DOI: 10.1097/01.aoa.0000326398.59896.a6

,  

Issn Print: 0275-665X

Publication Date: 2008/09/01


Print

Increased Perinatal Mortality and Morbidity in Monochorionic Versus Dichorionic Twin Pregnancies: Clinical Implications of a Large Dutch Cohort Study

K.E.A. Hack; J.B. Derks; S.G. Elias; A. Franx; E.J. Roos; S.K. Voerman; C.L. Bode; C. Koopman-Esseboom; G.H.A. Visser

    loading  Checking for direct PDF access through Ovid

Excerpt

Perinatal mortality and morbidity rates in twin pregnancies are 3 to 7 times higher than in singleton births due to more frequent antepartum complications, preterm birth, and uteroplacental insufficiency. Monochorionic (MC) twins have an increased risk for mortality/morbidity when compared with dichorionic (DC) twins due to hemodynamic imbalances seen with monochorionicity. Mortality in uncomplicated MC twin pregnancies is not easily foreseen, despite fetal surveillance. This cohort study examined pregnancy outcomes in MC versus DC pregnancies. In particular, risks associated with fetal death after 32 weeks are controversial, so the data were examined to find an explanation for fetal death in this gestational age with the aim to identify risk factors for adverse outcome and to estimate the optimal time of delivery.
The medical records of all sets of twins (n=1407) delivered for the period from 1995 to 2004 at 2 medical centers in The Netherlands were reviewed. Neonatal and maternal outcomes were compared according to chorionicity, which was determined from the first trimester ultrasound assessment or postpartum pathologic examination of placentas and intertwin membranes. After exclusion of pregnancies with unknown chorionicity, monoamnionicity, removal of one twin, pregnancy loss <20 weeks, first trimester termination, twin-twin transfusion syndrome, and major lethal chromosomal or congenital malformations, 198 MC twin pregnancies were compared to 1107 DC pregnancies.
Among the 1305 pregnancies, MC and DC twins did not differ regarding maternal age, parity, or sex distribution. Median gestational age was 1 week longer in DC twins (P<0.001) and mean birth weight was 221 g higher, but did not differ when compared to MC twins after adjustment for gestational age. Severe birth weight discordancy occurred more often in MC twins [odds ratio 1.23; 95% confidence interval (CI), 0.97-1.55; P=0.094]. Perinatal mortality rates (≥20 wk gestation) were 11.6% and 5.0% in the MC and DC twins, respectively (P<0.001). Stillbirth rates were 7.6% and 1.5% in the MC and DC twins, respectively (hazard ratio 5.21; 95% CI, 3.18-8.51). Incidences of neonatal death did not differ substantially between the groups. At all gestational ages, perinatal mortality was higher in MC twins. Neonatal nursery care was required for 80% of the MC twins and 66% of DC twins and intensive care in 29.4% and 19.5%, respectively (P<0.0001). Neonatal morbidity was higher in MC twins, but when adjusted for gestational age and birth weight, only necrotizing enterocolitis occurred significantly more often in MC twins than in DC twins (odds ratio 4.05; 95% CI, 1.97-8.35). The intrauterine death rate in pregnancies continuing after 32 weeks was 2.1% in MC twins and 0.3% in DC twin pregnancies, but the incidence of neonatal mortality did not differ between the groups in this gestational age subset. At 37 weeks and beyond, intrauterine survival of MC twins decreased but survival of DC twins remained high.
This is the largest cohort of twin pregnancies reported, which examines the relationship of adverse outcomes to chorionicity. Compared with DC twins, MC twins are at increased risk for perinatal death, necrotizing enterocolitis, and neurologic injury. MC twins have an excess rate of intrauterine demise after 32 weeks compared to DC twins. Because current antenatal surveillance will not identify cases at increased risk, planned delivery at 36 weeks' gestation is recommended for MC twins.

Related Topics

    loading  Loading Related Articles