Selective and non-selective intrauterine growth restriction in twin pregnancies: high-risk factors and perinatal outcome

Donor catch-up growth after laser surgery for twin-twin transfusion syndrome

OBJECTIVE

To assess fetal growth after laser surgery for TTTS at the time of prenatal diagnosis, birth, and at 2years of age.

DESIGN/METHODS

Growth data were collected from surviving children treated between 2007 and 2010 as part of a study to assess neurodevelopment at 24months (±6weeks) corrected age. Fetal weights were obtained via ultrasound using Hadlock's formula at the time of preoperative assessment for laser surgery. Birth weights were recorded by the staff at the delivering institutions. Weights at 2years corrected age were recorded at the time of neurodevelopmental testing. Weights were converted into percentiles according to standard growth curves. Growth restriction was defined as <10th percentile for given age. Multilevel latent growth curve models in Mplus (twins nested in families) examined weight change over time as a function of donor status, and repeated measures ANOVA was utilized to assess in donor-recipient weight discordance over time for twin pairs.

RESULTS

99 of 206 children (56 of 130 families) were studied. There were no differences between enrolled and non-enrolled patients in donor/recipient status and survival rates, fetal demise, intrauterine growth restriction, Quintero stage, and gestational age of surgery or delivery. 48.5% were donors. The median fetal, birth, and 2-year weights for all twins were 288g, 1.9kg, and 11.8kg, respectively, and the overall prevalence of growth restriction was 28%, 22%, and 3%, respectively. Growth restriction rates at prenatal diagnosis were 56% in donors vs. 2% in recipients (OR=64.3, p<0.001); at birth, 35% vs. 10% (OR=5.0, p<0.01); and at 2years, 6% vs. 0%. Donors showed significant gains in weight percentile (B=13.1, p<0.001) and a significant decrease in growth restriction rates over time (B=-1.6, p<0.001). Weight discordance between donor and recipient pairs also significantly decreased over time (linear F(1,42)=54.34, p<0.001).

CONCLUSIONS

After laser surgery for TTTS, donor twins exhibit significant catch-up growth by two years of age.

Discordance in fetal biometry and Doppler are independent predictors of the risk of perinatal loss in twin pregnancies

OBJECTIVE

Impaired fetal growth might be better evaluated in twin pregnancies by assessing the intertwin discordance rather than the individual fetal size. The aim of this study was to investigate the prediction of perinatal loss in twin pregnancy using discordance in fetal biometry and Doppler.

STUDY DESIGN

This was a retrospective cohort study in a tertiary referral center. The estimated fetal weight (EFW), umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, cerebroplacental ratio (CPR), and their discordance recorded at the last ultrasound assessment before delivery or demise of one or both fetuses were converted into centiles or multiples of the median (MoM). The discordance was calculated as the larger value-smaller value/larger value. A logistic regression analysis was performed to identify, and adjust for, potential confounders. The predictive accuracy was assessed using receiver-operating characteristic curve analysis.

RESULTS

The analysis included 620 (464 dichorionic diamniotic and 156 monochorionic diamniotic) twin pregnancies (1240 fetuses). Perinatal loss of one or both fetuses complicated 16 pregnancies (2.6%). The combination of EFW discordance and CPR discordance had the best predictive performance (area under the curve, 0.96; 95% confidence interval, 0.92-1.00) for perinatal mortality. The detection rate, false-positive rate, positive likelihood ratio, and negative likelihood ratio were 87.5%, 6.7%, 13.08, and 0.13, respectively. The EFW centile, EFW below the 10th centile (small for gestational age), UA PI discordance, MCA PI discordance, and MCA PI MoM were significantly associated with the risk of perinatal loss on univariate analysis, but these associations became nonsignificant after adjusting for other confounders (P = .097, P = .090, P = .687, P = .360, and P = .074, respectively). The UA PI MoM, CPR MoM, EFW discordance, and CPR discordance were all independent predictors of the risk of perinatal loss, even after adjusting for potential confounders (P = .022, P = .002, P < .001, and P = .010, respectively).

CONCLUSION

EFW discordance and CPR discordance are independent predictors of the risk of perinatal loss in twin pregnancies. Their combination could identify the majority of twin pregnancies at risk of perinatal loss. These findings highlight the importance of discordance in Doppler indices of fetal hypoxia, as well as fetal size, in assessing the risk of perinatal mortality.

Intrauterine growth restriction in monochorionic-diamniotic twins

Objective: to evaluate neonatal morbidity and mortality in monochorionic- -diamniotic (MCDA) twin pregnancies complicated by selective intrauterine growth restriction (sIUGR) and non-selective intrauterine growth resctriction (nsIUGR). Methods: neonatal morbidity parameters and mortality were analyzed in 34 twins with IUGR (< 10th percentile on twins’ growth charts): 18 with sIUGR and 16 with nsIUGR. The sIUGR group was made up of 18 pregnancies in which growth was restricted in only one fetus (n = 18). The nsIUGR group was composed of 8 pregnancies in which both fetuses presented restricted growth (n = 16). Cases of twin-to-twin transfusion syndrome and fetal malformation were not included in the study. Results: the MCDA twin pregnancies with sIUGR had a higher rate of orotracheal intubation (p = 0.001) and mechanical ventilation (p = 0.0006), as well as longer than average fasting time (p = 0.014) compared to those in which the fetuses had nsIUGR. A higher incidence was also observed of types II and III umbilical artery Doppler velocimetry patterns in the sIUGR cases (p = 0.002). There was no significant difference between the two groups as to mortality during pregnancy and the neonatal period (p = 0.09). Conclusion: in MCDA twin pregnancies, sIUGR presents more severe umbilical artery Doppler velocimetry abnormalities and worse morbidity than nsIUGR.

Maternal vitamin D predominates over genetic factors in determining neonatal circulating vitamin D concentrations

BACKGROUND

There are multiple potential regulators of neonatal vitamin D status of environmental, genetic, and epigenetic origins. The relation between these factors and circulating neonatal vitamin D has yet to be fully characterized.

OBJECTIVE

The aim of this study was to examine the relative contribution of genetic factors, maternal circulating 25-hydroxyvitamin D [25(OH)D] concentrations, and the placental methylation level of the gene that encodes the primary catabolic enzyme of active vitamin D [25(OH)D-24-hydroxylase encoded by CYP24A1] to neonatal 25(OH)D concentrations.

DESIGN

We used the classical twin study design to determine the genetic contribution to neonatal 25(OH)D. A total of 86 twin pairs (32 monozygotic and 54 dizygotic twin pairs) were included in this study. Serum 25(OH)D was measured by using a 25(OH)D kit. CYP24A1 promoter DNA methylation was measured by means of matrix-assisted laser desorption time-of-flight mass spectrometry.

RESULTS

Maternal and neonatal 25(OH)D showed a strong association (R² = 0.19). Monozygotic and dizygotic within-pair serum 25(OH)D correlations were similar (R² = 0.71 and 0.67, respectively), which suggested no genetic effect. Placental CYP24A1 methylation did not show an association with maternal or neonatal 25(OH)D concentrations.

CONCLUSIONS

Our results suggest that maternal circulating 25(OH)D is the most significant regulator of neonatal circulating 25(OH)D concentrations, with underlying genetic factors playing a limited role. The placental methylation of the CYP24A1 promoter appears subject to a genetic influence, although no evidence of a relation between the methylation level of this gene and circulating maternal or neonatal 25(OH)D was apparent.