Comparison of all Irish HM incidence rates
| Parameter | Dublin 3-year audit* (1988–1990) | Cork 3-year audit (2017–2019) | Dublin 10-year audit† (1997–2006) | National Pathology Survey 2019 |
| Denominator | 19 457 Pregnancies | 22 167 Total births | 66 296 Total births | 59 536 Total births |
| POC | 2251 | 1856 | N/A | 6008 |
| HM | 38 | 87 | 262 | 170 |
| HM incidence | 1.95 in 1000 1 in 521 | 3.92 in 1000 1 in 255 | 3.95 in 1000 1 in 253 | 2.86 in 1000 1 in 350 |
| CHM | 10 | 12 | 60 | 47 |
| CHM incidence | 1 in 1945 | 1 in 1846 | 1 in 1105 | 1 in 1266 |
| PHM | 28 | 75 | 202 | 123 |
| PHM incidence | 1 in 695 | 1 in 296 | 1 in 328 | 1 in 484 |
| CHM:PHM ratio | 1:2.8 | 1:6.3 | 1:3.4 | 1:2.6 |
*Jeffers et al.41
†Purandare et al. 42
CHM, complete HM; HM, hydatidiform mole; N/A, not available; PHM, partial HM; POC, product of conception.