Should twin-specific growth charts be used to assess fetal growth in twin pregnancies?

Predicting Adverse Perinatal Outcomes in Dichorionic Twin Pregnancies: A Multicentre Cohort Study

OBJECTIVE

Dichorionic twin pregnancies are associated with increased risks of stillbirth or medically indicated early preterm birth (ePTB) to avoid stillbirths. This study evaluated the predictive value of fetal estimated weight (EFW) and Doppler indices before adverse perinatal outcomes.

DESIGN

Retrospective multicentre cohort study.

SETTING

Three tertiary centres in the UK, Italy and Belgium.

POPULATION

The study included 1294 dichorionic twin pregnancies managed between 2013 and 2023.

METHODS

Univariable and multivariable analyses assessed the association and the predictive accuracy between EFW and Doppler indices taken within 2 weeks of birth or adverse perinatal outcomes.

MAIN OUTCOME MEASURES

Stillbirths (of one or both twins) or medically indicated ePTB before 34 weeks' gestation for fetal indications.

RESULTS

The study identified 58 pregnancies (4.5%) complicated by adverse perinatal outcomes. There were significant differences (all p < 0.001) between twins with adverse perinatal outcomes and liveborn twins for small for gestational age foetuses (89.5% vs. 59.3%), EFW discordance (31.8% vs. 8.4%), umbilical artery (UA) pulsatility index (PI) discordance (39.7% vs. 12.6%) and middle cerebral artery PI discordance (27.6% vs. 13.3%). These associations remained significant after adjusting for maternal characteristics and gestational age. The best predictive model included EFW discordance and UA PI discordance, with an area under the curve of 0.90.

CONCLUSIONS

The integration of intertwin EFW and UA PI discordance can effectively predict stillbirths or the need for medically indicated ePTB. After external validation in larger populations, this model could provide effective risk stratification of dichorionic pregnancies to enable targeted interventions to improve clinical outcomes.

Fetal Body Composition in Twins and Singletons

Importance

An emerging paradigm attributes third-trimester fetal growth deceleration in uncomplicated twin pregnancies to an evolutionary adaptive process. Evaluating longitudinal fetal soft-tissue development may provide important insights into differential fetal growth trajectories between twins and singletons.

Objective

To compare twin vs singleton lean and fat tissue growth across pregnancy.

Design, Setting, and Participants

Prospective cohort study of dichorionic twins and singletons with serial ultrasound scans to chart fetal growth (2009-2013) and collect fetal volume data to measure fat and lean tissue (2015-2019) in 12 US clinical centers. Participants were individuals with singleton (n = 2802 enrolled) and twin (n = 171 pairs enrolled) pregnancies who generally had no chronic disease. Data analysis was performed from September 2023 to June 2024.

Exposure

Twin status.

Main Outcomes and Measures

Abdominal area, maximum abdominal subcutaneous tissue thickness, fractional thigh volume, fractional lean thigh volume, fractional fat thigh volume, midthigh area (including lean and fat components), ratio of fractional fat thigh volume to fractional thigh volume, and ratio of midthigh fat area to midthigh area, measured up to 6 times between 15 and 37 weeks' gestation.

Results

Analyses included 315 twin and 2604 singleton fetuses. The mean (SD) maternal age at delivery was 31.3 (6.1) years for twins and 28.2 (5.5) years for singletons, with a mean (SD) gestational age at delivery of 35.2 (4.2) weeks for twins and 39.2 (1.7) weeks for singletons. Mean twin abdominal measurements were significantly smaller than those of singletons between 25 and 37 weeks' gestation for area (difference at 25 weeks, -48.6 [95% CI, -102.2 to -5.1] mm2; difference at 37 weeks, -480.5 [95% CI, -677.2 to -283.5] mm2) and between 27 and 37 weeks for maximum abdominal subcutaneous tissue thickness (difference at 27 weeks, -0.13 [95% CI, -0.24 to -0.02] mm; difference at 37 weeks, -0.40 [95% CI, -0.68 to -0.13] mm). Beginning at 15 weeks, fractional thigh volumes were significantly smaller for twins (mean fractional thigh volume difference, -0.11 [95% CI, -0.16 to -0.07] cm3; mean fractional fat thigh volume difference, -0.08 [95% CI,-0.12 to -0.05] cm3) relative to singletons, persisting through 37 weeks (mean fractional thigh volume difference, -7.55 [95% CI, -11.76 to -3.34] cm3; mean fractional fat thigh volume difference, -5.60 [95% CI, -8.37 to -2.82] cm3). Mean fractional lean thigh volume was significantly smaller for twins at 15 to 16 and 23 to 36 weeks. For the ratio of fractional fat thigh volume to fractional thigh volume, twins had a 2.7% to 4.2% smaller fat percentage between 15 and 37 weeks compared with singletons.

Conclusions and Relevance

Twins had proportionally less fat tissue accumulation in utero compared with singletons as early as 15 weeks' gestation, when competition for nutritional resources was low. Persistent findings of smaller twin sizes and less fat accumulation across pregnancy support the concept of an early evolutionary adaptive process in otherwise uncomplicated dichorionic twin growth.

Fetal biometry reference ranges derived from prospective twin population and evaluation of adverse perinatal outcome

OBJECTIVES

Ultrasound-derived estimates of fetal size play an integral role in the prenatal management of twin pregnancy. These biometric measurements are conventionally plotted against singleton standards. We sought to establish fetal growth references for abdominal circumference, head circumference, biparietal diameter, femur diaphysis length and estimated fetal weight (EFW) in twin pregnancy. We also aimed to determine whether the performance of a twin fetal growth reference was superior to a singleton reference in the prediction of adverse perinatal outcome in twin pregnancies.

METHODS

This was a retrospective analysis of data collected prospectively in the Evaluation of Sonographic Predictors of Restricted growth in Twins (ESPRiT) study, which was conducted at eight academic perinatal centers in Ireland, all with tertiary neonatal intensive care facilities. Only diamniotic twin pregnancies with two live fetuses were eligible for inclusion. Exclusion criteria were monoamnionicity, congenital abnormality, twin-to-twin transfusion syndrome or previable fetal demise (< 24 weeks' gestation). Using serial ultrasound observations, we applied fractional polynomial multilevel models to derive an equation for fetal centile determination. We compared these centiles with published singleton and twin fetal references, with particular focus on the Fetal Medicine Foundation (FMF) references. Using the last ultrasound examinations before delivery, we determined associations between biometric measures and a composite measure of adverse perinatal outcome (intraventricular hemorrhage, periventricular leukomalacia, hypoxic ischemic encephalopathy, necrotizing enterocolitis, bronchopulmonary dysplasia, sepsis or perinatal death), neonatal intensive care unit admission, preterm delivery (< 34 weeks) and birth-weight discordance ≥ 25%, based on the varied prevalence of these outcomes. We compared our results with the singleton and twin FMF reference ranges and the twin reference of the Southwest Thames Obstetric Research Collaborative (STORK) study.

