Growth abnormalities and multiple gestations

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.

Birth weight discordance and adverse neonatal outcomes in appropriately grown premature twins

Objective

This study aimed to analyze the clinical characteristics of birth weight discordant twins (BWDT) who were premature and appropriate-for-gestational-age or large-for-gestational-age. Additionally, it assessed the impact of birth weight discordance on the prognosis of appropriately grown premature twins, and investigated the effect of maternal factors on neonatal outcomes.

Study design

This retrospective cohort study included twins who were born alive after preterm labor at the Nanjing Drum Tower Hospital from January 2018 to December 2021, along with their mothers. Twins were arranged into discordant and concordant groups according to intertwin birth weight discordance, followed by the analysis of the clinical characteristics of mothers and the prognosis of neonates.

Results

A total of 585 mothers and 1170 neonates were included, with 47 mothers and 94 neonates in the discordant group. The incidence of birth weight discordance was 8.0% (94/1,170) in appropriately grown premature twins. The incidence of complications (43.2% vs. 21.8%) and transfer to the neonatal intensive care unit (NICU) (53.2% vs. 29.2%) was higher in the discordant group than in the concordant group (p < 0.05). Furthermore, the incidence of infectious diseases (36.7% vs. 19.4%), necrotizing enterocolitis (7.6% vs. 1.6%), and oxygen therapy rate (22.8% vs. 12.8%) were statistically significantly higher in the discordant group than in the concordant group (p < 0.05).

Conclusion

Birth weight discordance remains a high-risk factor for complications and transfer to the NICU in appropriately grown premature twins. It is important to pay attention to birth weight discordance when the outcomes of twins are assessed.

Accuracy of sonographic fetal weight estimation and prediction of birth-weight discordance in twin pregnancy: large single-center study

OBJECTIVES

To determine the accuracy of sonographic fetal weight estimation in predicting birth weight (BW) and BW discordance in twin gestations, and to evaluate maternal and fetal characteristics that may affect the accuracy of this assessment.

METHODS

This was a retrospective cohort study of all twins delivered at a single tertiary medical center between 2010 and 2021. Twin gestations for which sonographic estimation of fetal weight was performed within the week preceding delivery were included. Statistical analysis was performed to evaluate the strength of the correlation between sonographic estimated fetal weight (EFW) and BW, and to determine the impact of maternal and fetal factors on the accuracy of sonographic estimation.

RESULTS

The study included 2154 twin pregnancies. There was a strong correlation between sonographic EFW and corresponding BW for all twins (r = 0.922; P < 0.001). Strong correlations were observed for both the presenting and non-presenting cotwin (r = 0.921 and r = 0.922, respectively; both P < 0.001), as well as the larger and smaller cotwin (r = 0.928 and r = 0.934, respectively; both P < 0.001). The overall mean ± SD absolute error of sonographic EFW was 7.41 ± 6.81%. This error was greater for the non-presenting cotwin compared with the presenting cotwin (7.99 ± 6.12% vs 7.17 ± 5.64%; P < 0.001), and for the smaller cotwin compared with the larger cotwin (8.56 ± 7.50% vs 6.58 ± 5.47%; P < 0.001). Advanced gestational age at scanning was correlated inversely with the mean absolute error of sonographic EFW. Multivariate logistic regression indicated that an earlier gestational age at scanning, being the non-presenting cotwin and being the smaller cotwin were independent risk factors for sonographic EFW inaccuracy. Pregnancies in which the presenting twin was estimated to be the smaller cotwin had twice the rate of false-positive BW discordance compared with pregnancies in which the presenting twin was estimated to be the larger cotwin (36.0% vs 13.0% for BW discordance > 15%, 35.0% vs 17.0% for BW discordance > 20% and 37.7% vs 12.1% for BW discordance > 25%; all P < 0.001). The error in sonographic EFW discordance was not related to chorionicity, the position of the presenting fetus or gestational age at the time of fetal weight estimation.

