Table 1 Comparison of baseline variables for those retained and those lost-to-follow-up

Total

27,713 (79.9)

6,958 (20.1)

Parity

 Primi/Multiparous

15,795 (57.0)

3,717 (53.4)

<0.001

 Nulliparous

11,918 (43.0)

3,241 (46.6)

Educational level

 None or primary

1,299 (4.7)

393 (5.7)

<0.001

 Secondary or tertiary

17,285 (62.4)

4,085 (58.7)

 Missing

9,129 (32.9)

2,480 (35.6)

Race

 Other

532 (1.9)

140 (2.0)

<0.001

 Coloured

18,046 (65.1)

4,126 (59.3)

 Black

9,135 (33.0)

2,692 (38.7)

Smoking

 No

13,580 (49.0)

3,323 (47.8)

<0.001

 Yes

6,704 (24.2)

1,441 (20.7)

 Missing

7,429 (26.8)

2,194 (31.5)

First ANC visit facility

 Primary care facility 1

1,528 (5.5)

191 (2.8)

<0.001

 Primary care facility 2

6,673 (24.1)

3,536 (50.8)

 Primary care facility 3

12,659 (45.7)

1,675 (24.1)

 Primary care facility 4

6,853 (24.7)

1,556 (22.4)

First ANC visit year

 2006

2,788 (10.1)

1,699 (24.4)

<0.001

 2007

10,094 (36.4)

2,663 (38.3)

 2008

11,946 (43.1)

1,913 (27.5)

 2009

2,885 (10.4)

683 (9.8)

Gestational age at first ANC visit (3 Categories)

 1 ^st trimester

2,026 (7.3)

778 (11.2)

<0.001

 2 ^nd trimester

16,641 (60.1)

4,278 (61.5)

 3 ^rd trimester

9,046 (32.6)

1,902 (27.3)

Mean (SD)

Mean (SD)

Gestational age at first ANC visit (Continuous)

23.0 (7.2)

21.8 (7.3)

<0.001

Maternal age

25.4 (6.0)

25.6 (6.2)

0.07