Table 1.
Summary of Studies on the Clinical Features of Twins
| Author | Country | Year | Experimental Model | Outcome | Result | Ref. |
|---|---|---|---|---|---|---|
| Svirsky | Israel | 2014 | 147 twins and 110 singleton | MAP and PI Variability | In the twins with preeclampsia, map (mean arterial pressure) was significantly higher than that in the twins without preeclampsia (P < 0.02, one tailed), while the level of Doppler PI (Doppler pulse index) was significantly lower. (P < 0.01, two tailed) | [50] |
| Chen | Japan | 1998 | 24 twins and 99 singleton | PI Variability | The mid-term Doppler PI level of twin pregnancy was lower than that of singleton pregnancy | [51] |
| Mourad | USA | 2021 | 614 twins | The rate of hypertensive disorders of pregnancy in the GDM group | After adjusting for mother’s age, in vitro fertilization treatment, race and pre pregnancy body mass index, the study found that there was no difference in the incidence of hypertension during pregnancy between women with and without gestational diabetes | [52] |
| Mor | Israel | 2020 | 135 twins and 63 singleton | The rate of gestational hypertensive disorders (preeclampsia and gestational hypertension) | Compared with twin pregnancy, the incidence of hypertensive disorder complicating pregnancy (preeclampsia and gestational hypertension) was similar, but the rates of severe preeclampsia trended higher In twins (8 (5.9%) vs 0, p=0.057). | [53] |
| Petersen | Norway | 2020 | 125,708 singleton, 20,668 twins | The rate of gestational hypertensive disorders | The study found that the risk of hypertension in twins after natural pregnancy or assisted reproductive technology was increased, but after assisted reproductive technology pregnancy (risk difference, 1.73 percentage points every 5 years; confidence interval, 95%, 1.35–2.11 percentage points every 5 years) was higher than that in twins after natural pregnancy (risk difference, 0.75 percentage points; confidence interval, 95%, 1.35–2.11 percentage points every 5 years); The confidence interval was 95%, 0.61–0.89 percentage points every five years) | [45] |
| Aviram | Canada | 2018 | 144 twins and 768 singleton | SGA (small for gestational age) and maternal vascular malperfusion (MVM) | Compared with preeclampsia singletons, twins had higher mean birth weight, lower small for gestational age (SGA) and fewer births < 34 weeks and < 32 weeks. The incidences of placental weight < 10% (AOR 0.49, 95% CI 0.33–0.71), fetal vascular pathology (AOR 0.28, 95% CI 0.20–0.39) and fetal vascular perfusion pathology (AOR 0.65, 95% CI 0.45–0.93) were lower. The results support the hypothesis that MVM has little relationship with the pathogenesis of HDP in twin pregnancy, and suggest that other placental or non placental factors are the reasons for the increased risk in twin pregnancy | [54] |
| Francisco | UK | 2017 | 93,297 singleton, 1789 DC twin and in 430 MC twin | The relative risk of preterm PE | The relative risk of pre term PE in DC and MC twins is similar and substantially higher than in singleton pregnancies | [11] |
| Henry | USA | 2013 | 3244 twins | The rates of severe preeclampsia | The severity of preeclampsia in twin pregnancy was higher than that in singleton pregnancy | [46] |
| Foo | Australia | 2012 | 3942 singleton and 214 twins | SGA, The rates of preeclampsia | There was no difference in perinatal mortality | [55] |
| Hiersch | China | 2019 | 333 twins | SGA, The rates of preeclampsia | GDM has a greater impact on MCDA twin pregnancy, manifested as maternal hypertensive disorder complicating pregnancy and SGA | [49] |
| Connolly | USA | 2016 | 63 twin and 339 singleton | Morbidity and mortality by severe preeclampsia. | Mothers and neonates of twin pregnancies complicated by preeclampsia do not appear to have greater morbidity and mortality compared to mothers and neonates of singleton pregnancies. | [57] |
| Foo JY | Australia | 2013 | 214 twin and 3942 singleton | SGA, The rates of preeclampsia | The possibility of PE in twin pregnancy with chronic hypertension was higher than that in singleton pregnancy (P < 0.01). The gestational age of twin pregnancy with PE was earlier (P < 0.001), and SGA was more. | [56] |
| Laine | Norway | 2019 | 16,174 twin | The rate of gestational hypertensive disorders | The risk of preeclampsia in twin pregnancies was higher than previously reported, additionally, the prevalence of preeclampsia in twin pregnancies was three to four times higher than that of singleton pregnancies | [42] |
| Savvidou | UK | 2001 | 171 MC and 495 DC | The incidence of pre-eclampsi | No difference in the risk of preeclampsia between monozygotic chorionic twins and dizygotic chorionic twins | [48] |
Abbreviations: DC, dichorionic; GDM, gestational diabetes mellitus; HDP, hypertensive disorders in pregnancy; MAP, mean arterial pressure; MVM, maternal vascular malperfusion; MC, monochorionic; MCDA, monochorionic diamniotic twin; PI, pulse index; PE, preeclampsia; SGA, small for gestational age.