CONCLUSIONS

Sonographic estimation of fetal weight within 7 days before delivery accurately predicts BW in twin pregnancy. Sonographic EFW accuracy is reduced for the non-presenting twin, the smaller cotwin and when delivery occurs at an earlier gestational age. Sonographic estimation of fetal weight discordance is less accurate when the presenting twin is the smaller cotwin. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Factors associated with large-for-gestational-age infants born after frozen embryo transfer cycles

Objective

To examine trends of frozen embryo transfer (FET) proportions and large-for-gestational-age (LGA) incidence and determine risk factors for LGA infants after FET.

Design

Retrospective cohort study.

Setting

Not applicable.

Patients

Frozen embryo transfer cycles.

Interventions

None.

Main Outcome Measures

Singleton LGA infant.

Results

The percentage of FETs increased from 20%-74% of transfers, whereas the rate of LGA among FET singleton births decreased from 18%-12% during 2004-2018. In a subanalysis of 127,525 FET-associated singleton live births during 2016-2018, patient factors associated with LGA were higher-than-normal maternal body mass index (body mass index [BMI], 25.0-29.9 kg/m²; adjusted relative risk [aRR], 1.31; 95% confidence interval [CI], 1.26-1.36; BMI, 30.0-34.9 kg/m²; aRR, 1.48; 95% CI, 1.41-1.55; and BMI, >35 Kg/m²; aRR, 1.68; 95% CI, 1.59-1.77) and ≥1 prior birth vs. none. Low maternal BMI (<18.5 vs. 18.5-24.9 kg/m²) and cycles involving patients who were non-Hispanic (NH) Asian/Native Hawaiian/Pacific Islander, NH Black, or Hispanic (compared with NH White) were at lower risk of LGA infants. Cycle factors associated with LGA included gestational carrier use (aRR, 1.25; 95% CI, 1.16-1.34) and donor sperm (aRR, 1.17; 95% CI, 1.10-1.25).

Conclusions

Although the number and proportion of FET cycles increased from 2004-2018, the rate of LGA after FET decreased. Maternal BMI, parity, and race/ethnicity were the strongest risk factors for LGA infants after FET.

Twin Growth Discordance and Risk of Postpartum Hemorrhage: A Retrospective Cohort Study

Background

In recent years, the incidence of postpartum hemorrhage has increased globally. Multiple pregnancies and cesarean sections are well-known risk factors for postpartum hemorrhage. No studies have evaluated the associations between fetal growth anomalies and postpartum hemorrhage in women with twin pregnancies undergoing cesarean section. This study aimed to identify the relationship between fetal growth anomalies and postpartum hemorrhage in women with twin pregnancies undergoing cesarean section.

Methods

This retrospective single-center study included 3,180 women with twin pregnancies at a tertiary hospital between August 2013 and July 2020. Singleton reference charts were used to assess fetal growth restriction at birth. Discordant growth was defined as an intertwin birth weight difference of ≥20%. Logistic regression analyses were used to evaluate the association between fetal growth anomalies and postpartum hemorrhage. Additionally, sensitivity analysis of abnormal placenta and stratification by twin chorionicity were conducted.

Results

The overall incidence of postpartum hemorrhage was 4.3%. Twin growth discordance, especially with fetal growth restriction, was associated with an increased risk of postpartum hemorrhage (adjusted odds ratio [AOR] = 1.62, 95% confidence interval [CI], 1.05-2.51, P = 0.031; AOR = 1.71; 95% CI, 1.08-2.70, P = 0.022; AOR = 1.98, 95% CI, 1.21-3.25, P = 0.006, respectively). After stratification, this relationship persisted in dichorionic twins (OR = 1.71, 95% CI, 1.04-2.82, P = 0.036; OR = 1.90, 95% CI, 1.13-3.21, P = 0.016; OR = 2.48, 95% CI, 1.41-4.38, P = 0.002, respectively). However, no significant association was observed in monochorionic twin pregnancies.

Conclusion

Growth discordance, especially complicated by fetal growth restriction, was associated with an increased risk of postpartum hemorrhage in women with twin pregnancies undergoing cesarean section, and was more evident in patients with dichorionic twins.

