Table 2.
Multivariate-adjusted Interaction Between Maternal Age and Prenatal Smoking on the Risk of Preeclampsia in 674,250 Singleton Pregnancies in New York City Between 1995 and 2003
| Maternal Age, years | Total Preeclampsia Cases (N = 25,937) | Isolated Preeclampsia (n = 22,340) | Chronic Hypertension With Preeclampsia (n = 3,597) | |||||||||
| Smoker | Nonsmoker | aORa | 95% CI | Smoker | Nonsmoker | aORa | 95% CI | Smoker | Nonsmoker | aORa | 95% CI | |
| ≤20 | 158 | 4,108 | 0.78 | 0.66, 0.92 | 149 | 3,897 | 0.78 | 0.66, 0.92 | 9 | 211 | 0.80 | 0.41, 1.56 |
| 21–30 | 381 | 10,824 | 0.79 | 0.71, 0.88 | 329 | 9,761 | 0.78 | 0.70, 0.87 | 52 | 1,063 | 0.92 | 0.70, 1.22 |
| 31–40 | 421 | 8,896 | 1.00 | 0.90, 1.10 | 308 | 7,083 | 0.95 | 0.85, 1.07 | 113 | 1,813 | 1.09 | 0.90, 1.32 |
| ≥41 | 54 | 1,095 | 1.08 | 0.81, 1.43 | 31 | 782 | 0.91 | 0.63, 1.31 | 23 | 313 | 1.37 | 0.88, 2.11 |
| Interaction P valueb | 0.003 | 0.070 | 0.388 | |||||||||
Abbreviations: aOR, adjusted odds ratio; CI, confidence interval.
a
The multivariate model included race/ethnicity, maternal age, maternal smoking, maternal education, parity, prepregnancy weight, year of birth, presence of gestational diabetes, and maternal age-by-smoking product term.
b
Wald chi-square P value for 3-df test of the maternal age-by-smoking product term.