Development of customized fetal growth charts in twins

doi:10.1016/j.ajog.2016.12.176

American Journal of Obstetrics and Gynecology

Volume 216, Issue 5, May 2017, Pages 514.e1-514.e17

https://doi.org/10.1016/j.ajog.2016.12.176 Get rights and content

Background

Twin gestations are at significantly higher risk of fetal growth restriction in comparison with singletons. Using fetal biometric charts customized for obstetrical and parental characteristics may facilitate an accurate assessment of fetal growth.

Objective

The objective of the study was to construct reference charts for the gestation of fetal biometric parameters stratified by chorionicity and customized for obstetrical and parental characteristics.

Study Design

Fetal biometric measurements obtained from serial ultrasound examinations in uncomplicated twin pregnancies delivering after 36 weeks of gestation were collected by 19 Italian fetal medicine units under the auspices of the Società Italiana di Ecografia Ostetrica e Ginecologica. The measurements acquired in each fetus at each examination included biparietal diameter, head circumference, abdominal circumference, and femur length. Multilevel linear regression models were used to adjust for the serial ultrasonographic measurements obtained and the clustering of each fetus in twin pregnancy. The impact of maternal and paternal characteristics (height, weight, ethnicity), parity, fetal sex, and mode of conception was also considered. Models for each parameter were stratified by fetal chorionicity and compared with our previously constructed growth curves for singletons.

Results

The data set included 1781 twin pregnancies (dichorionic, n = 1289; monochorionic diamniotic, n = 492) with 8923 ultrasonographic examinations with a median of 5 (range, 2–8) observations per pregnancy in dichorionic and 6 in (range, 2–11) monochorionic pregnancies. Growth curves of twin pregnancies differed from those of singletons, and differences were more marked in monochorionic twins and during the third trimester. A significant influence of parental characteristics was found.

Conclusion

Curves of fetal biometric measurements in twins are influenced by parental characteristics. There is a reduction in the growth rate during the third trimester. The reference limits for gestation constructed in this study may provide a useful tool for a more accurate assessment of fetal growth in twin pregnancies.

Section snippets

Study population

This was a retrospective multicentric study performed in 19 Italian units under the auspices of the Società Italiana di Ecografia Ostetrica e Ginecologica (SIEOG; www.sieog.it). All the units had proven expertise in sonographic assessment of fetal growth and were opted in by the steering committee of the study. Data were obtained from the combined ultrasound and delivery databases of each unit for pregnancies delivered between January 2010 and December 2015.

Inclusion criteria were an

Results

Complete ultrasound fetal biometric data were obtained from 1781 twin pregnancies including 1289 DC and 439 MCDA gestations that fulfilled the inclusion criteria. Overall, 8923 ultrasonographic examinations were available (6640 in DC and 2463 in MCDA). The median number of observations per twin pregnancy was 5 in DC (range, 2–8) and 6 in MCDA (range, 2–11). The characteristics of the study population are shown in Table 1. When compared with DC twins, MCDA pregnancies showed a lower incidence of

Principal findings

In a large population of uncomplicated dichorionic and monochorionic twin pregnancies, we documented a different growth pattern in comparison with singleton fetuses, with a flattening of the biometric curve starting at 26–28 weeks of gestation for all biometric parameters. Differences with singleton charts were larger in monochorionic twins, progressively increasing during the third trimester for some parameters such as AC. Moreover, as previously shown in singletons,19, 20 a relationship

Conclusion

In conclusion, this large retrospective study has confirmed that the intrauterine growth of uncomplicated twin pregnancies is reduced in comparison with singletons starting from 26–28 weeks. This reduction is more evident in monochorionic twins. The growth pattern of the fetal biometric parameters is significantly influenced by parental variables and fetal sex. The reference ranges for gestation constructed in this study may provide a useful tool for a more accurate assessment of fetal growth

Acknowledgment

The Società Italiana di Ecografia Ostetrica e Ginecologica (SIEOG) Working Group on Fetal Biometric Charts collaborating authors include the following: D. Arduini, S. Arduino, E. Aiello, S. Boito, C. Celentano, N. Chianchiano, G. Clerici, E. Cosmi, V. D’addario, C. Di Pietro, G. Ettore, E. Ferrazzi, T. Frusca, S. Gabrielli, P. Greco, I. Lauriola, G. M. Maruotti, A. Mazzocco, D. Morano, E. Pappalardo, A. Piastra, M. Rustico, T. Todros, T. Stampalija, S. Visentin, N. Volpe, P. Volpe, and C.

