Table 2.
Pooled risk estimates of fecundability and female alcohol consumption in subgroup results.
| Subgroup analysis | No. of studies | Summary RR (95%CI) | Heterogeneity | Publication bias | P value for Heterogeneity | ||
|---|---|---|---|---|---|---|---|
| P | I 2(%) | Begg’s test | Egger’s test | ||||
| Overall | 19 | 0.87 (0.78, 0.95) | 0.001 | 89.6 | 0.069 | 0.169 | |
| Dose | |||||||
| Non vs. lighter | 15 | 0.89 (0.82, 0.97) | 0.001 | 90.3 | 0.113 | 0.412 | 0549 |
| Non vs. moderate | 14 | 0.77 (0.61, 0.94) | 0.001 | 90.7 | 0.381 | 0.152 | |
| Study design | |||||||
| Cohort | 12 | 0.93 (0.86, 1.00) | 0.001 | 77.3 | 0.732 | 0.761 | 0.157 |
| Case-control | 7 | 0.77 (0.53, 1.01) | 0.001 | 92.6 | 0.230 | 0.040 | |
| Geographical area | |||||||
| Europe | 11 | 0.93 (0.78–1.08) | 0.001 | 90.2 | 0.755 | 0.644 | 0.322 |
| America | 8 | 0.80 (0.67–0.93) | 0.001 | 89.8 | 0.009 | 0.055 | |
| Type of population | |||||||
| General | 8 | 0.87 (0.76, 0.98) | 0.001 | 93.1 | 0.108 | 0.222 | 0.854 |
| Hospital | 5 | 1.00 (0.81, 1.20) | 0.020 | 65.8 | 0.806 | 0.692 | |
| Worker | 3 | 0.65 (0.35, 0.94) | 0.021 | 74.2 | 0.999 | 0.858 | |
| Agricultural | 2 | 0.78 (0.32, 1.25) | 0.001 | 94.1 | 0.999 | — | |
| Nurses | 1 | 1.01 (0.85, 1.17) | — | — | — | — | |
| Women’s mean Age | |||||||
| <25 | 2 | 0.84 (0.69, 1.00) | 0.273 | 16.9 | 0.999 | — | 0.540 |
| 25–30 | 10 | 0.87 (0.72, 1.02) | 0.001 | 91.9 | 0.474 | 0.315 | |
| ≥30 | 5 | 0.84 (0.56, 1.12) | 0.001 | 91.6 | 0.086 | 0.076 | |
| NA | 2 | 0.98 (0.95, 1.00) | 0.970 | 0 | 0.999 | — | |
| Time_exposure | |||||||
| Half-year | 4 | 0.75 (0.42, 1.09) | 0.001 | 95.9 | 0.308 | 0.185 | 0.501 |
| One-year | 9 | 0.95 (0.88, 1.01) | 0.002 | 67.5 | 0.917 | 0.796 | |
| Two-years | 6 | 0.84 (0.60, 1.09) | 0.001 | 87.4 | 0.452 | 0.127 | |
| Definition of outcome | |||||||
| Waiting Time to Pregnancy | 12 | 0.85 (0.73, 0.96) | 0.001 | 92.8 | 0.537 | 0.364 | 0.832 |
| Infertility Occurrence | 5 | 0.91 (0.77, 1.06) | 0.008 | 71.0 | 0.462 | 0.043 | |
| Ovulatory Infertility | 2 | 0.87 (0.60, 1.15) | 0.022 | 80.9 | 0.999 | — | |
| Diagnostic method of outcome | |||||||
| Self-reported | 11 | 0.97 (0.91, 1.03) | 0.001 | 67.5 | 0.876 | 0.792 | 0.043 |
| Clinically-confirmed | 8 | 0.74 (0.55, 0.93) | 0.001 | 88.6 | 0.035 | 0.046 | |
| Type alcoholic | |||||||
| Wine | 5 | 0.98 (0.85, 1.11) | 0.001 | 91.4 | 0.327 | 0.264 | |
| Beer | 5 | 1.02 (0.99, 1.05) | 0.137 | 42.7 | 0.327 | 0.303 | 0.242 |
| Spirits | 5 | 0.92 (0.83, 1.01) | 0.413 | 0 | 0.327 | 0.977 | |
| Method of alcohol consumption assessment | |||||||
| SAQ | 15 | 0.83 (0.73, 0.92) | 0.001 | 91.5 | 0.166 | 0.945 | 0.008 |
| FFQ | 4 | 1.03 (0.95, 1.10) | 0.295 | 19.0 | 0.089 | 0.002 | |
| Quality score | |||||||
| NOS = 8 | 14 | 0.91 (0.79–1.02) | 0.001 | 88.8 | 0.324 | 0.284 | 0436 |
| NOS ≤ 7 | 5 | 0.76 (0.49–1.02) | 0.001 | 92.6 | 0.086 | 0.250 | |
FFQ: Food-Frequency Questionnaire; NA: Not Available; NOS: Newcastle-Ottawa Scale; SAQ: Self-Administered Questionnaire; RR: Risk Ratio.