Association of fetal growth restriction and stillbirth in twin compared with singleton pregnancies.

OBJECTIVE: Twin pregnancies are at an increased risk of stillbirth compared to singletons. Fetal growth restriction (FGR) is a leading cause of perinatal mortality and morbidity, in both singleton and multiple pregnancies. Whether the contribution of FGR to stillbirth in twin pregnancies differs from that in singletons is yet to be determined. The main aim of this study was to determine the association between FGR and stillbirth in twin compared to singleton pregnancies. The secondary objectives include an assessment of the contribution of FGR to stillbirths, stratified by gestational age at delivery. Furthermore, we aimed to compare the association between FGR and stillbirth in twin pregnancies using the twin-specific versus singleton birthweight charts, stratified by chorionicity. METHODS: This was a cross-sectional study including pregnancies receiving obstetric care and birth at St George's Hospital, London. The exclusion criteria included triplet and higher order pregnancies, those resulting in miscarriage or livebirths at or prior to 23+6 weeks, or had a termination of pregnancy, or with missing data on the gestational age at birth. FGR and small for gestational age (SGA) were defined as birthweight <5th and <10th centile, respectively. While standard logistic regression was used for singleton pregnancies, the association of FGR and SGA designation with stillbirth in twin pregnancies was investigated with mixed-effects logistic regression models. For twin pregnancies, intercepts were allowed to vary for twin pairs to account for inter-twin dependency. Analyses were stratified by gestational age at delivery and chorionicity. RESULTS: The study included 95,342 singleton and 3,576 twin pregnancies. There were 494 (0.52%) stillbirths in singleton and 41 (1.15%) stillbirths in twin pregnancies (17 dichorionic and 24 monochorionic). FGR and SGA were significantly associated with stillbirth in singleton pregnancies, across all gestational ages at delivery (before 32 weeks- SGA: OR 2.36; 95% CI 1.78-3.13, p<0.001 and FGR: OR 2.67; 95% CI 2.02- 3.55, p<0.001; between 32-36 weeks- SGA: OR 2.70; 95% CI 1.71-4.31, p<0.001 and FGR: OR 2.82; 95% CI 1.78- 4.47, p<0.001; above 36 weeks- SGA: OR 3.85; 95% CI 2.83 - 5.21, p<0.001 and FGR: OR 4.43; 95% CI 3.16 - 6.12, p<0.001) A greater proportion of fetuses from twin pregnancies were diagnosed as SGA and FGR when singleton compared to the twin-specific chart was used (48.43% vs. 9.12%, and 36.73% vs. 6.23%, respectively). When stratified by gestational age at delivery, both SGA and FGR determined by the twin-specific charts were associated with significantly increased odds of having a stillbirth for those delivered before 32 weeks (SGA: OR 3.87; 95% CI 1.56-9.50, p=0.003 and FGR: OR 5.26; 95% CI 2.11-13.01, p<0.001), those delivered between 32-36 weeks (SGA: OR 6.67; 95% CI 2.11-20.41, p=0.001 and FGR: OR 9.54; 95% CI 3.01-29.40, p<0.001) and those delivered beyond 36 weeks (SGA: OR 12.68 95% CI 2.47-58,15, p=0.001 and FGR: OR 23.84; 95% CI 4.62-110.25, p<0.001), whereas the association of stillbirth with either SGA or FGR was inconsistent when analysed using singleton charts (before 32 weeks- SGA: p=0.014 and FGR: p=0.005; between 32-36 weeks- SGA: p=0.036 and FGR: p=0.008; above 36 weeks- SGA: p=0.080 and FGR: p=0.063). For dichorionic twins delivered before 32 weeks, the odds of an SGA or FGR fetus having a stillbirth was increased when analysed using twin-specific charts. In contrast, monochorionic twins delivered before 32 weeks showed lower and non-significant associations with stillbirth for both SGA and FGR cases using either twin-specific or singleton charts. In dichorionic twin pregnancies delivered between 32-36 weeks, the OR for stillbirth of SGA using twin birthweight chart was 6.70 (95% CI 0.80-56.46, p=0.059), and using singleton chart was 0.92 (95% CI 0.11-7.71, p=0.934) and statistically non-significant. Similarly, the OR for stillbirth of FGR using twin birthweight chart and singleton chart was 9.59 (95% CI 1.14-81.06, p=0.025), and 1.40 (95% CI 0.17-11.76, p=0.735), respectively. On the other hand, in monochorionic twin pregnancies delivered between 32-36 weeks, the OR for stillbirth of SGA and FGR using twin birthweight chart was 9.37 (95% CI 2.20- 37.72, p=0.001), and 13.55 (95% CI 3.12 - 55.94 p < 0.001) respectively. CONCLUSIONS: Our study demonstrates a significant association between SGA, particularly for FGR, with increased odds of stillbirths in singleton pregnancies across all gestational ages. For twin pregnancies, when twin-specific charts were used, SGA and in particular FGR were associated with a significantly increased risk of stillbirth, across all gestational ages at delivery. This article is protected by copyright. All rights reserved.

Physical examination-indicated cerclage in twin pregnancies compared with singleton pregnancies.

OBJECTIVE: The aim of this study was to compare pregnancy outcomes of physical examination-indicated cerclage in twin and singleton pregnancies with bulging membranes. METHODS: All women with bulging membranes in the second trimester of pregnancy who were admitted to La Fe University and Polytechnic Hospital from January 2009 to January 2022 were included. A total of 128 participants were enrolled, 102 singleton pregnancies and 26 twin pregnancies. All patients underwent an amniocentesis to rule out intra-amniotic inflammation (IL-6 < 2.6 ng/mL). Cerclage was placed in the absence of intra-amniotic inflammation. RESULTS: Compared with singleton gestations, twin pregnancies displayed a significantly higher prevalence of nulliparity and assisted reproductive techniques. The incidence of intra-amniotic inflammation/infection was similar in both groups (68.62% in singleton vs. 65.38% in twin pregnancies). The average gestational age of delivery without cerclage in singleton gestations was 23.83 weeks (95% CI 22.82-24.84) and in twin pregnancies, it was 23.69 weeks (95% CI 21.8-25.57). The average gestational age at delivery among patients with cerclage was 37.27 weeks (95% CI 35.35-39.19) in singleton gestations and 36 weeks (95% CI 33.51-38.63) in twin pregnancies, with no significant differences. Time from diagnosis to delivery in patients with IL-6 < 2.6 ng/mL was 79.88 days, and in those with IL > 2.6 ng/mL was 10.87 days. Gestational age at delivery was significantly higher in both singleton and twin pregnancies with cerclage, compared with those without cerclage (log-rank p < .001). CONCLUSIONS: Singleton and twin pregnancies with bulging membranes behave similarly when cerclage is placed in the absence of intraamniotic inflammation/infection.