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Cited by (47)

A conditional standard for the customized fetal growth trajectory in twin pregnancy
2024, American Journal of Obstetrics and Gynecology MFM
The difference in the birth weights between twins and singletons grows with advancing gestation. Although many fetal weight standards based on ultrasonographic measurements have been created for tracking fetal growth in twin pregnancies, their applicability to other groups is limited by the fact that they are population specific.
This study aimed to generate conditional centiles for growth assessment of twin fetuses and to compare them with other population-based growth standards for singleton and twin fetuses.
This was a retrospective, longitudinal study of ultrasound-based estimated fetal weight data of normal twin fetuses delivered after 34 weeks of gestation. Linear mixed effects models that adjusted for maternal characteristics, fetal gender, and chorionicity were used to evaluate the relationship between estimated fetal weight and gestational age. The estimated fetal weight reference values were calculated using conditional centile based on the estimated fetal weight at an earlier gestational age. To compare our results with previous studies, fetal growth curves were generated using a formula we created that included maternal characteristics and the estimated fetal weight at 24 weeks of gestation in these studies. In a subgroup analysis of our low-risk twin babies born at full term, we calculated the number of fetuses who were reclassified as being in the bottom 10th percentile using each of the previous population-based standard.
A total of 2644 ultrasounds with a median of 4 scans per fetus from 572 twin pregnancies were included in this analysis. In the cohort, 36% of the fetuses were monochorionic. Maternal age, body mass index, and the interaction between fetal gender and chorionicity were significantly associated with estimated fetal weight. The predicted growth curves matched the growth standard for twins. In our low-risk group, when the singleton standard was used, the incidence of estimated fetal weight <10th percentile was above 20% from gestational week 24 to 38, and this incidence varied when reclassified using other population-based twin standards.
This conditional growth chart was specifically designed to assess fetal growth in twin pregnancies, but it is generalizable to other populations.
Clinical implementation of twin-specific growth charts: still more work to do
2023, American Journal of Obstetrics and Gynecology
Should twin-specific growth charts be used to assess fetal growth in twin pregnancies?
2022, American Journal of Obstetrics and Gynecology
Citation Excerpt :
The relatively asymmetrical growth pattern of twins compared with singletons (as described previously) may also be supportive of this argument. In contrast, some have disagreed with this explanation and argued that twins already demonstrate reduced growth early in the third trimester at a time when nutrient supply across the placenta is unlikely to be a limiting factor.41,60,61 In addition, several studies found that twins diagnosed as SGA based on singleton charts are less likely to have placental histopathological abnormalities than SGA singletons.62–64
One of the hallmarks of twin pregnancies is the slower rate of fetal growth when compared with singleton pregnancies during the third trimester. The mechanisms underlying this phenomenon and whether it represents pathology or benign physiological adaptation are currently unclear. One important implication of these questions relates to the type growth charts that should be used by care providers to monitor growth of twin fetuses. If the slower growth represents pathology (ie, intrauterine growth restriction caused uteroplacental insufficiency), it would be preferable to use a singleton growth chart to identify a small twin fetus that is at risk for perinatal mortality and morbidity. If, however, the relative smallness of twins is the result of benign adaptive mechanisms, it is likely preferable to use a twin-based charts to avoid overdiagnosis of intrauterine growth restriction in twin pregnancies. In the current review, we addressed this question by describing the differences in fetal growth between twin and singleton pregnancies, reviewing the current knowledge regarding the mechanisms responsible for slower fetal growth in twins, summarizing available empirical evidence on the diagnostic accuracy of the 2 types of charts for intrauterine growth restriction in twin pregnancies, and addressing the question of whether uncomplicated dichorionic twins are at an increased risk for fetal death when compared with singleton fetuses. We identified a growing body of evidence that shows that the use of twin charts can reduce the proportion of twin fetuses identified with suspected intrauterine growth restriction by up to 8-fold and can lead to a diagnosis of intrauterine growth restriction that is more strongly associated with adverse perinatal outcomes and hypertensive disorders than a diagnosis of intrauterine growth restriction based on a singleton-based chart without compromising the detection of twin fetuses at risk for adverse outcomes caused by uteroplacental insufficiency. We further found that small for gestational age twins are less likely to experience adverse perinatal outcomes or to have evidence of uteroplacental insufficiency than small for gestational age singletons and that recent data question the longstanding view that uncomplicated dichorionic twins are at an increased risk for fetal death caused by placental insufficiency. Overall, it seems that, based on existing evidence, the of use twin charts is reasonable and may be preferred over the use of singleton charts when monitoring the growth of twin fetuses. Still, it is important to note that the available data have considerable limitations and are primarily derived from observational studies. Therefore, adequately-powered trials are likely needed to confirm the benefit of twin charts before their use is adopted by professional societies.
Chorionicity, birth weight discordance and neonatal morbidity in uncomplicated twin pregnancies delivered from 36 weeks
2022, European Journal of Obstetrics and Gynecology and Reproductive Biology
