A case-control study of vanishing twin as a risk factor for cerebral palsy.
It has been hypothesized that cerebral palsy of unknown etiology is the result of the death of an unrecognized co-twin--a vanishing twin--in early gestation. We conducted a case-control study of vanishing twin as a risk factor for cerebral palsy of unknown etiology in women who had an obstetric ultrasound during pregnancy. Among mothers of cases, one of 86 had evidence of a vanishing twin on ultrasound, as compared to two of 381 control mothers (odds ratio [OR] 2.2, 95% confidence interval [CI] 0.2-24.8; p = 0.5). Bleeding in early pregnancy, which may indicate the loss of a co-twin, was reported by 14 case mothers and 46 control mothers (OR 1.6, 95% CI 0.8-3.0; p = 0.3). On the basis of results presented here, the vanishing twin syndrome is unlikely to account for a high proportion of cases of cerebral palsy, but there is insufficient statistical power to draw firm conclusions.
Newton
Robert
R
Epidemiology Unit, Gibson Building, Radcliffe Infirmary, Oxford, OX2 6HE, UK. Rob.Newton@cancer.org.uk
Casabonne
Delphine
D
Johnson
Ann
A
Pharoah
Peter
P
D000328:Adult; D016022:Case-Control Studies; D002547:Cerebral Palsy / Q000000981:diagnostic imaging / Q000209:etiology*; D004200:Diseases in Twins / Q000209:etiology*; D005260:Female; D005327:Fetal Resorption / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D016216:Ultrasonography, Prenatal