Association of Prenatal Maternal Anemia with Tics and Tourette's Syndrome in Offspring

Iron deficiency anemia (IDA) accounts for most of the anemia in pregnancy, and iron is essential for neurodevelopment. Tics and Tourette’s syndrome (TS) are neurodevelopmental disorders that manifest in childhood. A few studies reported an inconclusive association between iron deficiency and tics in children. No study has investigated the relationship between prenatal maternal anemia and tics in children. We aimed to assess the relationship between prenatal anemia exposure and the incidence of tics or TS in offspring. We linked the Taiwan National Health Insurance Research Database to the Maternal and Child Health Database for the analysis and identified 153,854 children with prenatal anemia exposure and 2,014,619 children without prenatal anemia exposure from 2004 to 2016 and followed them through 2017. Cox regression models were applied to compare the risk of tics or TS between the exposed and nonexposed groups. Among the exposed group, 37,832 were exposed at ≤12 weeks of gestational age (GA) and 116,022 at >12 weeks of GA. We observed an increased risk of tics and TS in those exposed at ≤12 weeks compared with the nonexposed group (adjusted hazard ratio (aHR) = 1.23, 95% confidence interval (CI): 1.12–1.34). The result remained consistent after adjusting for birth year, sex, birth order, maternal age, low-income levels, gestational age, birth weight, and alcohol use and smoking during pregnancy (aHR = 1.16, CI: 1.04–1.28). Fetuses exposed to maternal anemia at ≤12 weeks of GA are at high risk of tics or TS. However, this effect was attenuated to insignificance in the sibling comparison. Our study highlights the importance of detection of anemia during pregnancy and proper timing of iron supplementation.

Patterns of discordant growth and adverse neonatal outcomes in twins

BACKGROUND

Intertwin size discordance is an independent risk factor for adverse neonatal outcomes in twin pregnancies. However, size discordance at a given point in gestation fails to take into consideration information, such as the timing of onset and the rate of progression of discordance, that may be of prognostic value.

OBJECTIVE

In this study, we aimed to identify distinct patterns of discordant fetal growth in twin pregnancies and to determine whether these patterns are predictive of adverse pregnancy outcomes.

STUDY DESIGN

This was a retrospective cohort study of women with twin pregnancies in a single tertiary referral center between January 2011 and April 2020, who had at least 3 ultrasound examinations during pregnancy that included assessment of fetal biometry. Size discordance was calculated at each ultrasound examination, and pregnancies were classified into 1 of 4 predetermined patterns based on the timing of onset and the progression of discordance: pattern 1, no significant discordance group (referent); pattern 2, early (<24 weeks' gestation) progressive discordance group; pattern 3, early discordance with plateau group; or pattern 4, late (≥24 weeks' gestation) discordance group. The associations of discordance pattern (using pattern 1 as referent) with preterm birth, preeclampsia, size discordance at birth, and birthweight<10th percentile were expressed as adjusted relative risk with 95% confidence intervals and were compared with those observed for a single measurement of size discordance at 32 weeks' gestation.

RESULTS

Of 2075 women with a twin gestation who were identified during the study period, 1059 met the study criteria. Of the 1059 women, 599 (57%) were classified as no significant discordance (pattern 1), 23 (2%) as early progressive discordance (pattern 2), 160 (15%) as early discordance with plateau (pattern 3), and 277 (26%) as late discordance (pattern 4). The associations of discordance pattern with preterm birth at <34 weeks' gestation and preeclampsia were strongest for pattern 2 (rates of 43% [adjusted relative risk, 3.43; 95% confidence interval, 2.10-5.62] and 17% [adjusted relative risk, 5.81; 95% confidence interval, 2.31-14.60], respectively), intermediate for pattern 3 (rates of 23% [adjusted relative risk, 1.82; 95% confidence interval, 1.28-2.59] and 6% [adjusted relative risk, 2.08; 95% confidence interval, 1.01-4.43], respectively), and weakest for pattern 4 (rates of 12% [adjusted relative risk, 0.96; 95% confidence interval, 0.65-1.42] and 4% [adjusted relative risk, 1.41; 0.68-2.92], respectively). In contrast, a single measurement of size discordance at 32 weeks' gestation showed no association with preeclampsia and only a weak association with preterm birth at <34 weeks' gestation.

