Table 1.
Estimates of prevalence (P), intracluster correlation coefficients (ICC), their respective 95% CI, design effect (Deff), and mean cluster size (n a ) for categorical maternal characteristics
| Variables | P (%) | ICC | 95% CI for ICC | Deff | n a |
|---|---|---|---|---|---|
| Skin color (white) |
43.1 |
0.145 |
0.058-0.233 |
42.2 |
265 |
| Marital status (with a partner) |
77.7 |
0.008 |
<0.001-0.016 |
3.2 |
265 |
| Schooling (>8 years) |
60.5 |
0.030 |
0.008-0.053 |
10.6 |
261 |
| Children under 5 years (≥1) |
27.1 |
0.005 |
<0.001-0.011 |
2.4 |
265 |
| Time since last delivery (until 12 months) |
8.4 |
0.011 |
<0.001-0.022 |
2.8 |
155 |
| Previous cerclage |
1.1 |
0.001 |
<0.001-0.004 |
1.2 |
264 |
| Previous preterm birth |
17.3 |
0.007 |
<0.001-0.013 |
3.2 |
264 |
| Previous preterm birth of multiples |
1.0 |
<0.001 |
<0.001-0.003 |
1.2 |
264 |
| Previous preterm labor |
7.4 |
0.011 |
0.001-0.021 |
4.3 |
264 |
| Previous prelabor PROM |
7.2 |
0.002 |
<0.001-0.006 |
1.8 |
264 |
| Previous indicated preterm birth |
7.7 |
0.004 |
<0.001-0.009 |
2.0 |
263 |
| Previous newborn weight < 2500 g |
14.8 |
0.010 |
<0.001-0.019 |
4.1 |
262 |
|
Previous chronic diseases: | |||||
| ● Chronic hypertension |
8.2 |
0.004 |
<0.001-0.009 |
2.4 |
265 |
| ● Diabetes mellitus |
2.1 |
0.010 |
0.001-0.019 |
3.6 |
265 |
| ● Thyroid disease |
1.8 |
0.012 |
0.002-0.023 |
4.4 |
265 |
| ● Cardiac disease |
1.3 |
0.002 |
<0.001-0.005 |
1.4 |
265 |
| ● Lung disease |
2.9 |
0.006 |
<0.001-0.012 |
2.8 |
265 |
| ● Renal disease |
1.8 |
0.013 |
0.002-0.024 |
4.7 |
265 |
| ● Digestive disease |
1.3 |
0.009 |
0.001-0.018 |
3.3 |
265 |
| ● Hematological disease |
1.4 |
0.012 |
0.002-0.023 |
4.7 |
265 |
| ● Neurological disease |
1.2 |
0.008 |
<0.001-0.016 |
3.7 |
265 |
| ● Psychiatric disease |
1.4 |
0.022 |
0.005-0.038 |
7.0 |
265 |
| ● HIV |
1.3 |
0.006 |
<0.001-0.012 |
2.6 |
265 |
| ● Other | 6.5 | 0.033 | 0.009-0.057 | 11.8 | 265 |