To investigate the association between chorionicity, birth weight discordance and neonatal morbidity in uncomplicated twin pregnancies progressing to at least 36 weeks of gestation.
This was a retrospective single centre cohort study of all twin pregnancies referred to our twin clinic between 2011 and 2018. Outcome details were obtained from the computerized maternity and neonatal records. The primary outcome was incidence of composite neonatal morbidity according to chorionicity. We also determined the incidence of composite neonatal morbidity in pregnancies with birth weight discordance. Logistic regression was used to identify and adjust for potential confounders.
Three hundred and eighty-five twin pregnancies (286 dichorionic, 99 monochorionic) were included. Gestational age at birth was significantly lower in pregnancies complicated by neonatal morbidity (p = 0.013) compared with those which were not. On multivariable logistic regression analysis, gestational age at birth (p = 0.031) and birth weight discordance (p = 0.004), but not chorionicity (p = 0.626) were independently associated with neonatal morbidity.
In uncomplicated twin pregnancies chorionicity is not associated with neonatal morbidity. Gestational age at birth is the major determinant of neonatal outcome while the clinical impact of weight discordance seems marginally significant.
Management and outcome of twin pregnancies
2022, Twin Research for Everyone: From Biology to Health, Epigenetics, and Psychology
The management of multiple pregnancies during gestation, labor and delivery, which has long been a key skill for the obstetrician, is never more important than in the current era. Multiple pregnancies are increasing globally, in keeping with lyfestyle changes, an increase in maternal age, and in the use of assisted reproductive techniques. However, multiple pregnancies contribute disproportionately to prematurity and perinatal mortality and morbidity. Whereas in the past multiple pregnancy often went undiagnosed until delivery, today improved antenatal management, including ultrasound and monitoring, allow a comprehensive and individualized plan for the mode and timing of each pregnancy control and delivery. Twin pregnancies are at increased risk for preterm birth, intrauterine growth restriction, and other conditions such as hypertensive disorders, gestational diabetes. Monochorionic twins have additional risks for death and morbidity, primarily because of the twin-to-twin transfusion syndrome and congenital abnormalities. In order to develop excellence in the antenatal and perinatal management of multiple pregnancies, it is important to consider several key points: chorionicity, fetus growth, adequate monitoring of pregnancy, fetus presentation, planned timing of delivery, planned place of birth offering the most appropriate intrapartum maternal and fetal monitoring.
Developmental outcomes in small-for-gestational age twins using a singleton vs twin birthweight reference
2021, American Journal of Obstetrics and Gynecology MFM
Citation Excerpt :
Because of the differential growth trajectory of twins and singletons, and because a growth-restricted label in utero may increase the risk of iatrogenic preterm delivery and its complications,7 the overdiagnosis of twins as SGA has led researchers and clinicians to debate the necessity of twin-specific references to evaluate twin birthweight and outcomes. Limited data exist about long-term developmental differences among SGA twins, but researchers have called for the development of twin-specific references in predicting short-term outcomes, such as neonatal morbidity and mortality.8–11 Singleton-specific references may overestimate the risk of serious morbidity and mortality in twins10 and may not predict neonatal morbidity or stillbirth in twins as accurately as twin-specific references.9
Limited data exist about the potential developmental delays in appropriately grown twins; furthermore, twins may be at higher risk of developmental delay than singletons. Small-for-gestational age is a risk factor for developmental delay and is based on singleton birthweight references, which may misclassify small-for-gestational age in a subset of appropriately grown twins.
This study aimed to evaluate the risk of developmental delay in twins classified as small-for-gestational age according to the twin and singleton birthweight references (<10th percentile).
In a birth cohort (2008–2010) of twins (n=1790) and singletons (n=3829) where parents completed Ages & Stages Questionnaires for child development between 4 and 36 months, we used a US population-based birthweight reference to categorize singletons and twins as small-for-gestational age. Uncertain small-for-gestational age twins were defined as small-for-gestational age by a singleton reference (<10th percentile) and not by a twin reference, and twin-reference small-for-gestational age twins were defined as small-for-gestational age by a twin reference. Adjusted generalized linear mixed-effects models were used to estimate the odds of failure on any Ages & Stages Questionnaires domain and on each of the 5 domains (fine motor, gross motor, communication, personal-social, and problem-solving domains); random intercepts accounted for repeated measures and twin clustering.
Compared with non–small-for-gestational age twins (>10th percentile), uncertain small-for-gestational age twins did not have higher odds of Ages & Stages Questionnaires failure (adjusted odds ratio, 1.28; 95% confidence interval, 0.91–1.80). Compared with non–small-for-gestational age singletons, both twin-reference and uncertain small-for-gestational age twins had higher odds of Ages & Stages Questionnaires failure, with the highest risk conferred to twin-reference small-for-gestational age twins (twin-reference adjusted odds ratio, 3.14 [95% confidence interval, 1.94–5.10]; uncertain adjusted odds ratio, 2.35 [95% confidence interval, 1.69–3.26]; P<.01 for trend). Results remained consistent when limiting analyses to term births (≥37 weeks’ gestation).
Although a singleton reference may overestimate small-for-gestational age in twins, the findings indicated that a singleton birthweight reference may be appropriate for twins because it identifies more twins at risk of developmental delay than a twin reference.