CONCLUSION

We identified 4 distinct discordance growth patterns among twins that demonstrated a dose-response relationship with adverse outcomes and seemed to be more informative than a single measurement of size discordance.

The Association between Placental Histopathology, Fetal Growth Restriction, and Preeclampsia in Twin Pregnancies

OBJECTIVE

This study aims to estimate the association between abnormal placental histopathology, fetal growth restriction (FGR), and preeclampsia (PEC) in twin pregnancies.

STUDY DESIGN

Retrospective cohort study of women with diamniotic twin pregnancies with live births at ≥24 weeks of gestation and available placental pathology. Findings were compared between women with and without FGR, which was defined as a birthweight <10th percentile, using singleton and twin growth curves, and those with and without PEC. The primary study outcome was a composite of abnormal placental histopathology. Chi-square, Fisher's exact, and Student's t-tests were used for analysis.

RESULTS

Among 859 patients with diamniotic twins, 806 (93.8%) had placental pathology. A total of 422 (52.4%) women had at least one twin with FGR, using a singleton growth curve. FGR affected 136 (16.9%) pregnancies when a twin growth curve was applied. There was no significant difference in composite outcome between groups, using either growth curve (45.5 vs. 44.8%, p = 0.84; adjusted odds ratio (aOR): 1.06, 95% CI: 0.79-1.40 and 52.2 vs. 43.7%, p = 0.07; aOR: 1.44, 95% CI: 0.90-2.10). A total of 122 of 789 (15.5%) patients developed PEC. There was no significant difference in composite outcome between patients with and without PEC (41.8 vs. 45.4%, p = 0.46; aOR: 0.79, 95% CI: 0.53-1.18).

CONCLUSION

In twin pregnancies, FGR and PEC are not associated with abnormal placental histopathology. This suggests that the pathologic placental manifestations of these conditions may differ in twins and include factors other than those commonly described in singletons.

The Association between Gestational Weight Gain in Each Trimester and Pregnancy Outcomes in Twin Pregnancies

OBJECTIVE

Adequate maternal weight gain in twin pregnancies is associated with improved outcomes such as increased fetal growth and decreased incidence of preterm birth. However, it remains unclear when gestational weight gain has the greatest influence on pregnancy outcomes. Our objective was to identify at which time in a twin pregnancy does inadequate maternal weight gain have the greatest association with adverse pregnancy outcomes.

STUDY DESIGN

This is a retrospective cohort study of women with twin pregnancies and normal prepregnancy body mass index (BMI, 18.5-24.9 kg/m²) who delivered at ≥24 weeks' gestation by a single maternal-fetal medicine practice between 2005 and 2017. Baseline characteristics and pregnancy outcomes were compared between women with and without adequate average gestational weight gain (weight gain per week based on the 2009 Institute of Medicine recommendations). This analysis was performed for weight gain over the entire pregnancy, as well as from 0 to 16, 16 to 24, and 24 weeks to delivery. Multivariable regression analysis was performed to control for potential confounding variables.

RESULTS

A total of 609 women with twin pregnancies and normal prepregnancy BMI were included, of whom 386 (63.4%) had adequate average gestational weight gain over the entire pregnancy and 223 (36.6%) did not. Inadequate average gestational weight gain between 0 and 16 weeks' gestation was associated with a higher incidence of birthweight less than the 10th percentile for gestational age (adjusted odds ratio [aOR]: 1.67; 95% confidence interval [CI]: 1.11-2.51) and less than the 5th percentile for gestational age (aOR: 2.10; 95% CI: 1.29-3.40). Inadequate gestational weight gain between 16 and 24 weeks was associated with lower birthweight of the larger twin (β: -0.09; p = 0.04). Inadequate weight gain from 24 weeks to delivery was associated with spontaneous preterm birth <37 weeks' gestation (aOR: 1.67; 95% CI: 1.13-2.47), <34 weeks' gestation (aOR: 4.32; 95% CI: 2.45-7.63), <32 weeks' gestation (aOR: 9.07; 95% CI: 3.66-22.48), and a lower incidence of preeclampsia (aOR: 0.31; 95% CI: 0.16-0.63).

