Gender-Specific Antenatal Growth Reference Charts in Monochorionic Twins

Abstract

Objective: To create antenatal gender-specific reference growth charts in uncomplicated monochorionic diamniotic twins. Materials and Methods: This is a prospective longitudinal study in which uncomplicated monochorionic (MC) twin pregnancies were included from 23 + 4 weeks of gestation onwards. Estimated fetal weight (EFW) and biometric parameters (biparietal diameter, head circumference, abdominal circumference, and femur length) were evaluated in both fetuses every 2 weeks using standardized methodology. Maternal and fetal complications were excluded. Charts were fitted for each biometric parameter and EFW in relation to gestational age and fetal gender using multilevel mixed models. Results: The final analysis included a total of 456 ultrasound examinations in 62 MC twins, with a mean of 7 scans per pregnancy (range 5–8). The mean as well as 5th and 95th percentiles of each biometric parameter and EFW were adjusted in relation to gender and gestational age between 24 and 37 weeks of gestation. Male fetuses have higher reference values than females, and the disparity is larger in the upper centiles of the distribution. Discussion: We provide gender-specific reference growth charts for MC twins. We suggest that these charts will improve prenatal MC twin assessment and surveillance, with a more accurate classification of normal or growth-restricted fetuses adjusted per sex.

Uncomplicated Monochorionic Twins: Two Normal Hearts Sharing One Placenta

“…Basic ultrasound evaluation included a detailed anatomical examination, as well as determination of the estimated fetal weight (EFW), fetal weight centile, and amniotic fluid. EFW was calculated using the Hadlock formula [18], and centiles were based on prescriptive curves for singleton [19] and MCDA twin fetuses [20], respectively. Monochorionicity was always confirmed by the presence of a T sign with a single placental mass [21] during the first trimester scan.…”

Development of fetal growth charts in twins stratified by chorionicity and mode of conception: a retrospective cohort study in China

“…Second, our reference charts were based on longitudinal data and adequate sample size, which made it available to develop growth centiles to identify patterns and differences in fetal growth at different gestational ages. [ 15 ] Third, taking both chorionicity and mode of conception into account made our growth reference chart a more reliable and sensitive tool in identifying growth restriction in twins. Fourth, the GAMLSS model has unique advantages in fitting the changing curve over time, which has been applied by WHO to establish child growth standards.…”

Predictive Accuracy of Singleton Versus Customized Twin Growth Chart for Adverse Perinatal Outcome: A Cohort Study

“…SGA was defined as BW < 10th percentile, BW between 10th and 90th was classified as AGA, and BW > 90 percentile was labelled as large for gestational age (LGA). The customized charts for twins used in our study were developed by The Working Group on Fetal Biometric Charts with requirement of at least 2 sets of longitudinal measurements for each pregnancy, including the following: biparietal diameter (BPD), fetal head circumference (HC), abdominal circumference (AC), and femur length (FL) [9]. The estimated fetal weight (EFW) was calculated using Hadlock III formula, which incorporates the HC, AC and FL (Log10 weight = 1.326 − 0.00326 AC × FL + 0.0107 HC + 0.0438 AC + 0.158 FL) [13].…”

“…Monochorionic placentation appears to be an individual pathological factor, as monochorionic twins have lower adjusted birthweights than dichorionic when compared to singleton [8]. Moreover, it has been established that male fetuses have higher growth rate than female ones [9]. Authors of publications on twin growth use either singleton or multiple growth curves, as evidence as to which chart estimates the pace of twin growth more precisely is lacking [10,11].…”