Discordance in fetal biometry and Doppler are independent predictors of the risk of perinatal loss in twin pregnancies.
OBJECTIVE
Impaired fetal growth might be better evaluated in twin pregnancies by assessing the intertwin discordance rather than the individual fetal size. The aim of this study was to investigate the prediction of perinatal loss in twin pregnancy using discordance in fetal biometry and Doppler.


METHODS
This was a retrospective cohort study in a tertiary referral center. The estimated fetal weight (EFW), umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, cerebroplacental ratio (CPR), and their discordance recorded at the last ultrasound assessment before delivery or demise of one or both fetuses were converted into centiles or multiples of the median (MoM). The discordance was calculated as the larger value-smaller value/larger value. A logistic regression analysis was performed to identify, and adjust for, potential confounders. The predictive accuracy was assessed using receiver-operating characteristic curve analysis.


RESULTS
The analysis included 620 (464 dichorionic diamniotic and 156 monochorionic diamniotic) twin pregnancies (1240 fetuses). Perinatal loss of one or both fetuses complicated 16 pregnancies (2.6%). The combination of EFW discordance and CPR discordance had the best predictive performance (area under the curve, 0.96; 95% confidence interval, 0.92-1.00) for perinatal mortality. The detection rate, false-positive rate, positive likelihood ratio, and negative likelihood ratio were 87.5%, 6.7%, 13.08, and 0.13, respectively. The EFW centile, EFW below the 10th centile (small for gestational age), UA PI discordance, MCA PI discordance, and MCA PI MoM were significantly associated with the risk of perinatal loss on univariate analysis, but these associations became nonsignificant after adjusting for other confounders (P = .097, P = .090, P = .687, P = .360, and P = .074, respectively). The UA PI MoM, CPR MoM, EFW discordance, and CPR discordance were all independent predictors of the risk of perinatal loss, even after adjusting for potential confounders (P = .022, P = .002, P < .001, and P = .010, respectively).


CONCLUSIONS
EFW discordance and CPR discordance are independent predictors of the risk of perinatal loss in twin pregnancies. Their combination could identify the majority of twin pregnancies at risk of perinatal loss. These findings highlight the importance of discordance in Doppler indices of fetal hypoxia, as well as fetal size, in assessing the risk of perinatal mortality.
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK. Electronic address: asmakhalil79@googlemail.com.
Asma A
AA
Khalil
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK.
Naila
N
Khan
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK.
Sophie
S
Bowe
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK.
Alessandra
A
Familiari
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK.
Aris
A
Papageorghiou
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK.
Amar
A
Bhide
Fetal Medicine Unit, St George's Hospital, St George's University of London, London, England, UK.
Basky
B
Thilaganathan
D000328:Adult; D001699:Biometry; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging*; D020567:Fetal Weight; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D066087:Perinatal Death; D011247:Pregnancy; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin; D011673:Pulsatile Flow; D012189:Retrospective Studies; D012307:Risk Factors; D018615:Ultrasonography, Doppler, Color; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging*
cerebroplacental ratio; estimated fetal weight; impaired fetal growth; intertwin discordance; twin pregnancies