CONCLUSION

In twin pregnancies, gestational weight gain between 0 and 16 weeks as well as between 16 and 24 weeks is most associated with fetal growth, whereas gestational weight gain after 24 weeks is most associated with preterm birth. This may help elucidate the mechanism of action of the impact of gestational weight gain in twin pregnancies.

Pathologic Basis for the Definition of Discordant Growth in Dichorionic Twins

OBJECTIVE

The aim of the current study was to identify the optimal cutoff that should define discordance in dichorionic twin gestations through correlation with abnormal placental pathology as a specific measure of fetal growth restriction of the smaller twin.

METHODS

We performed a retrospective cohort study of all women with dichorionic twin pregnancies who gave birth in a single center between 2002 and 2015. We investigated the association between the level of growth discordance and maternal vascular malperfusion (MVM) pathology in the placenta of the smaller twin, with and without adjustment for whether the smaller twin is small for gestational age (SGA).

RESULTS

A total of 1,198 women with dichorionic twin gestation met the study criteria. The rate of MVM pathology in the placenta of the smaller twin increased with the level of discordance and was most obvious for discordance ≥25% (rate of MVM 12.0% compared with 2.8% in cases with discordance <10%, adjusted relative risk [aRR] 3.71, 95% confidence interval [CI] 1.97-6.99). When the analysis was adjusted for SGA of the smaller twin, discordance was independently associated with MVM pathology only when growth discordance was ≥25% (aRR 2.18, 95%-CI 1.01-4.93), while SGA was strongly associated with MVM pathology irrespective of the level of discordance.

CONCLUSION

Our findings suggest that discordant growth in dichorionic twins should raise the concern of fetal growth restriction of the smaller twin, irrespective of whether the smaller twin is SGA, only when the discordance s ≥25%. The association of lower levels of discordance with abnormal placental pathology is mainly driven by the confounding effect of SGA of the smaller twin.

Twin Pregnancies, Crown-rump Length and Birthweight Discordancy: The Influence of Chorionicity

OBJECTIVE

 The purpose of the present study was to analyze the influence of chorionicity in the biometric parameters crown-rump length (CRL), birthweight (BW), crown-rump length discordancy (CRLD) and birthweight discordancy (BWD), determine the correlation between these latter two in cases of intertwin discordancy, and to analyze the influence of chronicity in the presence of these discordancies with clinical relevance (> 10% and > 15%, respectively).

METHODS

 The present study was a retrospective study based on the twin pregnancy database of the Centro Hospitalar S. João (2010-2015), including 486 fetuses among 66 monochorionic (MC) and 177 dichorionic gestations (DC). The inclusion criteria were multiple pregnancies with 2 fetuses and healthy twin gestations. The exclusion criteria were trichorionic gestations and pregnancies with inconclusive chorionicity, multiple pregnancy with ≥ 3 fetuses and pathological twin gestations.

RESULTS

 No statistically significant difference was found in BW (p = 0.09) and in its discordancy (p = 0.06) nor in CRL (p = 0.48) and its discordancy (p = 0.74) between MCs and DCs. Crown-rump length discordancy and birthweight discordancy were correlated by the regression line "BWD = 0.8864 x CRLD + 0.0743," with r²  = 0.1599. Crown-rump length discordancy > 10% was found in 7.58% of monochorionic and in 13.56% of dichorionic twins. Birthweight discordancy > 15% was detected in 16.67% of monochorionic and in 31.64% of dichorionic twins.

CONCLUSION

 No statistically significant influence of chorionicity was identified in both birthweight and birthweight discordancy, as in crown-rump length and crown-rump length discordancy. Birthweight discordancy was correlated to crown-rump length discordancy in 20% of cases.

Weight gain and pregnancy outcomes in overweight or obese women with twin gestations

BACKGROUND

While adequate weight gain in twin pregnancies with normal prepregnancy BMI has been associated with improved pregnancy outcomes, it remains unclear whether adequate weight gain in patients with overweight or obese prepregnancy BMI is associated with similarly improved pregnancy outcomes, and whether this comes at the expense of maternal health risks such as increased risk for gestational diabetes or hypertension.

