Table 1 General characteristics of the study participants (N = 1406)

Age (years)

 8

418(29.7)

 9

372(26.5)

 10

363(25.8)

 11

253(18.0)

Sex

 Male

672(47.8)

 Female

734(52.2)

Socio-economic status

 High

521(37.1)

 Middle

439(31.2)

 Low

446(31.7)

Type of family

 Monogamy

1341(95.4)

 Polygamy

65(4.6)

Form of parenthood

 Both parents

1186(84.4)

 One of the parents

46(3.2)

 Relative/guardian

174(12.4)

Birth rank

 Only child

38(2.7)

 First child

326(23.2)

 Last child

313(22.3)

 Others

729(51.8)

Number of siblings

 0

38(2.7)

 1–2

245(17.4)

 3–4

570(40.5)

 >4

553(39.4)