Table 3. Risk Ratios and 95% CIs for Adverse Birth Outcomes in Individuals Living Within or Near a Hydraulic Fracturing Site During Preconception Compared With Those Unexposed .
| Outcome | Timing of exposure | RR (95% CI) | |
|---|---|---|---|
| Crude | Adjusteda | ||
| Spontaneous preterm birth | Unexposed | 1 [Reference] | 1 [Reference] |
| Preconception | 1.17 (0.98-1.40) | 1.18 (0.99-1.40) | |
| Pregnancy | 0.93 (0.77-1.12) | 0.92 (0.77-1.12) | |
| Both | 0.87 (0.74-1.01) | 0.88 (0.75-1.03) | |
| Indicated preterm birth | Unexposed | 1 [Reference] | 1 [Reference] |
| Preconception | 1.16 (0.92-1.47) | 1.12 (0.89-1.41) | |
| Pregnancy | 0.79 (0.60-1.04) | 0.78 (0.59-1.02) | |
| Both | 1.09 (0.90-1.31) | 1.08 (0.90-1.30) | |
| Small for gestational age | Unexposed | 1 [Reference] | 1 [Reference] |
| Preconception | 0.99 (0.84-1.17) | 0.99 (0.84-1.17) | |
| Pregnancy | 1.15 (1.00-1.32) | 1.14 (0.99-1.32) | |
| Both | 1.19 (1.06-1.33) | 1.18 (1.05-1.33) | |
| Major congenital anomalies | Unexposed | 1 [Reference] | 1 [Reference] |
| Preconception | 1.32 (0.84-2.08) | 1.34 (0.86-2.11) | |
| Pregnancy | 1.42 (0.93-2.18) | 1.43 (0.94-2.19) | |
| Both | 1.22 (0.85-1.74) | 1.19 (0.83-1.70) | |
| Severe neonatal morbidity or mortality | Unexposed | 1 [Reference] | 1 [Reference] |
| Preconception | 1.04 (0.90-1.21) | 1.05 (0.91-1.22) | |
| Pregnancy | 0.88 (0.75-1.03) | 0.89 (0.76-1.05) | |
| Both | 1.16 (1.04-1.30) | 1.19 (1.07-1.33) | |
Abbreviation: RR, risk ratios.
a
All modified Poisson regression models adjusted for parental age at delivery, area-level socioeconomic status, multiple births, infant sex, and obstetric comorbidities.