OBJECTIVE

To estimate the association between adherence to weight gain recommendations and pregnancy outcomes in overweight and obese women with twin pregnancies.

METHODS

This is a retrospective cohort study of women with overweight (BMI 25.0-29.9 kg/m²) and obese prepregnancy BMI (≥30.0 kg/m²) and twin pregnancies delivered >24 weeks by a single MFM practice between 2005 and 2017. Baseline characteristics, weight gain patterns, and pregnancy outcomes were compared between women who met or exceeded, and who did not meet gestational weight gain requirements, as recommended by the Institute of Medicine (IOM) in 2009. Since total weight gain is also dependent on gestational age at delivery, we used weight gain per week to define adequate weight gain for overweight (0.85 lb/week) and obese (0.68 lb/week) women.

RESULTS

A total of 252 overweight and obese women with twin pregnancies met inclusion criteria, 171 (67.9%) of whom met or exceeded weight gain requirements and 81 (32.1%) of whom did not. There were no differences in baseline clinical and demographic characteristics between the two groups. Women with inadequate weight gain had significantly less weight gain in each trimester, as well as less total weight gain for the whole pregnancy. Women with inadequate average gestational weight gain had significantly lower birthweights of the larger twin (2440 versus 2675 g, p = .001) and the smaller twin (2212 versus 2398 g, p = .005), higher incidence of spontaneous preterm birth <37 weeks (33.3 versus 21.1%, p = .03), higher incidence of premature rupture of membranes (24.7 versus 11.7%, p = .008), and greater likelihood of any twin birthweight < 10th percentile for gestational age (51.9 versus 35.5%, p = .01). There were no differences in the likelihood of cesarean delivery, preeclampsia, or gestational diabetes between the two groups. These results did not differ after excluding the 24 women in the cohort with excessive weight gain.

CONCLUSIONS

For overweight and obese women with twin gestations, meeting the IOM recommendations for weight gain in pregnancy is associated with improved pregnancy outcomes. CondensationWomen with overweight or obese prepregnancy BMI in twin gestations who gain the recommended amount of weight in pregnancy have improved pregnancy outcomes.

[Noninvasive prenatal screening for twin pregnancy: an analysis of 2057 cases]

OBJECTIVE

To analyze the results of noninvasive prenatal screening (NIPS) for fetal chromosome aneuploidy in twin pregnancy.

METHODS

A total of 2057 women with twin-pregnancy between 12-26⁺⁶ weeks were recruited from Women's Hospital, Zhejiang University School of Medicine, Hangzhou Municipal Women's Hospital and Jiaxing Maternal and Child Health Hospital during February 2015 to August 2018. The cell-free DNA was extracted from the peripheral blood sample for DNA library, and non-invasive prenatal testing (NIPT) was performed by high-throughput sequencing technique. The fetal karyotype analysis or neonatal karyotype analysis was performed in pregnant women with fetal chromosome aneuploidy, and all subjects were followed up. The efficiency of NIPS testing for twin aneuploidy was calculated.

RESULTS

NIPS revealed chromosome abnormalities in 11 out of 2057 twin pregnant women, 9 cases were confirmed chromosome abnormalities, 2 cases were normal and no false negative cases. In this screening, the detection rate, sensitivity, specificity, positive predictive value, false positive rate of NIPS were 100.00%, 100.00%, 99.90%, 81.82%, 0.10%. Those were 100.00%, 100.00%, 99.95%, 87.50% and 0.05% for trisomy 21, 100.00%, 100.00%, 100.00%, 100.00%, 0.00% for trisomy18, and the specificity and false positive rate for trisomy13 were 99.95% and 0.05%, respectively.

CONCLUSIONS

NIPS can detect fetal chromosomal aneuploidy rapidly and accurately in twin pregnancies,and it is of value in clinical application.

