To explore the appropriate fetal weight of twin pregnancies at different gestational weeks and the association with pregnancy complications and outcomes.

Fetal weight at different gestational weeks and related pregnancy complications and outcomes from 1 225 twin pregnancies, who gave birth at Peking University First Hospital from January 2004 to December 2020, were analyzed in this study, including hypertensive disorders in pregnancy, gestational diabetes mellitus (GDM), fetal growth restriction (FGR), fetal distress, preterm birth and neonatal asphyxia. The appropriate fetal weight of twin pregnancies at different gestational weeks were analysed based on the information from 616 twin pregnancies without complications (except preterm birth), and were expressed as P₁₀~P₉₀. The chi-square test was used to compare the risk of pregnancy complications and adverse outcomes in large for gestational age (LGA), appropriate for gestational age (AGA) and small for gestational age (SGA) twin pregnancies and the difference in incidence of pregnancy complications and adverse outcomes in different years.

The appropriate fetal weights of normal twin pregnancies at 28 to 37 weeks and 38-40 weeks of gestation were 910-1 255 g, 996-1 518 g, 1 105-1 785 g, 1 295-1 825 g, 1 336-2 000 g, 1 754-2 321 g, 1 842-2 591 g, 1 913-2 615 g, 2 150-2 847 g, 2 350-3 130 g and 2 450-3 250 g, respectively. The incidences of hypertensive disorders in pregnancy, FGR, fetal distress and neonatal asphyxia related to SGA twin pregnancies were significantly higher than AGA twin pregnancies (all P<0.05). The incidence of GDM in twin pregnant from 2017 to 2020 was higher than that from 2004 to 2009 or from 2010 to 2016, but the incidence of fetal distress and neonatal asphyxia were lower than those from 2010 to 2016, and the differences were statistically significant (all P<0.05).

The appropriate weights of twin fetuses at different gestational weeks are different from singleton. The incidence of pregnancy complications and adverse outcomes in AGA fetuses is significantly lower than that in SGA fetuses under the specific weight standard for twin fetuses, which could provide a practical basis for clinical management of twin pregnancy.

Pregnancy, twin; Fetal weight; Infant, small for gestational age; Fetal growth retardation; Pregnancy complications