RESULTS

Among the 948 twin pairs that met the inclusion criteria, 776 (81.9%) dichorionic and 172 (18.1%) monochorionic twin pairs completed the prospective 2-weekly ultrasound surveillance program. Fetal biometric measurements were obtained in 15 274 ultrasound assessments (12 279 in dichorionic and 2995 in monochorionic twin pairs) from serial ultrasound assessments. The median number of ultrasound assessments per pregnancy was 8 (interquartile range, 7-9). Growth trajectories in this cohort were consistent with the FMF and STORK published twin cohorts and notably less consistent with the FMF singleton standard. Compared with the FMF singleton standards, the 50th centiles for twins were greater early in pregnancy and lower later in pregnancy for all biometric measures, in both dichorionic and monochorionic twin pregnancies. This crossover in growth occurred at approximately 28 weeks' gestation for dichorionic twins and earlier for monochorionic twins. The 50th centiles for EFW were comparable to the FMF twin standards for both monochorionic and dichorionic twins, but with lower 10th centiles for dichorionic twins in the third trimester. The current (ESPRiT) twin reference ranges, the STORK twin reference ranges and the FMF twin reference ranges showed larger and statistically significant (P < 0.01) odds ratios for multiple biometric measures and multiple adverse perinatal outcomes, for both monochorionic and dichorionic twins, not observed with the FMF singleton reference standard.

CONCLUSIONS

In this analysis of data from the prospective ESPRiT cohort study, we confirm significant differences between twin fetal growth patterns and singleton standards, consistent with previous studies. Our results also offer some validation of the new FMF reference for EFW in twins. The outcome-based evidence from this study suggests that a twin-specific growth reference should be used in preference to a singleton chart for fetal growth evaluation in twin pregnancy. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Management of twin pregnancies: Remaining challenges and unanswered questions

Several professional societies have published guidelines on twin pregnancies over the past few years. These documents provide recommendations on antenatal surveillance and management of twin pregnancies. At the same time, these guidelines identify several key areas where evidence is limited and additional research is needed. In the present review, we summarize available evidence regarding some of these key areas, including the screening and prevention of preterm birth, the definition and management of fetal growth restriction, the diagnosis and management of gestational diabetes, the optimal maternal gestational weight gain, and the mode and timing of delivery. In addition, we describe several online tools related to these areas that can empower individuals with twin pregnancies and assist care providers in counseling these patients.

Paradox in the research of gestational diabetes mellitus and twin pregnancies: Perspective and future directions

Gestational diabetes mellitus (GDM) is well known to be associated with fetal overgrowth and short- or long-term adverse outcomes in singleton pregnancies; however, its relationship with twin pregnancies remains controversial, posing challenges for clinical management. Despite the heterogeneity in GDM diagnosis and racial differences among populations, two critical issues remain unaddressed. The first issue is methodological, specifically whether data on twins have been analyzed using appropriate approaches. The second issue is the underlying pathophysiology'. Given that both glucose demand and insulin resistance are elevated in twin pregnancies, the optimal level of maternal insulin secretion remains uncertain. In this paper, we summarize the current knowledge on GDM in the context of twin pregnancies, their perinatal outcomes, glucose control, and gestational weight gain management. We then propose methodological considerations for future improvements. Ultimately, we underscore the importance of delving into the glucose requirements of twin pregnancies to gain a profound understanding of their gestational glucose and insulin metabolism. All these questions are key issues in this area, and by answering them we will accelerate the development of high-quality, evidence-based clinical guidelines for GDM management in twin pregnancies.

Vanishing twins, selection in utero, and infant mortality in the United States

Background and Objectives

Research to identify fetal predictors of infant mortality among singletons born in the United States (US) concludes that poorly understood and unmeasured "confounders" produce a spurious association between fetal size and infant death. We argue that these confounders include Vanishing Twin Syndrome (VTS)-the clinical manifestation of selection against frail male twins in utero. We test our argument in 276 monthly conception cohorts conceived in the US from January 1995 through December 2017.

Methodology

We use Box-Jenkins transfer function modeling to test the hypothesis that among infants born from 276 monthly conception cohorts conceived in the US from January 1995 through December 2017, the sex ratio of twins born in the 37th week of gestation will correlate inversely with infant mortality among singleton males born at the 40th week of gestation.

Results

We find support for our hypothesis and infer that the contribution of survivors of VTS to temporal variation in infant mortality among the hardiest of singleton male infants, those born at 40 weeks gestation, ranged from a decrease of about 7% to an increase of about 5% over our 276 monthly conception cohorts.

Conclusions and Implications

We conclude that an evolutionary perspective on fetal loss makes a heretofore "unmeasured confounder" of the relationship between fetal size and infant mortality both explicable and measurable. This finding may help clinicians better anticipate changes over time in the incidence of infant mortality.

Validation of Fetal Medicine Foundation charts for fetal growth in twins: nationwide Danish cohort study

OBJECTIVE

To assess the validity of the Fetal Medicine Foundation (FMF) chorionicity-specific models for fetal growth in twin pregnancy.

METHODS

This was an external validation study of the FMF models using a nationwide Danish cohort of twin pregnancies. The cohort included all dichorionic (DC) and monochorionic diamniotic (MCDA) twin pregnancies with an estimated delivery date between 2008 and 2018, which satisfied the following inclusion criteria: two live fetuses at the first-trimester ultrasound scan (11-14 weeks' gestation); biometric measurements available for the calculation of estimated fetal weight (EFW) using the Hadlock-3 formula; and delivery of two liveborn infants. Validation involved assessing the distributional properties of the models and estimating the mean EFW Z-score deviations. Additionally, the models were applied to pregnancies that delivered preterm and attended non-scheduled visits (complicated pregnancies).

RESULTS

Overall, 8542 DC and 1675 MCDA twin pregnancies met the inclusion criteria. In DC twins, 17 084 fetuses were evaluated at a total of 95 346 ultrasound scans, of which 44.5% were performed at scheduled visits in pregnancies carried to 37 + 0 weeks or later. The median number of growth scans per DC twin fetus from 20 + 0 weeks onwards was four. The model showed good agreement with the validation cohort for scheduled visits in DC twins delivered at 37 + 0 weeks or later (mean ± SD EFW Z-score, -0.14 ± 1.05). In MCDA twins, 3350 fetuses underwent 31 632 eligible ultrasound scans, of which 59.5% were performed at scheduled visits in pregnancies carried to 36 + 0 weeks or later. The median number of growth scans per MCDA twin fetus from 16 + 0 weeks onwards was 10. The model showed favorable agreement with the validation cohort for scheduled visits in MCDA twins delivered at 36 + 0 weeks or later (mean ± SD EFW Z-score, -0.09 ± 1.01). Non-scheduled visits and preterm delivery before 37 + 0 weeks for DC twins and before 36 + 0 weeks for MCDA twins corresponded with smaller weight estimates, which was consistent with the study's definition of complicated pregnancy.

