35: Placental cord insertion and birthweight discordance in twin pregnancies: results of the national prospective EsPRIT trial

Abstract

ObjectiveTo evaluate the impact of non-central placental cord insertion site on birthweight discordance in monochorionic and dichorionic twin pregnancies.Study DesignThis national prospective trial recruited 981 twin pregnancies in 8 tertiary centres. All placentas were examined following delivery according to a defined protocol. Placental cord insertion (PCI) was documented as central (>2cm from placental margin), marginal (<2cm from placental margin) or velamentous. For the purpose of this analysis birthweight discordance was defined as 20% or greater. Rates of central and non-central (marginal or velamentous) cord insertion were compared in smaller twins of discordant twin pairs and their larger co-twins and concordant controls.Results816 twin pairs were evaluated, 165 monochorionic (MC) and 651 dichorionic (DC) twins. Overall rates of discordant growth did not differ significantly in MC and DC cohorts (19.4% vs 16.4%, p=0.42). In the entire cohort non-central cord insertion was found to be significantly more frequent in smaller twins of discordant pairs than in the larger co-twins or concordant twins (29.8% vs 19.1%, p=0.004). When stratified by chorionicity this observation held true for MC twins, with a non-central cord insertion documented in 50% of smaller twins of discordant pairs compared to 29.5% of controls (p=0.026). Discordant DC twins showed a trend towards increased rates of non-central cord insertion in the smaller twin but this did not reach statistical significance (P = 0.062).ConclusionsNon-central cord insertion and resultant unequal placental sharing contribute significantly to the etiology of birthweight discordance in MC twin pregnancies. Antenatal sonographic delineation of placental cord insertion may be a valuable tool in prediction of birthweight discordance in these high-risk cases. ObjectiveTo evaluate the impact of non-central placental cord insertion site on birthweight discordance in monochorionic and dichorionic twin pregnancies. To evaluate the impact of non-central placental cord insertion site on birthweight discordance in monochorionic and dichorionic twin pregnancies. Study DesignThis national prospective trial recruited 981 twin pregnancies in 8 tertiary centres. All placentas were examined following delivery according to a defined protocol. Placental cord insertion (PCI) was documented as central (>2cm from placental margin), marginal (<2cm from placental margin) or velamentous. For the purpose of this analysis birthweight discordance was defined as 20% or greater. Rates of central and non-central (marginal or velamentous) cord insertion were compared in smaller twins of discordant twin pairs and their larger co-twins and concordant controls. This national prospective trial recruited 981 twin pregnancies in 8 tertiary centres. All placentas were examined following delivery according to a defined protocol. Placental cord insertion (PCI) was documented as central (>2cm from placental margin), marginal (<2cm from placental margin) or velamentous. For the purpose of this analysis birthweight discordance was defined as 20% or greater. Rates of central and non-central (marginal or velamentous) cord insertion were compared in smaller twins of discordant twin pairs and their larger co-twins and concordant controls. Results816 twin pairs were evaluated, 165 monochorionic (MC) and 651 dichorionic (DC) twins. Overall rates of discordant growth did not differ significantly in MC and DC cohorts (19.4% vs 16.4%, p=0.42). In the entire cohort non-central cord insertion was found to be significantly more frequent in smaller twins of discordant pairs than in the larger co-twins or concordant twins (29.8% vs 19.1%, p=0.004). When stratified by chorionicity this observation held true for MC twins, with a non-central cord insertion documented in 50% of smaller twins of discordant pairs compared to 29.5% of controls (p=0.026). Discordant DC twins showed a trend towards increased rates of non-central cord insertion in the smaller twin but this did not reach statistical significance (P = 0.062). 816 twin pairs were evaluated, 165 monochorionic (MC) and 651 dichorionic (DC) twins. Overall rates of discordant growth did not differ significantly in MC and DC cohorts (19.4% vs 16.4%, p=0.42). In the entire cohort non-central cord insertion was found to be significantly more frequent in smaller twins of discordant pairs than in the larger co-twins or concordant twins (29.8% vs 19.1%, p=0.004). When stratified by chorionicity this observation held true for MC twins, with a non-central cord insertion documented in 50% of smaller twins of discordant pairs compared to 29.5% of controls (p=0.026). Discordant DC twins showed a trend towards increased rates of non-central cord insertion in the smaller twin but this did not reach statistical significance (P = 0.062). ConclusionsNon-central cord insertion and resultant unequal placental sharing contribute significantly to the etiology of birthweight discordance in MC twin pregnancies. Antenatal sonographic delineation of placental cord insertion may be a valuable tool in prediction of birthweight discordance in these high-risk cases. Non-central cord insertion and resultant unequal placental sharing contribute significantly to the etiology of birthweight discordance in MC twin pregnancies. Antenatal sonographic delineation of placental cord insertion may be a valuable tool in prediction of birthweight discordance in these high-risk cases.