Study: 1 in 23 MCDA Twins at Late Risk


Approximately 1 in 23 uncomplicated monochorionic diamniotic twin pregnancies could be at risk for late fetal death, an observational study has shown.

The prospective risk of antepartum stillbirth after 32 weeks in this population appears to be independent of intensive ultrasound surveillance for such complications as twin-twin transfusion syndrome (TTTS) and intrauterine growth restriction, according to lead investigator Olivia Barigye, M.D., of the center for fetal care at Queen Charlotte's and Chelsea Hospital, London, and colleagues (PLoS Med. 2005;2:521–7).

If borne out by additional investigations, the findings could support the practice of elective preterm deliveries in such pregnancies, the authors wrote.

Dr. Barigye and colleagues audited the outcomes of 151 uncomplicated monochorionic diamniotic (MCDA) twin pregnancies seen by the hospital's fetal medicine service over a 12-year period. In all of the pregnancies, fetal growth and amniotic fluid volume were normal, as were the results of biweekly ultrasound studies, suggesting that neither TTTS nor intrauterine growth restriction was present.

Seven of the 151 pregnancies resulted in 10 unexpected fetal deaths within 2 weeks of a normal ultrasound scan at a median gestational age of 34 weeks. Autopsies were conducted for the deaths in five of the seven pregnancies. The autopsies for two double-death cases revealed features suggestive of acute late-onset TTTS. Specifically, postmortem evidence of cardiac hypertrophy was seen in the larger plethoric twins, although no such evidence was noted in ultrasound scans taken within 2 weeks of the intrauterine deaths, the investigators reported.

Although previous studies have suggested the main risk of fetal death in MCDA pregnancies occurred before 24 weeks' gestation, the new data “suggest instead that even intensively monitored, apparently healthy MCDA pregnancies remain at substantial risk of [intrauterine death] after 24 weeks,” the authors wrote.

Notwithstanding the study's small numbers, the findings offer useful information for counseling women and “may be used to inform decisions regarding the optimal timing of delivery,” Dr. Barigye and colleagues said.

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