CONCLUSIONS

The FMF models provide a good fit for EFW measurements in our Danish national cohort of uncomplicated twin pregnancies assessed at routine scans. Therefore, the FMF models establish robust criteria for subsequent investigations and potential clinical applications. Future research should focus on exploring the consequences of clinical implementation, particularly regarding the identification of twins that are small-for-gestational age, as they are especially susceptible to adverse perinatal outcome. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Chorionicity and Psychomotor Development From Infancy to Childhood: The Japan Environment and Children's Study

Twins lag behind singletons in their early psychomotor development, but little is known about how chorionicity affects this difference. We compared early psychomotor development in singletons, monochorionic (MC) twins and dichorionic (DC) twins. Our longitudinal data from the Japan Environment and Children's Study (JECS; see Appendix) included 98,042 singletons, 577 MC twins and 1051 DC twins representing the general Japanese population. Chorionicity was evaluated by ultrasound images and complemented by postnatal pathological examinations. Five domains of psychomotor development were evaluated at 6 time points from 6 months to 3 years of age using the Ages and Stages Questionnaires (ASQ-3). The data were analyzed using linear regression models. Twins lagged behind singletons in all areas of psychomotor development during infancy. This gap decreased over time but was still noticeable at 3 years of age. More than half of this difference was attributed to twins having lower birth weight and being born earlier in gestation. MC twins showed slightly delayed development compared to DC twins, but this difference was minor compared to the overall gap between twins and singletons. Twins delay singletons in their early psychomotor development, and this delay is not specific to MC twinning.

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

OBJECTIVES

Twin pregnancies are at higher risk of stillbirth compared to singletons. Fetal growth restriction (FGR) is a major cause of perinatal mortality, but its impact on twins vs singletons remains unclear. The primary objective of this study was to investigate the association of FGR and small-for-gestational age (SGA) with stillbirth in twin compared with singleton pregnancies. A secondary objective was to assess these associations stratified by gestational age at delivery. Furthermore, we aimed to compare the associations of FGR and SGA with stillbirth in twin pregnancies using twin-specific vs singleton birth-weight charts, stratified by chorionicity.

METHODS

This was a retrospective cross-sectional study of pregnancies receiving obstetric care and giving birth between 1999 and 2022 at St George's Hospital, London, UK. The exclusion criteria included triplet and higher-order pregnancies, those resulting in miscarriage or live birth at ≤ 23 + 6 weeks, termination of pregnancy and missing data regarding birth weight or gestational age at birth. Birth-weight data were collected and FGR and SGA were defined as birth weight <5th and <10th centiles, respectively. While standard logistic regression was used for singleton pregnancies, the association of FGR and SGA with stillbirth in twin pregnancies was investigated using mixed-effects logistic regression models. For twin pregnancies, intercepts were allowed to vary for twin pairs to account for intertwin dependency. Analyses were stratified by gestational age at delivery and chorionicity. Statistical significance was set at P ≤ 0.001.

RESULTS

The study included 95 342 singleton and 3576 twin pregnancies. There were 494 (0.52%) stillbirths in singleton and 41 (1.15%) stillbirths in twin pregnancies (17 dichorionic and 24 monochorionic). SGA and FGR were associated significantly with stillbirth in singleton pregnancies across all gestational ages at delivery: the odds ratios (ORs) for SGA and FGR were 2.36 ((95% CI, 1.78-3.13), P < 0.001) and 2.67 ((95% CI, 2.02-3.55), P < 0.001), respectively, for delivery before 32 weeks; 2.70 ((95% CI, 1.71-4.31), P < 0.001) and 2.82 ((95% CI, 1.78-4.47), P < 0.001), respectively, for delivery between 32 and 36 weeks; and 3.85 ((95% CI, 2.83-5.21), P < 0.001) and 4.43 ((95% CI, 3.16-6.12), P < 0.001), respectively, for delivery after 36 weeks. In twin pregnancies, when stratified by gestational age at delivery, both SGA and FGR determined by twin-specific birth-weight charts were associated with increased odds of 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 and 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). However, the association of stillbirth with SGA and FGR in twin pregnancies was non-significant when diagnosis was based on singleton charts (before 32 weeks: SGA, P = 0.014 and FGR, P = 0.005; 32-36 weeks: SGA, P = 0.036 and FGR, P = 0.008; after 36 weeks: SGA, P = 0.080 and FGR, P = 0.063).

CONCLUSION

Our study demonstrates that SGA and, especially, FGR are associated significantly with an increased risk of stillbirth across all gestational ages in singleton pregnancies, and in twin pregnancies when twin-specific birth-weight charts are used. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The relationship between glucose patterns in OGTT and adverse pregnancy outcomes in twin pregnancies

BACKGROUND

Traditional fixed thresholds for oral glucose tolerance test (OGTT) results may inadequately prevent adverse pregnancy outcomes in twin pregnancies. This study explores latent OGTT patterns and their association with adverse outcomes.

METHODS

This study retrospectively analyzed 2644 twin pregnancies using latent mixture models to identify glucose level patterns (high, HG; medium, MG; and low, LG) and their relationship with maternal/neonatal characteristics, gestational age at delivery, and adverse outcomes.

RESULTS

Three distinct glucose patterns, HG, MG, and LG patterns were identified. Among the participants, 16.3% were categorized in the HG pattern. After adjustment, compared with the LG pattern, the HG pattern was associated with a 1.79-fold, 1.66-fold, and 1.32-fold increased risk of stillbirth, neonatal respiratory distress, and neonatal hyperbilirubinemia, respectively. The risk of neonatal ICU admission for MG and HG patterns increased by 1.22 times and 1.32 times, respectively, compared with the LG pattern. As gestational weeks increase, although there is an overlap in the confidence intervals between the HG pattern and other patterns in the restricted cubic splines analysis, the trend suggests that pregnant women with the HG pattern are more likely to face risks of their newborns requiring neonatal intensive care unit admission, and adverse comprehensive outcomes, compared with other patterns. In addition, with age and body mass index increasing in HG mode, gestation weeks at delivery tend to be later than in other modes.

CONCLUSION

Distinct OGTT glucose patterns in twin pregnancies correlate with different risks of adverse perinatal outcomes. The HG pattern warrants closer glucose monitoring and targeted intervention.

Late selective termination in dichorionic twins: comparing late second and third trimester procedures

RESEARCH QUESTION

Do perinatal outcomes of selective termination performed in the late second versus third trimester differ and what risk factors are associated with subsequent preterm birth?

DESIGN

This is a retrospective cohort study of late selective terminations performed in dichorionic twins between 2009 and 2021. Perinatal outcomes were compared between two groups: group A, late second trimester (20.2 to 24.2 weeks, n = 26), and group B, third trimester (≥28.2 weeks, n = 55) selective terminations. Univariate and multivariate analyses were conducted to identify factors associated with post-procedure preterm birth.

RESULTS

In total, 81 dichorionic twin pregnancies were included. There were no pregnancy losses but 16% (13/81) of cases experienced complications. Group A had a higher median birthweight centile (36.5th versus 15th centile, P = 0.002) and lower rates of intrauterine growth restriction (IUGR) and Caesarean delivery (11.5% versus 32.7%, P = 0.04; and 26.9% versus 61.8%, P = 0.003) than group B. Preterm birth rates were similar (46.2% versus 63.6%, P = 0.15). Multiple regression revealed that reduction of the presenting twin and cervical length ≤35 mm were independently associated with post-procedure preterm birth (odds ratio [OR] 8.7, P = 0.001, 95% confidence interval [CI] 2.5-29.8; OR 3.8, P = 0.015, 95% CI 1.3-11).

CONCLUSIONS

Late second trimester selective termination is associated with a higher birthweight centile and lower rates of IUGR and Caesarean delivery, compared with third trimester selective termination. Cervical length 35 mm or less and reduction of the presenting twin are independent risk factors for post-procedural preterm birth. These findings may help determine the optimal time to perform a late selective termination.

