Hydatidiform moles are a pregnancy complication where the fetus fails to develop; instead a tumour forms which may become malignant. Hydatidiform moles arise in about one in 1000 to three in 1000 pregnancies; around 16% become malignant, requiring treatment with chemotherapy. For this reason, hydatidiform moles are removed from the womb when they are diagnosed.
Twin pregnancies with one healthy fetus and one hydatidiform mole are rare (occurring in around 1 in 20,000-100,000 twin pregnancies); women are usually advised to have the pregnancy terminated and the hydatidiform mole removed, to reduce the risk of malignant disease. Some women are reluctant to accept this advice.
Michael Seckl and colleagues from Imperial College School of Medicine, London, UK, assessed 77 such twin pregnancies to establish the risks to the mother and baby of continuing the pregnancy compared with termination. 24 women with a hydatidiform mole and healthy fetus decided to have a termination. 53 women continued with their pregnancies, though two had to have terminations because of severe pre-eclampsia, and 23 had a spontaneous aborted. 28 pregnancies lasted 24 weeks or more, resulting in 20 livebirths. Chemotherapy to treat malignant disease was required in three of 19 women (16%) who chose to have a termination and in 12 of 58 (21%) who did not.
Edward Newlands (one of the investigators) comments: "Our findings, therefore, suggest that women with twin pregnancies complicated by a hydatidiform mole who wish to continue their pregnancy, have a 40% chance of a successful outcome. Moreover, this choice is associated with a relatively small chance of serious obstetric complications and does not seem to increase the risk of developing malignant disease."
Contact: Dr Michael J Seckl, Trophoblastic Disease Unit, Department of Cancer Medicine, Imperial College School of Medicine at Charing Cross Hospital, Fulham Palace Road, LONDON W6 8RF, UK; T) +44 (0)20 8846 1421; F) +44 (0)20 8748 5665; E) firstname.lastname@example.org