Placental T2* estimated by magnetic resonance imaging and fetal weight estimated by ultrasound in the prediction of birthweight differences in dichorionic twin pairs

INTRODUCTION

Intertwin birthweight (BW) difference is associated with an increased risk of adverse outcome. Ultrasound estimated fetal weight (EFW) is the current method to predict intertwin BW difference, however, the sensitivity is poor. Therefore, new methods are needed. Placental T2* estimated by magnetic resonance imaging (MRI) provides non-invasive information about the placental function. This study aimed to investigate placental T2* difference as a new predictor of BW difference, and to compare it to the EFW.

METHODS

We included 25 dichorionic twin pairs at 19-38 weeks' gestation. Placental T2* was obtained by MRI and EFW by ultrasound. Correlations between each predictor and BW difference were examined by simple linear regression, and the combined model was analyzed by multiple linear regression and likelihood ratio test.

RESULTS

Strong positive correlations were demonstrated between intertwin differences in placental T2* and BW (r = 0.80, p < 0.005), and EFW and BW (r = 0.64, p < 0.005). Placental T2* difference was a strong independent predictor of BW difference (p < 0.001), and the combined model performed better than each predictor alone (p < 0.0001).

DISCUSSION

This pilot study demonstrates that placental T2* difference may be a predictor of intertwin BW difference irrespectively of fetal size. The clinical potential of this method deserves further investigation in a larger clinical study.

Weight gain and pregnancy outcomes in underweight women with twin gestations

Background: Adherence to minimum weight gain recommendations in twin pregnancies as defined by the Institute of Medicine (IOM) guidelines is associated with improved pregnancy outcomes; however, these recommendations have yet to be made for underweight women (BMI < 18.5 kg/m²).Objective: To determine if existing pregnancy weight gain recommendations in twin gestations apply to women with underweight prepregnancy body mass index (BMI), and if these women have similar pregnancy outcomes to women with normal prepregnancy BMI.Methods: This is a retrospective cohort study of women with underweight (BMI < 18.5 kg/m²) and normal prepregnancy BMI (18.5-24.9 kg/m²) and twin pregnancies delivered > 24 weeks by a single Maternal Fetal Medicine (MFM) practice between 2005-2017. Weight gain patterns and pregnancy outcomes were compared between women with underweight prepregnancy BMI and normal prepregnancy BMI. The primary outcomes of the study were gestational age at delivery and intrauterine growth restriction.Results: A total of 664 women met inclusion criteria during the study period, 55 (8.3%) of whom had an underweight prepregnancy BMI, and 609 (91.7%) of whom had a normal prepregnancy BMI. There were no differences in baseline clinical and demographic characteristics between the groups, nor any differences in overall weight gain or weight gain patterns between the two groups. There were no significant differences between the groups in birthweight of the larger twin (2415 versus 2489 g, p = .26) or the smaller twin (2150 versus 2190 g, p = .55), gestational age at delivery (35.8 versus 35.8 weeks, p = .96), incidence of preterm birth < 34 weeks (16.4 versus 16.3%, p = .98), spontaneous preterm birth < 34 weeks (9.1 versus 11.7%, p = .57), or the incidence of either twin with a birthweight < 10% for gestational age (60.0 versus 56.0%, p = .57) or < 5% for gestational age (36.4 versus 30.9%, p = .40).Conclusions: Women with underweight prepregnancy BMI who gain equal weight to women with normal prepregnancy BMI have similar pregnancy outcomes. The recommendations for adequate weight gain in women with underweight prepregnancy BMI should therefore not exceed those for women with normal prepregnancy BMI.

Metabolomic signatures of low birthweight: Pathways to insulin resistance and oxidative stress

Several studies suggest that low birthweight resulting from restricted intrauterine growth can leave a metabolic footprint which may persist into adulthood. To investigate this, we performed metabolomic profiling on 5036 female twins, aged 18-80, with weight at birth information available from the TwinsUK cohort and performed independent replication in two additional cohorts. Out of 422 compounds tested, 25 metabolites associated with birthweight in these twins, replicated in 1951 men and women from the Hertfordshire Cohort Study (HCS, aged 66) and in 2391 men and women from the North Finland Birth 1986 cohort (NFBC, aged 16). We found distinct heterogeneity between sexes and, after adjusting for multiple tests and heterogeneity, two metabolites were reproducible overall (propionylcarnitine and 3-4-hydroxyphenyllactate). Testing women only, we found other metabolites associated with lower birthweight from the meta-analysis of the three cohorts (2-hydroxy-butyric acid and γ-glutamylleucine). Higher levels of all these metabolites can be linked to insulin resistance, oxidative stress or a dysfunction of energy metabolism, suggesting that low birthweight in both twins and singletons are having an impact on these pathways in adulthood.