Gestational diabetes in twin pregnancies-a pathology requiring treatment or a benign physiological adaptation?

There is level-1 evidence that screening for and treating gestational diabetes in singleton pregnancies reduce maternal and neonatal morbidity. However, similar data for gestational diabetes in twin pregnancies are currently lacking. Consequently, the current approach for the diagnosis and management of gestational diabetes in twin pregnancies is based on the same diagnostic criteria and glycemic targets used in singleton pregnancies. However, twin pregnancies have unique physiological characteristics, and many of the typical gestational diabetes-related complications are less relevant for twin pregnancies. These differences raise the question of whether the greater increase in insulin resistance observed in twin pregnancies (which is often diagnosed as diet-treated gestational diabetes) should be considered physiological and potentially beneficial in which case alternative criteria should be used for the diagnosis of gestational diabetes in twin pregnancies. In this review, we summarize the most up-to-date evidence on the epidemiology, pathophysiology, and clinical consequences of gestational diabetes in twin pregnancies and review the available data on twin-specific screening and diagnostic criteria for gestational diabetes. Although twin pregnancies are associated with a higher incidence of diet-treated gestational diabetes, diet-treated gestational diabetes in twin pregnancies is less likely to be associated with adverse outcomes and accelerated fetal growth than in singleton pregnancies and may reduce the risk for intrauterine growth restriction. In addition, there is currently no evidence that treatment of diet-treated gestational diabetes in twin pregnancies improves outcomes, whereas preliminary data suggest that strict glycemic control in such cases might increase the risk for intrauterine growth restriction. Overall, these findings provide support to the hypothesis that the greater transient increase in insulin resistance observed in twin pregnancies is merely a physiological exaggeration of the normal increase in insulin resistance observed in singleton pregnancies (that is meant to support 2 fetuses) rather than a pathology that requires treatment. These data illustrate the need to develop twin-specific screening and diagnostic criteria for gestational diabetes to avoid overdiagnosis of gestational diabetes and to reduce the risks associated with overtreatment of diet-treated gestational diabetes in twin pregnancies. Although data on twin-specific screening and diagnostic criteria are presently scarce, preliminary data suggest that the optimal screening and diagnostic criteria in twin pregnancies are higher than those currently used in singleton pregnancies.

The smaller firstborn: exploring the association of parity and fetal growth

PURPOSE

To investigate the association of parity with a range of neonatal anthropometric measurements in a cohort of uncomplicated term singleton pregnancies.

METHODS

Retrospective cohort study of patients with a singleton term birth at a single tertiary center (2014-2020) was carried out. The primary exposure was parity. The following neonatal anthropometric measures were considered: birthweight, head circumference, length, ponderal index, and neonatal body mass index (BMI).

RESULTS

A total of 8134 patients met the study criteria, 1949 (24.0%) of whom were nulliparous. Compared with multiparous patients, infants of nulliparous patients had a lower mean percentile for birthweight (43.1 ± 26.4 vs. 48.3 ± 26.8 percentile, p < 0.001), head circumference (44.3 ± 26.4 vs. 48.1 ± 25.5 percentile, p < 0.001), length (52.6 ± 25.1 vs. 55.5 ± 24.6 percentile, p < 0.001), ponderal index (34.4 ± 24.0 vs. 37.6 ± 24.2 percentile, p < 0.001), and BMI (39.1 ± 27.1 vs. 43.9 ± 27.3 percentile, p < 0.001). In addition, infants of nulliparous patients had higher odds of having a small (< 10th percentile for gestational age) birthweight (aOR 1.32 [95% CI 1.12-1.56]), head circumference (aOR 1.54 [95% CI 1.29-1.84]), length (aOR 1.50 [95% CI 1.16-1.94]), ponderal index (aOR 1.30 [95% CI 1.12-1.51]), and body mass index (aOR 1.42 [95% CI 1.22-1.65]). Most neonatal anthropometric measures increased with parity until a parity of 2, where it seemed to reach a plateau.

CONCLUSION

Parity has an independent impact on a wide range of neonatal anthropometric measures, suggesting that parity is associated with both fetal skeletal growth and body composition. In addition, the association of parity with fetal growth does not follow a continuous relationship but instead reaches a plateau after the second pregnancy.

Incidence of neonatal morbidity in small-for-gestational-age twins based on singleton and twin charts

OBJECTIVE

To compare morbidity, as measured by length of stay in the neonatal intensive care unit (NICU), in twin and singleton gestations classified as small-for-gestational age (SGA) according to estimated fetal weight < 10th percentile on twin or singleton growth charts.

METHODS

NICU length of stay was compared in 1150 twins and 29 035 singletons that underwent ultrasound assessment between 35 + 0 and 36 + 6 weeks' gestation. Estimated fetal weight was obtained from measurements of head circumference, abdominal circumference and femur length using the Hadlock formula. Gestational age was derived from the first-trimester crown-rump length measurement, using the larger of the two twins. Singletons and twins were compared in terms of NICU admission rate and length of stay according to classification as SGA by the Fetal Medicine Foundation singleton and twin reference distributions.

RESULTS

The overall proportions of twins and singletons admitted to NICU were similar (7.3% vs 7.4%), but twins tended to have longer lengths of stay in NICU (≥ 7 days: 2.4% vs 0.8%; relative risk (RR), 3.0 (95% CI, 1.6-4.4)). Using the singleton chart, a higher proportion of twins were classified as SGA compared with singletons (37.6% vs 7.0%). However, the proportion of SGA neonates entering NICU was similar (10.2% for twins and 10.1% for singletons) and the proportion of SGA neonates spending ≥ 7 days in NICU was substantially higher for twins compared with singletons (3.7% vs 1.4%; RR, 2.6 (95% CI, 1.4-4.7)).

CONCLUSIONS

When singleton charts are used to define SGA in twins and in singletons, there is a greater degree of growth-related neonatal morbidity amongst SGA twins compared with SGA singletons. Consequently, singleton charts do not inappropriately overdiagnose fetal growth restriction in twins and they should be used for monitoring fetal growth in both twins and singletons. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Selective fetal growth restriction in dichorionic diamniotic twin pregnancy: systematic review and meta-analysis of pregnancy and perinatal outcomes

OBJECTIVE

Most of the published literature on selective fetal growth restriction (sFGR) has focused on monochorionic twin pregnancies. The aim of this systematic review was to report on the outcome of dichorionic diamniotic (DCDA) twin pregnancies complicated by sFGR.

METHODS

MEDLINE, EMBASE and The Cochrane Library databases were searched. The inclusion criteria were DCDA twin pregnancies complicated by sFGR. The outcomes explored were intrauterine death (IUD), neonatal death and perinatal death (PND), survival of at least one and both twins, preterm birth (PTB) (either spontaneous or iatrogenic) prior to 37, 34, 32 and 28 weeks' gestation, pre-eclampsia (PE) or gestational hypertension, neurological, respiratory and infectious morbidity, Apgar score < 7 at 5 min, necrotizing enterocolitis, retinopathy of prematurity and admission to the neonatal intensive care unit (NICU). A composite outcome of neonatal morbidity, defined as the occurrence of respiratory, neurological or infectious morbidity, was also evaluated. Random-effects meta-analysis was used to analyze the data, and results are reported as pooled proportion or odds ratio (OR) with 95% CI.