View all citing articles on Scopus

: The authors report no conflict of interest.

: Cite this article as: Ghi T, Prefumo F, Fichera A, et al. Development of customized fetal growth charts in twins. Am J Obstet Gynecol 2017;216:514.e1-17.

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Original ResearchObstetricsDevelopment of customized fetal growth charts in twins

Background

Objective

Study Design

Results

Conclusion

Section snippets

Study population

Results

Principal findings

Conclusion

Acknowledgment

Am J Obstet Gynecol

Clinics (Sao Paulo)

BJOG

Am J Obstet Gynecol

Am J Obstet Gynecol

J Obstet Gynaecol Can

Am J Obstet Gynecol

BMC Med

Best Pract Res Clin Obstet Gynaecol

Eur J Obstet Gynecol Reprod Biol

Lancet

Am J Obstet Gynecol

What are the fetal growth patterns of singletons, twins, and triplets in the United States?

Clin Obstet Gynecol

Increased perinatal mortality and morbidity in monochorionic versus dichorionic twin pregnancies: clinical implications of a large Dutch cohort study

BJOG

Customized growth charts for twin gestations to optimize identification of small-for-gestational age fetuses at risk of intrauterine fetal death

Ultrasound Obstet Gynecol

Southwest Thames Obstetric Research Center. Fetal growth reference ranges in twin pregnancy: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort

Ultrasound Obstet Gynecol

Association between reduced stillbirth rates in England and regional uptake of accreditation training in customised fetal growth assessment

BMJ Open

Original Research
Obstetrics
Development of customized fetal growth charts in twins