Little and large: the effects of twin growth discordance

Association between first-trimester uterine artery Doppler and crown-rump length with growth discordance: does it make a difference

OBJECTIVES

The purpose of this study was to investigate the association between first-trimester uterine artery pulsatility index (UtA-PI) and crown-rump length discordance (CRLD) with growth discordance (GD) in twins and analyze the influence of chorionicity in these parameters.

METHODS

This retrospective analysis integrated data from the twin pregnancy database of Centro Hospitalar São João (2019-2023), including 184 fetuses, with 19 monochorionic and 73 dichorionic gestations. To determine the association between UtA-PI and CRLD with GD, correlation analyses were computed and linear regression models were carried out. Separate analyses were conducted for each type of placentation. Logistic regression analysis was carried out to determine the association of mean UtA-PI and CRLD with severe GD, defined as discordance ≥25 %.

RESULTS

GD≥25 % was detected in 9.80 % of pregnancies. A statistically significant difference between monochorionic and dichorionic gestations was found in crown-rump length (p=0.009), CRLD (p<0.001) and birth weight (p=0.025), but not in mean UtA-PI (p=0.853) or GD (p=0.556). Mean UtA-PI was significantly higher in discordant than in concordant pairs (p<0.001), but that association was not seen in CRLD (p=0.931). Mean UtA-PI and GD were correlated by the regression line "GD=3.844 × UtA-PI + 6.638", with R2 0.027. CRLD and GD were correlated by the regression line "GD=0.280 × CRLD + 10.79", with R2 0.010. Mean UtA-PI, but not CRLD, was significantly associated with severe GD (odds ratio, 22.753; p=0.002).

CONCLUSIONS

Mean UtA-PI, but not CRLD, is associated with GD. The prevalence of severe GD increases significantly with increasing mean UtA-PI.

Evaluating the Impact of Maternal Exposure to Ozone on Twin Fetal Growth in China

Unlike singletons, twins require attention not only to the birth weight of the fetuses but also to discordance (i.e., the differences between weights) because twin growth discordance is a significant factor contributing to perinatal mortality and morbidity in twin pregnancies. However, the impact of maternal air pollution exposure on twin growth discordance has rarely been investigated. We examined the association of long-term ozone exposure during preconception and pregnancy with the birth weight of twins and twin growth discordance among 35,795 twins from the National Free Preconception Health Examination Project between January 2010 and December 2019. Linear mixed-effect models and random-effect logistic regression models were used to examine the associations of ozone exposure with the birth weight-related outcomes (i.e., birth weight of twins and within-pair birth weight difference) and risk of twin growth discordance, respectively, after adjustment for demographic characteristics and lifestyle. We found that an interquartile range (IQR) increase (15 μg/m3) in ozone exposure during the entire pregnancy was associated with a reduction (-28.96g, 95% confidence interval [CI]: -46.37, -11.56) in the total birth weight of twins, and ozone had a more pronounced impact on the birth weight of the smaller fetuses (-18.28 g, 95% CI: -27.22, -9.34) compared to the larger fetuses (-9.88 g, 95% CI: -18.84, -0.92) in twin pregnancies. An IQR increase in ozone exposure during the entire pregnancy was associated with a significant increase (8.41 g, 95% CI: 4.13, 12.69) in the within-pair birth weight difference; the odds ratio (OR) of twin growth discordance related to ozone exposure increased by 9% (OR = 1.09, 95% CI: 1.01, 1.18). However, no consistently significant associations were observed for ozone exposure during prepregnancy. Male-male twin pairs and those who were born prematurely appeared to be more susceptible to ozone exposure than their counterparts. Long-term ozone exposure during pregnancy was associated with twin growth discordance, and our findings provide reference data for future studies.

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.

The complex aetiology of cerebral palsy

Cerebral palsy (CP) is the most prevalent, severe and costly motor disability of childhood. Consequently, CP is a public health priority for prevention, but its aetiology has proved complex. In this Review, we summarize the evidence for a decline in the birth prevalence of CP in some high-income nations, describe the epidemiological evidence for risk factors, such as preterm delivery and fetal growth restriction, genetics, pregnancy infection and other exposures, and discuss the success achieved so far in prevention through the use of magnesium sulfate in preterm labour and therapeutic hypothermia for birth-asphyxiated infants. We also consider the complexities of disentangling prenatal and perinatal influences, and of establishing subtypes of the disorder, with a view to accelerating the translation of evidence into the development of strategies for the prevention of CP.