RESULTS

Thirteen studies reporting on 1339 pregnancies with sFGR and 6316 pregnancies without sFGR were included. IUD occurred in 2.6% (95% CI, 1.1-4.7%) of fetuses from DCDA pregnancies with sFGR and 0.6% (95% CI, 0.3-9.7%) of those from DCDA pregnancies without sFGR, while the respective values for PND were 5.2% (95% CI, 3.5-7.3%) and 1.7% (95% CI, 0.1-5.7%). Spontaneous or iatrogenic PTB before 37 weeks complicated 84.1% (95% CI, 55.6-99.2%) of pregnancies with sFGR and 69.1% (95% CI, 45.4-88.4%) of those without sFGR. The respective values for PTB before 34, 32 and 28 weeks were 18.4% (95% CI, 4.4-38.9%), 13.0% (95% CI, 9.5-17.1%) and 1.5% (95% CI, 0.6-2.3%) in pregnancies with sFGR and 10.2% (95% CI, 3.1-20.7%), 7.8% (95% CI, 6.8-9.0%) and 1.8% (95% CI, 1.3-2.4%) in those without sFGR. PE or gestational hypertension complicated 19.9% (95% CI, 12.4-28.6%) of pregnancies with sFGR and 12.8% (95% CI, 10.4-15.4%) of those without sFGR. Composite morbidity occurred in 28.2% (95% CI, 7.8-55.1%) of fetuses from pregnancies with sFGR and 13.9% (95% CI, 6.5-23.5%) of those from pregnancies without sFGR. When stratified according to the sFGR status within a twin pair, composite morbidity occurred in 39.0% (95% CI, 11.1-71.5%) of growth-restricted fetuses and 29.9% (95% CI, 3.5-65.0%) of appropriately grown fetuses (OR, 1.9 (95% CI, 1.7-3.1)), while the respective values for PND were 3.0% (95% CI, 1.8-4.5%) and 1.6% (95% CI, 0.9-2.6%) (OR, 2.1 (95% CI, 1.0-4.1)). On risk analysis, DCDA pregnancies complicated by sFGR had a significantly higher risk of IUD (OR, 5.2 (95% CI, 3.2-8.6)) and composite morbidity or admission to the NICU (OR, 3.2 (95% CI, 1.9-5.6)) compared to those without sFGR, while there was no difference in the risk of PTB before 34 weeks (P = 0.220) or PE/gestational hypertension (P = 0.210).

CONCLUSIONS

DCDA twin pregnancies complicated by sFGR are at high risk of perinatal morbidity and mortality. The findings of this systematic review are relevant for counseling and management of complicated DCDA twin pregnancies, in which twin-specific, rather than singleton, outcome data should be used. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Birth size, school performance and family social position: a study of 650,000 children

BACKGROUND

Low birth weight (BW) is associated with lower cognitive functioning, but less is known of these associations across the full range of the BW distribution and its components. We analyzed how BW, birth length (BL) and birth ponderal index (BPI, kg/m3) are associated with school performance and how childhood family social position modifies these associations.

METHODS

Medical birth records of all Finnish children born in 1987-1997 were linked to school performance records at 16 years of age (N = 642,425). We used population averaged and within-siblings fixed-effects linear regression models.

RESULTS

BL showed a linear and BW a curvilinear association with school performance whereas for BPI the association was weak. The strongest association was found for BL explaining 0.08% of the variation in school performance in boys and 0.14% in girls. Demographic, gestational and social factors partly explained these associations. Similar but weaker associations were found within sibships. The association of BL with school performance was stronger at lower levels of family social position.

CONCLUSION

BL shows a linear association with school performance and can explain more school performance variation than BW. At the population level, BL can offer useful information on intrauterine environmental factors relevant for cognitive performance.

IMPACT

Birth length is linearly associated with school performance in late adolescence and explains a larger proportion of school performance variation than birth weight. The association between birth length and school performance is stronger in families with lower socio-economic position. At the population level, birth length can offer information on the intrauterine environment relevant for later cognitive performance.

Can growth in dichorionic twins be monitored with individualized growth assessment?

OBJECTIVE

To characterize fetal growth in dichorionic twins using individualized growth assessment (IGA), a method based on individual growth potential estimates.

METHODS

This secondary analysis included 286 fetuses/neonates from 143 dichorionic twin pregnancies that were part of the ESPRiT (Evaluation of Sonographic Predictors of Restricted Growth in Twins) study. The sample was subcategorized according to birth weight into appropriate-for-gestational-age (AGA) (n = 243) and small-for-gestational-age (SGA) (n = 43) cohorts. Serial biometric scans evaluating biparietal diameter, head circumference (HC), abdominal circumference, femur diaphysis length and estimated weight at 2-week intervals were used to evaluate fetal growth, while measurements of birth weight, crown-heel length and HC determined neonatal growth outcome. Six abnormalities (hypoxic ischemic encephalopathy, periventricular leukomalacia, necrotizing enterocolitis, respiratory distress, sepsis and death) constituted the evaluated adverse neonatal outcomes (ANO). IGA was used to: evaluate differences in second-trimester growth velocities between singletons (from a published dataset) and dichorionic twins (138 AGA twins with normal third-trimester growth); describe the degree to which actual third-trimester growth in twins followed expected growth (111 AGA twins, normal fetal growth and neonatal growth outcomes); determine if the fetal growth pathology score 1 (-FGPS1) could detect, quantify and classify twin growth pathology (224 AGA, 42 SGA); and assess the relationship between -FGPS1 and ANO (24 SGA twins with progressive growth restriction confirmed by abnormal neonatal growth outcome).

RESULTS

The differences in second-trimester growth velocity between singletons and twins (means and variances) were small and not statistically significant. Percent deviations from the expected third-trimester size trajectories were within the 95% reference ranges derived from singletons at 95.7% (1677/1752) of timepoints studied. Abnormal growth was detected in 37.9% of AGA twins and 85.7% of SGA twins. Growth restriction was more heterogeneous in AGA twins, while in SGA twins progressive growth restriction was the principal type (66.7%). -FGPS1 patterns previously defined in singletons classified 97.5% of pathological twin cases. In our most severe form of growth restriction (progressive), there were only three (12.5%) ANOs related to growth abnormalities, all in cases with -FGPS1 values more negative than -2.0%. Using these criteria, the frequency of ANO was 33%.

CONCLUSIONS

With respect to growth, dichorionic twins can be considered as two singletons in the same uterus. Normally growing dichorionic twins have the same growth potential as singletons with normal growth outcome. These twins also follow expected third-trimester growth trajectories with the same precision as do singletons. Third-trimester growth pathology can be detected, quantified and classified using -FGPS1 as in singletons. Limited evidence of a relationship between fetal growth abnormalities and adverse neonatal outcome was found. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Glycemic control and neonatal outcomes in twin pregnancies with gestational diabetes mellitus

BACKGROUND

Preliminary data suggest that strict glycemic control in twin pregnancies with gestational diabetes mellitus may not improve outcomes but might increase the risk of fetal growth restriction.

OBJECTIVE

This study aimed to investigate the association of maternal glycemic control with the risk of gestational diabetes mellitus-related complications and small for gestational age in twin pregnancies complicated by gestational diabetes mellitus.

