Table 2 Pregnancy characteristics of women in the study (i), crude and adjusted odds ratio (OR) and 95% confidence intervals for odds ratios (95%CI) comparing prison pregnancies with controls

1st antenatal visit >20 weeks gestation

Prison pregnancy (ii)

130

47.4

1.63

1.63 (1.24-2.14)*

6.82

4.05 (3.12-5.27)*

Prison controls (iii)

393

33.9

1.00

1.00

Community (iv)

3928

10.1

1.00

1.00

Not booked at admission

Prison pregnancy (ii)

55

19.0

1.31

1.17 (0.83-1.64)

8.92

3.24 (2.29-4.57)*

Prison controls (iii)

180

14.9

1.00

1.00

Community (iv)

959

2.6

1.00

1.00

Maternal diabetes mellitus

Prison pregnancy (ii)

1

0.3

0.45

0.43 (0.05-3.44)

0.55

0.41 (0.06-3.10)

Prison controls (iii)

9

0.7

1.00

Community (iv)

237

0.6

1.00

1.00

Gestational diabetes

Prison pregnancy (ii)

5

1.7

0.58

0.63 (0.24-1.62)

0.35

0.56 (0.23-1.39)

Prison controls (iii)

35

2.8

1.00

1.00

Community (iv)

1799

4.6

1.00

1.00

Maternal hypertension

Prison pregnancy (ii)

2

0.7

2.06

2.12 (0.39-11.65)

0.62

0.78 (0.19-3.31)

Prison controls (iii)

4

0.3

1.00

1.00

Community (iv)

419

1.1

1.00

1.00

Gestational hypertension

Prison pregnancy (ii)

8

2.8

0.77

0.80 (0.37-1.72)

0.41

0.49 (0.24-1.01)

Prison controls (iii)

42

3.5

1.00

1.00

Community (iv)

2448

6.5

1.00

1.00