiotics (numbers of times used per person)	0.06	0.07
Malnutrition (% reported)	2%	2%
Anemia (% reported)	1%	3%

^*P < 0.05. Maternal education refers to the last formal instruction the mother had at the time of the cohort inclusion.