Table 2.
Crude and adjusted odds ratios of spontaneous abortion by risk factors of female workers employed in the semiconductor industry
| Pregnancy | SA | Crude | Adjusted | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Model 1a | Model 2b | Model 3c | ||||||||
| (N = 4037) | (N = 529) | OR | (95% CI) | OR | (95% CI) | OR | (95% CI) | OR | (95% CI) | |
| The job held longest | ||||||||||
| FAB | 2314 | 291 (12.6) | 1.15 | 0.81–1.64 | 1.09 | 0.71–1.67 | 1.08 | 0.70–1.66 | 1.08 | 0.64–1.81 |
| PKG | 1372 | 199 (14.5) | 1.36 | 0.94–1.96 | 1.28 | 0.82–1.99 | 1.26 | 0.81–1.97 | 1.24 | 0.72–2.12 |
| Clerical worker | 351 | 39 (11.1) | 1.0 | 1.0 | 1.0 | 1.0 | ||||
| Age at conception (years) | ||||||||||
| ≤29 | 2965 | 354 (11.9) | 1.0 | 1.0 | 1.0 | 1.0 | ||||
| 30–34 | 951 | 141 (14.8) | 1.28 | 1.04–1.58 | 1.35 | 1.08–1.69 | 1.34 | 1.06–1.70 | 1.34 | 1.01–1.78 |
| ≥35 | 121 | 34 (28.1) | 2.88 | 1.91–4.35 | 2.98 | 1.94–4.59 | 2.93 | 1.88–4.55 | 2.95 | 1.79–4.85 |
| BMI at interview (kg/m2) | ||||||||||
| ≤24.9 | 3335 | 421 (12.6) | 1.0 | 1.0 | 1.0 | 1.0 | ||||
| ≥25.0 | 702 | 108 (15.4) | 1.26 | 1.00–1.58 | 1.16 | 0.91–1.48 | 1.15 | 0.90–1.48 | 1.16 | 0.91–1.48 |
| Level of education at interview | ||||||||||
| High school | 1435 | 185 (12.9) | 1.0 | 1.0 | 1.0 | 1.0 | ||||
| College/university | 2602 | 344 (13.2) | 1.03 | 0.85–1.25 | 1.04 | 0.84–1.29 | 1.03 | 0.84–1.28 | 1.08 | 0.87–1.34 |
| Smoking status at interview | ||||||||||
| Non smoker | 3298 | 410 (12.4) | 1.0 | 1.0 | 1.0 | 1.0 | ||||
| Smoker | 739 | 119 (16.1) | 1.35 | 1.08–1.69 | 1.44 | 1.14–1.81 | 1.42 | 1.13–1.80 | 1.37 | 1.08–1.73 |
| Pregnancy outcome prior to pregnancy | ||||||||||
| Primigravida | 2156 | 267 (12.4) | 1.0 | 1.0 | 1.0 | |||||
| Full term delivery | 1334 | 166 (12.4) | 1.01 | 0.82–1.24 | 0.95 | 0.76–1.20 | 0.92 | 0.73–1.16 | ||
| Preterm delivery | 57 | 6 (10.5) | 0.83 | 0.35–1.96 | 0.87 | 0.36–2.09 | 0.84 | 0.35–2.01 | ||
| Spontaneous abortion | 361 | 69 (19.1) | 1.67 | 1.25–2.24 | 1.58 | 1.16–2.15 | 1.53 | 1.12–2.08 | ||
| Induced abortion | 103 | 15 (14.6) | 1.21 | 0.69–2.12 | 0.79 | 0.40–1.56 | 0.81 | 0.41–1.59 | ||
| Stillbirth | 26 | 6 (23.1) | 2.12 | 0.84–5.33 | 1.63 | 0.59–4.49 | 1.70 | 0.62–4.70 | ||
| Duration of employment at conception (years) | ||||||||||
| ≤4 | 872 | 93 (10.7) | 1.0 | 1.0 | ||||||
| 5–9 | 1962 | 268 (13.7) | 1.33 | 1.03–1.70 | 1.26 | 0.97–1.65 | ||||
| ≥10 | 1203 | 168 (14.0) | 1.36 | 1.04–1.78 | 1.08 | 0.76–1.52 | ||||
| Year of conception | ||||||||||
| ≥2009 | 2545 | 372 (14.6) | 1.0 | 1.0 | ||||||
| ≤2008 | 1492 | 157 (10.5) | 0.69 | 0.56–0.84 | 0.80 | 0.64–1.00 | ||||
| Study plant | ||||||||||
| A plant | 2383 | 313 (13.1) | 1.0 | 1.0 | ||||||
| B plant | 1654 | 216 (13.1) | 0.99 | 0.82–1.20 | 1.01 | 0.82–1.23 | ||||
| Work schedule | ||||||||||
| Days only | 659 | 82 (12.4) | 1.0 | 1.0 | ||||||
| Rotating shift | 3378 | 447 (13.2) | 1.07 | 0.83–1.38 | 0.97 | 0.69–1.38 | ||||
FAB fabrication process worker, PKG package process worker
Smokers included current and former smokers
SA spontaneous abortion, OR odds ratio, CI confidence interval
Values displaying significant differences are shown in bold (p-value ≤ 0.05)
aMultiple logistic regression model adjusted for the job held longest, age, BMI, education, smoking
bMultiple logistic regression model adjusted for the job held longest, age, BMI, education, smoking, pregnancy outcome just prior to pregnancy
cMultiple logistic regression model adjusted for the job held longest, age, BMI, education, smoking, pregnancy outcome prior to pregnancy, duration of employment, year of conception, study plant, shift work