Influence of placentation and abnormal cord insertion on discordant growth in twin gestation

Ahn, H K; Yang, K M; Hong, S R; Rheu, H M; Kim, M Y; Han, J R; Choi, K H; Yang, J H; Kim, E S

Abstract

OBJECT: The purpose of the study is to determine whether the type of placentation and abnormal cord insertion can affect discordant growth in twin gestation.
MATERIALS AND METHODS
We investigated 422 sets of structually normal twin delivered at our twin clinic after 26 weeks of gestation from 1995-1997. All cases of placenta were examined for pathologic evaluation during the study periods. The type of placentation was divided into four groups: monochorionic monoamniotic placenta (n=4); monochorionic diamniotic placenta (n=62); dichorionic diamniotic fused placenta (n=163); dichorionic diamniotic separate placenta(n=193). Cord insertion was also divided into three groups: both side abnormal insertion (n=17); either side abnormal insertion (n=101); both side normal insertion (n=304). Intertwin weight discordancy was classified as mild form (15-25%) and severe form (>25%) by the degree of the discrepancy.
RESULTS
The results were as follows: 1. Of these 422 twin sets, 132 (31%) consisted of twin discordancy in weight by 15% or greater (mild form 19%, severe form 12%). 2. There are no significant difference in the frequencies of discordancy between MC twins and DC twins (31.8% vs 31.2%, p=0.97). 3. The prevalence of abnormal cord insertion was 16% and much more frequent in MC placenta than DC placenta (26.5% vs 14%, p=0.001). 4. Although mean gestational age at delivery and mean birth weight were significantly lower in either side abnormal cord insertion group than both side normal cord insertion group (35.7 vs 36.7weeks, p=0.004 : 2317 vs 2475gm, p=0.01), no difference in the frequency of discordancy was observed in these two groups (37.6% vs 29%, p=0.1).
CONCLUSION
The type of placentation and/or abnormal cord insertion were not revealed to affect discordant growth in twin gestation.