STUDY DESIGN

This was a retrospective cohort study of all patients with a twin pregnancy complicated by gestational diabetes mellitus in a single tertiary center between 2011 and 2020, and a matched control group of patients with a twin pregnancy without gestational diabetes mellitus in a 1:3 ratio. The exposure was the level of glycemic control, described as the proportion of fasting, postprandial, and overall glucose values within target. Good glycemic control was defined as a proportion of values within target above the 50th percentile. The first coprimary outcome was a composite variable of neonatal morbidity, defined as at least 1 of the following: birthweight >90th centile for gestational age, hypoglycemia requiring treatment, jaundice requiring phototherapy, birth trauma, or admission to the neonatal intensive care unit at term. A second coprimary outcome was small for gestational age, defined as birthweight <10th centile or <3rd centile for gestational age. Associations between the level of glycemic control and the study outcomes were estimated using logistic regression analysis and were expressed as adjusted odds ratio with 95% confidence interval.

RESULTS

A total of 105 patients with gestational diabetes mellitus in a twin pregnancy met the study criteria. The overall rate of the primary outcome was 32.4% (34/105), and the overall proportion of pregnancies with a small for gestational age newborn at birth was 43.8% (46/105). Good glycemic control was not associated with a reduction in the risk of composite neonatal morbidity when compared with suboptimal glycemic control (32.1% vs 32.7%; adjusted odds ratio, 2.06 [95% confidence interval, 0.77-5.49]). However, good glycemic control was associated with higher odds of small for gestational age compared with nongestational diabetes mellitus pregnancies, especially in the subgroup of diet-treated gestational diabetes mellitus (65.5% vs 34.0%, respectively; adjusted odds ratio, 4.17 [95% confidence interval, 1.74-10.01] for small for gestational age <10th centile; and 24.1% vs 7.0%, respectively; adjusted odds ratio, 3.97 [95% confidence interval, 1.42-11.10] for small for gestational age <3rd centile). In contrast, the rate of small for gestational age in gestational diabetes mellitus pregnancies with suboptimal control was not considerably different when compared with non-gestational diabetes mellitus pregnancies. In addition, in cases of diet-treated gestational diabetes mellitus, good glycemic control was associated with a left-shift of the distribution of birthweight centiles, whereas the distribution of birthweight centiles among gestational diabetes mellitus pregnancies with suboptimal control was similar to that of nongestational diabetes mellitus pregnancies.

CONCLUSION

In patients with gestational diabetes mellitus in a twin pregnancy, good glycemic control is not associated with a reduction in the risk of gestational diabetes mellitus-related complications but may increase the risk of a small for gestational age newborn in the subgroup of patients with mild (diet-treated) gestational diabetes mellitus. These findings further question whether the gestational diabetes mellitus glycemic targets used in singleton pregnancies also apply to twin pregnancies and support the concern that applying the same diagnostic criteria and glycemic targets in twin pregnancies may result in overdiagnosis and overtreatment of gestational diabetes mellitus and potential neonatal harm.

Fetal Growth and Antenatal Testing in Uncomplicated Multiple Gestations

Multiple gestations experience a slowing of fetal growth in the third trimester and have been described as having a higher risk of growth restriction. Whether this increased diagnosis of fetal growth restriction is physiological or pathologic is controversial. In an attempt to better identify those fetuses most at risk, twin-specific growth charts have been developed and tested. In addition, there are data to suggest that multiple gestations experience an increased risk of unexpected third-trimester stillbirth in apparently uncomplicated pregnancies. This chapter reviews the current data and recommendations for fetal growth assessment, antenatal surveillance, and delivery timing in uncomplicated multiple gestations.

National and international guidelines on the management of twin pregnancies: a comparative review

Twin gestations are associated with increased risk of pregnancy complications. However, high-quality evidence regarding the management of twin pregnancies is limited, often resulting in inconsistencies in the recommendations of various national and international professional societies. In addition, some recommendations related to the management of twin gestations are often missing from the clinical guidelines dedicated to twin pregnancies and are instead included in the practice guidelines on specific pregnancy complications (eg, preterm birth) of the same professional society. This can make it challenging for care providers to easily identify and compare recommendations for the management of twin pregnancies. This study aimed to identify, summarize, and compare the recommendations of selected professional societies from high-income countries on the management of twin pregnancies, highlighting areas of both consensus and controversy. We reviewed clinical practice guidelines of selected major professional societies that were either specific to twin pregnancies or were focused on pregnancy complications or aspects of antenatal care that may be relevant for twin pregnancies. We decided a priori to include clinical guidelines from 7 high-income countries (United States, Canada, United Kingdom, France, Germany, and Australia and New Zealand grouped together) and from 2 international societies (International Society of Ultrasound in Obstetrics and Gynecology and the International Federation of Gynecology and Obstetrics). We identified recommendations regarding the following care areas: first-trimester care, antenatal surveillance, preterm birth and other pregnancy complications (preeclampsia, fetal growth restriction, and gestational diabetes mellitus), and timing and mode of delivery. We identified 28 guidelines published by 11 professional societies from the 7 countries and 2 international societies. Thirteen of these guidelines focus on twin pregnancies, whereas the other 16 focus on specific pregnancy complications predominantly in singletons but also include some recommendations for twin pregnancies. Most of the guidelines are recent, with 15 of the 29 guidelines published over the past 3 years. We identified considerable disagreement among guidelines, primarily in 4 key areas: screening and prevention of preterm birth, using aspirin to prevent preeclampsia, defining fetal growth restriction, and the timing of delivery. In addition, there is limited guidance on several important areas, including the implications of the "vanishing twin" phenomenon, technical aspects and risks of invasive procedures, nutrition and weight gain, physical and sexual activity, the optimal growth chart to be used in twin pregnancies, the diagnosis and management of gestational diabetes mellitus, and intrapartum care.This consolidation of key recommendations across several clinical practice guidelines can assist healthcare providers in accessing and comparing recommendations on the management of twin pregnancies and identifies high-priority areas for future research based on either continued disagreement among societies or limited current evidence to guide care.

Twin charts should be the standard reference to assess growth in twin pregnancy

PURPOSE OF REVIEW

Twin pregnancies are characterized by slower growth velocity compared with singletons, especially during the third trimester and, therefore, tend to be smaller than singletons. Growth surveillance is instrumental in the identification of twin pregnancies at risk of adverse outcomes. Whether the phenomenon of slow growth is an adaptive physiological response or represents pathological growth lag, is controversial. In this review, we focus on the evidence related to the types of growth charts employed for twin pregnancies.

RECENT FINDINGS

Consistent evidence has emerged over the past few years from large independent cohorts in different countries suggesting that twin-specific standards perform better in identifying growth-restricted twin pregnancies at risk of adverse perinatal outcomes, without resulting in an increase in interventions or iatrogenic prematurity.

SUMMARY

The current evidence supports the use of twin-specific reference charts. Concerted efforts should be made to derive prospective evidence from large multicentre studies on various aspects of the implementation of twin-specific standards.

Directive clinique no 442 : Retard de croissance intra-utérin : Dépistage, diagnostic et prise en charge en contexte de grossesse monofœtale

OBJECTIF

Le retard de croissance intra-utérin est une complication obstétricale fréquente qui touche jusqu'à 10 % des grossesses dans la population générale et qui est le plus souvent due à une pathologie placentaire sous-jacente. L'objectif de la présente directive clinique est de fournir des déclarations sommaires et des recommandations pour appuyer un protocole clinique de dépistage, diagnostic et prise en charge du retard de croissance intra-utérin pour les grossesses à risque ou atteintes.

