Table 1 Baseline sociodemographic characteristics

Number of mothers

300 (51)

285 (49)

585 (100)

Cohort

 Main

1 (0)

141 (49)

142 (24)

<0.001

 Intensive

299 (100)

144 (51)

443 (76)

Race

 Black

298 (99)

3 (1)

301 (51)

<0.001

 Mixed race

2 (1)

282 (99)

284 (49)

Median age at enrolment (IQR)

27.4 (22.6–32.1)

25.5 (22.1–30.1)

26.6 (22.4–31.3)

0.006

Marital status

 Married/cohabiting

104 (35)

117 (41)

221 (38)

0.111

Gravidity

 Primigravida

87 (29)

112 (39)

199 (34)

0.009

Highest level of education

 Some secondary

197 (66)

175 (61)

372 (64)

0.284

 Completed secondary

103 (34)

110 (39)

213 (36)

Current employment status

 Employed

58 (19)

80 (28)

138 (24)

0.013

Average household income

  < R1000/month

153 (51)

107 (38)

260 (44)

 R1000-R5000/month

120 (40)

133 (47)

253 (43)

0.002

  > R5000/month

27 (9)

45 (16)

72 (12)

Composite SES quartile

 Lowest SES

94 (31)

47 (16)

141 (24)

 Low-moderate SES

81 (27)

51 (18)

132 (23)

<0.001

 Moderate-high SES

63 (21)

89 (31)

152 (26)

 High SES

62 (21)

98 (34)

160 (27)

Prior participation in research

71 (24)

34 (12)

105 (18)

<0.001