Background
Methods
No. of records total 1990-2005: 451742 | ||||
---|---|---|---|---|
Minimum no. in a year (1997): 27484 | ||||
Maximum no. in a year (2005): 29456 |
Frequency
|
% of total
|
% Preterm after Exclusions
|
Unadjusted Odds Ratio
|
Ethnicity
| ||||
Asian | 5889 | 1.3 | 8.66 | 0.97 |
Other | 254 | 0.06 | 12.7 | 1.49 |
White Hispanic | 219893 | 48.68 | 9.26 | 1.049 |
Native American | 63115 | 13.97 | 7.77 | 0.869 |
Black | 8378 | 1.85 | 12.7 | 1.49 |
White Non-Hispanic | 154213 | 34.14 | 8.92 | Reference |
Missing | 26673 | 5.9 | 20 | 6 |
Inadequate | 107576 | 23.81 | 8.66 | 2.28 |
Intermediate | 80289 | 17.77 | 3.63 | 0.90 |
Adequate | 139993 | 30.99 | 4 | Reference |
Intensive | 97211 | 21.52 | 18.01 | 5.27 |
Maternal Age
| ||||
< 15 | 1446 | 0.32 | 14.43 | 1.90 |
15-19 | 75920 | 16.81 | 9.76 | 1.22 |
20-24 | 135445 | 29.98 | 8.63 | 1.06 |
25-29 | 114764 | 25.4 | 8.16 | Reference |
30-34 | 79154 | 17.52 | 8.91 | 1.10 |
35-39 | 36438 | 8.07 | 10.46 | 1.31 |
> = 40 | 8307 | 1.84 | 12.4 | 1.59 |
Missing | 268 | 0.06 | ||
Maternal Education Level (# of years)
| ||||
< 9 | 27216 | 6.02 | 8.75 | 0.96 |
9-12 | 259107 | 57.36 | 9.11 | Reference |
13-16 | 120997 | 26.78 | 8.33 | 0.91 |
> 16 | 30040 | 6.65 | 8.26 | 0.90 |
Missing | 14382 | 3.18 | ||
Facility
| ||||
hospital | 445529 | 98.62 | 9.05 | Reference |
birth center | 1192 | 0.26 | 1.68 | 0.17 |
home | 4131 | 0.91 | 4.58 | 0.48 |
other | 890 | 0.2 | 12.97 | 1.50 |
Maternal Marital Status
| ||||
Missing | 4 | 0 | ||
Married/inferred married | 253396 | 56.09 | 8.42 | Reference |
Unmarried/inferred unmarried | 198342 | 43.91 | 9.72 | 1.17 |
Maternal Tobacco Use
| ||||
No | 399904 | 88.52 | 8.5 | Reference |
Yes | 45737 | 10.12 | 11.84 | 1.45 |
Missing | 6101 | 1.35 | 20.49 | 2.77 |
Maternal Alcohol Use
| ||||
No | 435079 | 96.31 | 8.71 | Reference |
Yes | 9540 | 2.11 | 13.02 | 1.57 |
Missing | 7123 | 1.58 | 20.84 | 2.76 |
No | 376322 | 83.30 | 7.25 | Reference |
Yes | 75420 | 16.7 | 17.69 | 2.75 |
Individual high risk factors*
| ||||
Lung | 7158 | 1.58 | ||
Cardiac | 1996 | 0.44 | ||
Diabetes | 15686 | 3.47 | ||
Eclampsia | 3881 | 0.86 | ||
Hydramnios/oligohydramnios | 7477 | 1.66 | ||
Chronic hypertension | 3634 | 0.8 | ||
Pregnancy-induced hypertension | 21189 | 4.69 | ||
Incompetent cervix | 703 | 0.16 | ||
Previous preterm infant | 4215 | 0.93 | ||
Rh sensitization | 6032 | 1.34 | ||
Tocolysis | 15749 | 3.49 | ||
Overall Preterm (estgest < 37)
| ||||
No | 410346 | 90.84 | ||
Yes | 40550 | 8.98 | ||
Missing estgest value | 846 | 0.19 | ||
Total exclusions for anomalies**
| 9229 | 2.04 | ||
Multiple births or missing information on number born
| 9950 | 2.20 | ||
Out of state resident***
| 10926 | 2.42 |
Adjusted Odds Ratio
|
95% Confidence Interval
|
p value
| |
---|---|---|---|
Maternal Age
| |||
Reference age = 25-29
| |||
Age Group | |||
<15 | 1.9 | 1.47-2.46 | <0.0001 |
15-19 | 1.22 | 1.15-1.30 | <0.0001 |
20-24 | 1.07 | 1.02-1.13 | 0.0059 |
30-34 | 1.09 | 1.03-1.15 | 0.0037 |
35-39 | 1.25 | 1.17-1.35 | <0.0001 |
>40 | 1.34 | 1.18-1.52 | <0.0001 |
Maternal Education Level
| |||
Reference education level = 9-12 years
| |||
Number of years | |||
<9 | 0.995 | 0.92-1.07 | 0.91 |
13-16 | 0.89 | 0.85-0.93 | <0.0001 |
>16 | 0.82 | 0.76-0.89 | <0.0001 |
Maternal Ethnicity
| |||
Reference ethnicity = White Non-Hispanic
| |||
Asian | 1.23 | 1.05-1.43 | 0.0087 |
Other | 1.49 | 0.76-2.92 | 0.2452 |
White Hispanic | 1.05 | 1.00-1.10 | 0.0372 |
Native American | 0.88 | 0.82-0.95 | 0.0016 |
Black | 1.37 | 1.22-1.54 | <0.0001 |
Normal Risk Pregnancy and Level of Prenatal Care
| |||
Reference level of care = Kotelchuck adequate
| |||
Kotelchuck Index | |||
None | 4.92 | 4.53-5.34 | <0.0001 |
Inadequate | 2.16 | 2.02-2.30 | <0.0001 |
Intermediate | 0.93 | 0.85-1.01 | 0.0728 |
High | 4.95 | 4.66-5.25 | <0.0001 |
High Risk Pregnancy and Level of Prenatal Care
| |||
Kotelchuck Index | |||
None | 14.66 | 12.92-16.64 | <0.0001 |
Inadequate | 4.78 | 4.34-5.26 | <0.0001 |
Intermediate | 2.59 | 2.26-2.97 | <0.0001 |
Adequate | 2.31 | 2.08-2.56 | <0.0001 |
High | 8.42 | 7.83-9.05 | <0.0001 |