POPULATION CIBLE

Toutes les patientes enceintes menant une grossesse monofœtale. BéNéFICES, RISQUES ET COûTS: La mise en application des recommandations de la présente directive devrait améliorer la compétence des cliniciens quant à la détection du retard de croissance intra-utérin et à la réalisation des interventions indiquées. DONNéES PROBANTES: La littérature publiée a été colligée par des recherches effectuées jusqu'en septembre 2022 dans les bases de données PubMed, Medline, CINAHL et Cochrane Library en utilisant un vocabulaire contrôlé au moyen de termes MeSH pertinents (fetal growth retardation and small for gestational age) et de mots-clés (fetal growth, restriction, growth retardation, IUGR, FGR, low birth weight, small for gestational age, Doppler, placenta, pathology). Seuls les résultats de revues systématiques, d'essais cliniques randomisés ou comparatifs et d'études observationnelles ont été retenus. La littérature grise a été obtenue par des recherches menées dans des sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, des registres d'essais cliniques et des sites Web de sociétés de spécialité médicale nationales et internationales. MéTHODES DE VALIDATION: Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Obstétriciens, médecins de famille, infirmières, sages-femmes, spécialistes en médecine fœto-maternelle, radiologistes et autres professionnels de la santé qui prodiguent des soins aux patientes enceintes. RéSUMé POUR TWITTER: Mise à jour de la directive sur le dépistage, le diagnostic et la prise en charge du retard de croissance intra-utérin pour les grossesses à risque ou atteintes. DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS: Prédiction du retard de croissance intra-utérin Prévention du retard de croissance intra-utérin Détection du retard de croissance intra-utérin Examens en cas de retard de croissance intra-utérin soupçonné Prise en charge du retard de croissance intra-utérin précoce Prise en charge du retard de croissance intra-utérin tardif Prise en charge du post-partum et consultations préconception.

Guideline No. 442: Fetal Growth Restriction: Screening, Diagnosis, and Management in Singleton Pregnancies

OBJECTIVE

Fetal growth restriction is a common obstetrical complication that affects up to 10% of pregnancies in the general population and is most commonly due to underlying placental diseases. The purpose of this guideline is to provide summary statements and recommendations to support a clinical framework for effective screening, diagnosis, and management of pregnancies that are either at risk of or affected by fetal growth restriction.

TARGET POPULATION

All pregnant patients with a singleton pregnancy.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline should increase clinician competency to detect fetal growth restriction and provide appropriate interventions.

EVIDENCE

Published literature in English was retrieved through searches of PubMed or MEDLINE, CINAHL, and The Cochrane Library through to September 2022 using appropriate controlled vocabulary via MeSH terms (fetal growth retardation and small for gestational age) and key words (fetal growth, restriction, growth retardation, IUGR, FGR, low birth weight, small for gestational age, Doppler, placenta, pathology). Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. Grey literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Table A1 for definitions and Table A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, radiologists, and other health care providers who care for pregnant patients.

TWEETABLE ABSTRACT

Updated guidelines on screening, diagnosis, and management of pregnancies at risk of or affected by FGR.

SUMMARY STATEMENTS

RECOMMENDATIONS: Prediction of FGR Prevention of FGR Detection of FGR Investigations in Pregnancies with Suspected Fetal Growth Restriction Management of Early-Onset Fetal Growth Restriction Management of Late-Onset FGR Postpartum management and preconception counselling.

Fetal growth restriction, neonatal morbidity and placental pathology in dichorionic twins-a comparison of twin-specific versus singleton growth charts‏‏

INTRODUCTION

Fetal growth restriction (FGR) in dichorionic diamniotic (DCDA) twin gestations is a known complication associated with adverse neonatal outcomes. The international guidelines have no consensus on whether to use singleton or twin-specific growth charts. Thus, we aimed to compare growth charts in correlation with pregnancy outcomes and placental histopathology.

METHODS

The medical files of all DCDA twin deliveries between 2010 and 2020 were reviewed. Birthweight percentile for gestational age (GA) for each individual neonate was assigned using the updated local singleton and twin-specific growth chart. We then divided the study population into two groups, neonates that were FGR based on the local singleton charts (FGR-singleton group) versus FGR on both twin-specific and singleton charts (FGR-twin group). Placental lesions were classified as lesions related to maternal or fetal malperfusion lesions (MVM, FVM), vascular and villous changes, and inflammatory lesions.

RESULTS

Overall, 185 neonates met the inclusion criteria. The FGR-twin group (59/185) had a higher rate of PE, lower GA at delivery, lower birthweight, and a higher rate of neonatal composite adverse outcomes compared to the FGR-singleton group. Moreover, placental pathology of the FGR-twin group demonstrated a higher rate of MVM lesions (p = 0.035).

DISCUSSION

In our cohort, neonates considered FGR based on twin-specific charts had worse neonatal outcomes with underlying placental insufficiency demonstrated by a higher rate of placental malperfusion vascular lesions. Our findings support using a twin-specific chart to diagnose FGR that is more clinically relevant.

Fetal growth trajectories of small/large for gestational age infants in twin pregnancies

BACKGROUND

Birthweight is the most common and accessible parameter in assessing neonatal perinatal outcomes and in evaluating the intrauterine environment globally. Infants born too large or too small not only may alter the maternal mode of delivery but also may face other long-term disorders, such as metabolic diseases and neurodevelopmental delay. Studies have revealed different growth profiles of large-for-gestational-age and small-for-gestational-age fetuses in singleton pregnancies. However, currently, no research is focused on the growth trajectories of these infants during twin pregnancies, even though they are at a much higher risk of being small for gestational age.

OBJECTIVE

This study aimed to explore fetal growth trajectories of large-for-gestational-age and small-for-gestational-age infants in twin pregnancies to provide strategies for fetal growth management.

STUDY DESIGN

This was a case-control study of all noncomplicated twin pregnancies delivered after 36 weeks of gestation at the Peking University First Hospital between 2012 and 2021. Ultrasound data were recorded every 2 to 4 weeks until delivery. All the infants were divided into large-for-gestational-age, small-for-gestational-age, and appropriate-for-gestational-age groups. Longitudinal fetal growth (estimated fetal weight, abdominal circumference, etc.) was compared among the 3 groups using a linear mixed model, and other maternal and neonatal perinatal outcomes were compared. Receiver operating characteristic curves were used to explore optimal biometric parameters and gestational weeks for predicting small-for-gestational-age infants.

