The relationship of maternal age to molar pregnancy incidence, risks for chemotherapy and subsequent pregnancy outcome

Abstract

The national registration and treatment service for molar pregnancies in the UK allows for the collection of accurate data on this relatively rare diagnosis. In England and Wales, between 2000 and 2009, 5,793 patients with complete moles and 7,790 with partial moles were registered, compared with a total of 8,242,511 conceptions. The overall molar pregnancy incidence was 1 for every 607 conceptions (complete mole 1:1,423; partial mole 1:1,058), but with major variations with age. For complete moles, the risk varied from < 1:1,000 for ages 18-40, to 1:156 for women aged 45 and 1:8 for those aged 50 and above. The overall risk of requiring chemotherapy after a complete mole was 13.6% and 1.1% for partial mole, while the risk of a further molar pregnancy in the next conception was 1:68 but each of these figures have considerable variations with age. These modern statistics on molar pregnancy risks and outcomes should be of value to clinicians and their patients, while discussing this rare diagnosis.

The hydatidiform mole

“…It is higher in the upper extremes of maternal age, 63% for those aged 13-18 y and 55% to 93% for those aged 41-50 y respectively. 39 However, the study by Savage and Williams 43 provides detailed data regarding the risk of partial and complete molar pregnancies with increasing maternal age and confirms that the risk of partial molar pregnancy varies relatively little with age, while complete molar pregnancies contributing to the main component of the overall increase with age. This work shows that the PHM likely corresponds to fertilization anomalies observed in the general population unlike CHM (PHM are biparental but 2 spermatozoa are fertilizing).…”

“…32,37,38 More generally, it is considered that the risk of an additional mole in the next pregnancy is approximately 5-10 fold higher than the baseline risk for the "normal" population. 39 However, the spontaneous rejection of mole formation has also been observed. Conversely, it is impossible to know whether it is more frequent with PHM.…”

“…40,41 Higher frequencies of molar pregnancies are seen in the upper and lower extremes of maternal age; younger than 13-18 y or older than 45-50 y. 39,42 The ratio of complete to partial moles changes significantly with age. It is higher in the upper extremes of maternal age, 63% for those aged 13-18 y and 55% to 93% for those aged 41-50 y respectively.…”

“…This malignant change in molar pregnancies seems to be associated with the male origin of the DNA. 39 The possibility that heterozygous moles (see above) arising from 2 sperm fertilising the "empty egg" may have a higher risk of malignant change is another observation. 45 Approximately 80% of the HM is self-limiting i.e., prevents itself from becoming invasive.…”

“…61 However, the only clear data is related to maternal age 39 and the previous occurrence of a prior molar pregnancy. 37 The excess risk is rather associated with CHM and less with PHM.…”