Kibel M, et al. - The purpose of this study is to address this question by comparing placental findings between small for gestational age (SGA) twins and small for gestational age (SGA) singletons. These outcomes elucidate that the mechanisms underlying decreased fetal growth in dichorionic twins differ from those involved in singletons, and may provide support to the hypothesis that smallness in dichorionic twins may be more benign than in singletons.

Methods

• For this research, they designed a retrospective cohort study.
• This was the study of all SGA non-anomalous newborns from singleton and dichorionic twin pregnancies.
• This study was conducted in a single tertiary referral center between 2002 and 2015.
• In this study, SGA was characterized as birth weight <10th percentile for gestational age according to sex-specific national reference charts.
• Placental findings were compared between SGA twins and SGA singletons and were classified into lesions related to maternal vascular malperfusion, fetal vascular malperfusion, placental hemorrhage and chronic villitis.

Results

• In this study, total of 532 SGA twins and 954 SGA singletons met the inclusion criteria.
• The current study showed that the SGA twins had a higher mean placental weight (371 ± 103 g vs. 319 ± 107, p < 0.001) and a lower fetal-placental ratio (6.0 ± 2.5 vs. 6.7 ± 3.2, p < 0.001) compared with SGA singletons.
• Compared with SGA singletons, SGA twins were less likely to have any placental pathology (aOR 0.37, 95%-CI 0.29-0.46), hypercoiled cord (aOR 0.45, 95%-CI 0.33-0.61), placental weight<10th% (aOR 0.13, 95%-CI 0.08-0.20), maternal vascular malperfusion pathology (aOR 0.24, 95%-CI 0.18-0.30) and fetal vascular malperfusion pathology (aOR 0.62, 95%-CI 0.48-0.82).
• By contrast, SGA twins had higher odds of a marginal or velamentous cord insertion compared with SGA singletons (aOR 13.82, 95%-CI 10.44-18.30).
• Similar significant relationship were seen in subgroups of SGA fetuses with a birth weight below the 5th and 3rd percentile for gestational age.