RESULTS

Here, 797 pregnant patients with 1494 infants were recruited, with 59 small-for-gestational-age infants, 1335 appropriate-for-gestational-age infants, and 200 large-for-gestational-age infants. The mean birthweights were 1985.34±28.34 g in small-for-gestational-age infants, 2662.08±6.60 g in appropriate-for-gestational-age infants, and 3231.24±11.04 g in large-for-gestational-age infants. The estimated fetal weight of the 3 groups differed from each other from week 26, with the small-for-gestational-age fetuses weighing 51.946 g less and the large-for-gestational-age fetuses weighing 35.233 g more than the appropriate-for-gestational-age fetuses. This difference increased with gestation; at 39 weeks, the small-for-gestational-age fetuses weighed 707.438 g less and the large-for-gestational-age fetuses weighed 614.182 g more than the appropriate-for-gestational-age fetuses (all P<.05). The small-for-gestational-age group had a significantly higher rate of hospitalization (89.9 %) and jaundice (40.7 %) than the appropriate-for-gestational-age group, whereas the hospitalization rate in the large-for-gestational-age group was significantly lower than the appropriate-for-gestational-age group (7.5% and 2.5%; all P<.05). The fetal weight of the small-for-gestational-age infants with adverse outcomes remained near the 10th percentile of the reference and fell below the 3rd percentile at 34 weeks of gestation. The estimated fetal weight after 30 weeks of gestation had a satisfactory diagnostic value in predicting small-for-gestational-age infants. At 30, 32, 34, and 36 weeks of gestation, the areas under the curve were 0.829, 0.840, 0.929, and 0.889 respectively.

CONCLUSION

The growth patterns of small-for-gestational-age, appropriate-for-gestational-age, and large-for-gestational-age twin fetuses diverged from 26 weeks of gestation and continued to increase until delivery; therefore, closer monitoring is suggested from 26 weeks of gestation for those carrying small fetuses.

Fetal growth disorders in twin gestations

PURPOSE OF REVIEW

Twin gestations account for approximately 3% of all births. Although there appear to be physiologic differences in the third trimester growth of twins compared with singleton gestations, reasons for this remain unclear. As growth-restricted fetuses and neonates are at increased risk for adverse outcomes, there is a clinical need to optimize our ability to delineate normally from pathologically grown twins.

RECENT FINDINGS

Recent studies have addressed current limitations in the way growth restriction is diagnosed in twin gestations. Twin-specific fetal and neonatal growth charts have been shown to decrease the number of cases inappropriately labeled as growth restricted compared with singleton nomograms. In addition, individual growth assessment (IGA) is a promising method of diagnosing pathological growth using each fetus's growth potential rather than a comparison of the estimated fetal weight with population nomograms.

SUMMARY

There is a recent focus on improving our understanding of physiologic and pathologic twin growth. The increased use of twin-specific growth curves is likely to result in a decrease in the incidence of FGR diagnosis among twin gestations and could improve the outcomes of twins currently misclassified as FGR. Future research will hopefully clarify the reasons behind differences seen in twin versus singleton third trimester twin growth.

Fetal Growth Restriction and Long-Term Cardiovascular Morbidity of Offspring in Dichorionic-Diamniotic Twin Pregnancies

Objective: We opted to investigate whether fetal growth restriction (FGR) in dichorionic-diamniotic twins is a risk factor for long-term cardiovascular morbidity in offspring. Study design: A population-based retrospective cohort study, comparing long-term cardiovascular morbidity among FGR and non-FGR twins, born between the years 1991 and 2021 in a tertiary medical center. Study groups were followed until 18 years of age (6570 days) for cardiovascular-related morbidity. A Kaplan-Meier survival curve compared the cumulative cardiovascular morbidity. A Cox proportional hazard model assisted with adjusting for confounders. Results: In this study, 4222 dichorionic-diamniotic twins were included; 116 were complicated with FGR and demonstrated a significantly higher rate of long-term cardiovascular morbidity (4.4% vs. 1.3%, OR = 3.4, 95% CI 1.35-8.78, p = 0.006). The cumulative incidence of long-term cardiovascular morbidity was significantly higher among FGR twins (Kaplan-Meier Log rank test p = 0.007). A Cox proportional-hazard model found an independent association between FGR and long-term cardiovascular morbidity, when adjusted for both birth order and gender (adjusted HR 3.3, 95% CI 1.31-8.19, p = 0.011). Conclusions: FGR in dichorionic-diamniotic twins is independently associated with an increased risk for long-term cardiovascular morbidity in offspring. Therefore, increased surveillance may be beneficial.

Second-trimester growth velocities in twin and singleton pregnancies

OBJECTIVE

Previous small studies used individualized growth assessment (IGA) to characterize prenatal growth velocities of singletons and twins. We aimed to compare second-trimester growth velocities of individual anatomical parameters between monochorionic diamniotic (MCDA) twins, dichorionic diamniotic (DCDA) twins and singleton fetuses in a larger study.

METHODS

This was a study of a novel cohort of 222 MCDA twins and previously published cohorts of 40 DCDA twins and 118 singletons with serial ultrasound data. Fetal biometric measurements of biparietal diameter, head circumference, abdominal circumference and femur diaphysis length from prenatal ultrasound examinations were used to calculate second-trimester growth velocities using direct calculation or linear regression analysis. Linear fit was assessed based on the coefficient of determination (R² ). Mean growth velocities and variances were compared among the three groups.

RESULTS

The majority of cases underwent three second-trimester ultrasound examinations with fetal biometry available. All fetuses had linear growth, with R² > 99% for all parameters. Only 1-2% of all MCDA and DCDA anatomical parameters had abnormal growth velocity scores outside the 95% reference range for singletons. There were no significant differences in mean growth velocity for any parameter between MCDA twins and singletons. Femur diaphysis length growth velocity was significantly lower in DCDA twins than in both MCDA twins and singletons. There were no other significant differences among the groups.

CONCLUSIONS

Expanding on prior work using IGA, we found that second-trimester growth velocity of the four major anatomical parameters overall was similar between twins and singletons and between MCDA and DCDA twins, supporting the use of singleton-derived growth standards for IGA in twins. Twin growth potential appears to be similar to that of singletons in the second trimester, suggesting that subsequent growth divergence may be due to third-trimester physiological or pathological changes in twin pregnancies. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Resolution of preeclampsia after selective termination in discordant twins: A case report and literature review

RATIONALE

Preeclampsia is a major cause of maternal and perinatal morbidity and mortality. Growth discordance is associated with an increased risk of preeclampsia in twin pregnancies. The management of preeclampsia combined with discordant twins is difficult and controversial because of severe maternal conditions and severe growth restriction in 1 twin.

PATIENT CONCERNS

A 34-year-old woman with dichorionic diamniotic twin pregnancy complicated by preeclampsia at 29 weeks of gestation, and 1 twin with severe growth restriction and fetal intracranial hemorrhage.

DIAGNOSIS

The patient developed severe preeclampsia with high blood pressure (>160/100 mm Hg) and proteinuria, hydrothorax and leg edema. Ultrasound examination confirmed growth restriction (weight estimation: 915 g, <1st percentile) and abnormal umbilical flow in 1 twin (twin B), with a normal co-twin (estimated weight: 1693 g) (twin A). Magnetic resonance imaging revealed intracranial hemorrhage in the germinal matrix of twin B.

INTERVENTIONS

Selective termination of twin B by intracardiac injection of potassium chloride was performed at 31 weeks and 2 days' gestation.

OUTCOMES

Symptoms of preeclampsia resolved after selective termination, allowing the pregnancy to be prolonged for nearly 4 weeks. A healthy female infant was delivered at 35 weeks of gestation.

CONCLUSION

Delivery of both fetus is not the only choice for the management for twin pregnancy with severe preeclampsia and discordant twins. Selective termination of the fetus with poor prognosis could be a reasonable treatment choice in carefully selected cases.