TABLE 1

Frequencies for Each of the Responses and Missing Data for Categorical Predictor, Control, and Outcome Variables Before Data Imputation (N = 5107)

VariableN (%)
Sex of child
 Male2608 (51.1)
 Female2499 (48.9)
 Missing0 (0.0)
Wave 1 child still breastfeeding
 Yes2007 (39.3)
 No3096 (60.6)
 Missing4 (0.1)
Child was breastfed at any time
 Yes4685 (91.7)
 No418 (8.2)
 Missing4 (0.1)
Mother’s trimester 1 d per wk drinking alcohol
 0 or occasional3934 (77)
 1141 (2.8)
 285 (1.7)
 332 (0.6)
 417 (0.3)
 512 (0.2)
 65 (0.1)
 74 (0.1)
 Missing877 (17.2)
Mother’s trimester 2 d per wk drinking alcohol
 0 or occasional3823 (74.9)
 1206 (4.0)
 2118 (2.3)
 348 (0.9)
 419 (0.4)
 59 (0.2)
 65 (0.1)
 73 (0.1)
 Missing876 (17.2)
Mother’s trimester 3 d per wk drinking alcohol
 0 or occasional3802 (74.4)
 1190 (3.7)
 2133 (2.6)
 354 (1.1)
 424 (0.5)
 514 (0.3)
 66 (0.1)
 75 (0.1)
 Missing879 (17.2)
Pregnancy: average No. drinks on drinking d
 0 or none2597 (50.9)
 1 or 21560 (30.5)
 3 or 456 (1.1)
 5 or 67 (0.1)
 7–103 (0.1)
 11 or more5 (0.1)
 Missing879 (17.2)
Mother’s level of education
 Never attended or still attending school4 (0.1)
 ≤Year 883 (1.6)
 Year 9 or Eq161 (3.2)
 Year 10 or Eq820 (16.1)
 Year 11 or Eq539 (10.6)
 Year 12 or Eq1813 (35.5)
 Bachelor degree998 (19.5)
 Graduate diploma or certificate319 (6.2)
 Postgraduate degree361 (7.1)
 Missing9 (0.2)
Combined family income (Australian dollars)
 ≥$2400 per wk or ≥$124 800 per y384 (7.5)
 $2200–$2399 per wk or $114 400–$124 799 per y106 (2.1)
 $2000–$2199 per wk or $104 000–$114 399 per y158 (3.1)
 $1500–$1999 per wk or $78 000–$103 999 per y674 (13.2)
 $1000–$1499 per wk or $52 000–$77 999 per y1295 (25.4)
 $800–$999 per wk or $41 600–$51 999 per y685 (13.4)
 $700–$799 per wk or $36 400–$41 599 per y367 (7.2)
 $600–$699 per wk or $31 200–$36 399 per y287 (5.6)
 $500–$599 per wk or $26 000–$31 199 per y266 (5.2)
 $400–$499 per wk or $20 800–$25 999 per y273 (5.3)
 $300–$399 per wk or $15 600–$20 799 per y231 (4.5)
 $200–$299 per wk or $10 400–$15 599 per y78 (1.5)
 $100–$199 per wk or $5200–$10 399 per y17 (0.3)
 $50–$99 per wk or $2600–$5199 per y7 (0.1)
 $1–$49 per wk or $1–$2599 per y1 (<0.1)
 Nil income2 (<0.1)
 Negative income4 (0.1)
 Missing272 (5.3)
Mother’s frequency of drinking alcohol (modified AUDIT-C question 1)
 Never387 (7.6)
 Not in the last y414 (8.1)
 Monthly or less1234 (24.2)
 2–3 times a mo582 (11.4)
 Once a wk590 (11.6)
 2–3 times a wk604 (11.8)
 4–6 times a wk303 (5.9)
 Every d91 (1.8)
 Missing902 (17.7)
Mother’s average No. drinks when drinking (modified AUDIT-C question 2)
 0387 (7.6)
 1 or 22484 (48.6)
 3 or 4611 (12.0)
 5 or 6184 (3.6)
 7–1064 (1.3)
 ≥1117 (0.3)
 Missing1360 (26.6)
Mother’s frequency of drinking ≥5 drinks in 1 sitting (modified AUDIT-C question 3)
 Not in the last y2879 (56.4)
 Monthly or less1022 (20.0)
 2 or 3 times a mo148 (2.9)
 Once a wk95 (1.9)
 2–3 times a wk46 (0.9)
 4–6 times a wk7 (0.1)
 Every d1 (0.1)
 Missing909 (17.8)
Head injury wave 3a
 Yes7 (0.1)
 No4379 (85.7)
 Missing721 (14.1)
Head injury wave 4a
 Yes19 (0.4)
 No4223 (82.7)
 Missing865 (16.9)
Head injury wave 5a
 Yes24 (0.5)
 No4024 (78.8)
 Missing1059 (20.7)
Head injury wave 6a
 Yes28 (0.5)
 No3670 (71.9)
 Missing1409 (27.6)
Learning difficulty wave 3
 Yes84 (1.6)
 No4302 (84.2)
 Missing721 (14.1)
Learning difficulty wave 4
 Yes25 (0.5)
 No4217 (82.6)
 Missing865 (16.9)
Learning difficulty wave 5
 Yes92 (1.8)
 No3955 (77.4)
 Missing1060 (20.8)
Learning difficulty wave 6
 Yes107 (2.1)
 No3670 (71.9)
 Missing1409 (27.6)
  • a Head injuries noted at earlier waves were automatically recorded at all later waves.