Prenatal prediction of significant intertwin birthweight discordance using standard second and third trimester sonographic parameters

INTRODUCTION

Our study aim was to evaluate standard ultrasound-derived fetal biometric parameters in the prediction of clinically significant intertwin birthweight discordance defined as ≥18%.

MATERIAL AND METHODS

This was a secondary analysis of a prospective cohort study of 1028 unselected twin pairs recruited over a two-year period. Dichorionic twins underwent two-weekly ultrasonographic surveillance from 24 weeks' gestation, with surveillance of monochorionic twins two-weekly from 16 weeks. Ultrasonographic biometric data from 24 to 36 weeks were evaluated for the prediction of an intertwin birthweight discordance threshold ≥18%. Umbilical artery Doppler waveform data was also analyzed to evaluate whether it was predictive of birthweight discordance.

RESULTS

Of the 956 twin pairs analyzed for discordance, 208 pairs were found to have a clinically significant birthweight discordance ≥18%. All biometric parameters were predictive of significant inter-twin birthweight discordance at low cut-offs, with low discriminatory powers when ROC curves were analyzed. Discordance in estimated fetal weight was predictive of a significant birthweight discordance at all gestational categories with cut-offs between 8 and 11%. A low-discriminatory power and poor sensitivity and specificity were also observed. An abnormal umbilical artery Doppler was predictive of birthweight discordance ≥18% between 28 and 32 weeks' gestation, although with poor sensitivity and specificity.

CONCLUSIONS

Calculation of estimated fetal weight and birthweight discordance between twins allows minimal margin for error. These margins make it difficult to accurately predict those who are at or above the discordance threshold of 18%. These findings highlight that small intertwin discrepancies in weight and biometry should not be overlooked and merit further investigation.

Effects of Intrauterine Environment on the Magnitude of Differences Within the Pairs of Monozygotic and Dizygotic Twins

The aim of this study was to determine the effects of intrauterine environment on the magnitude of intrapair differences in six somatic traits of monozygotic (MZ) and dizygotic (DZ) twins (1,263 pairs; 424 MZ twins and 839 DZ twins). Differences in intrauterine environments of MZ twins enforced division of the research material into four groups: (1) MZ-MC-TTTS - MZ twins from monochorionic (MC) pregnancies with twin-to-twin transfusion syndrome (TTTS), (2) MZ-MC (without TTTS)-MZ twins from MC pregnancies without TTTS, (3) MZ-DC-MZ twins from dichorionic (DC) pregnancies, and (4) DZ-DZ twins. The intrapair differences in all analyzed somatic traits, especially body weight and circumference of the chest, were the largest in the case of MZ twins from MC pregnancies with TTTS. DZ twins were the group presenting with the second largest intrapair differences in the analyzed traits. At the end of pregnancy, that is, in lunar months 9 and 10, the magnitude of intrapair differences in all traits of twins from this group was significantly greater than in MZ twins from both MC and DC pregnancies. Irrespective of the analyzed period, the least evident, statistically insignificant intrapair differences in the studied traits were documented in the case of MZ twins from MC pregnancies without TTTS and twins from DC pregnancies. These findings imply that the differentiating effect of intrauterine environment is associated with the occurrence of TTTS, rather than with chorionicity, as postulated previously.

Breastfeeding and Growth of Children in the Peri/postnatal Epigenetic Twins Study (PETS): Theoretical Epigenetic Mechanisms

BACKGROUND

The prevalence of overweight infants and toddlers has increased by 60% in the past 30 years and is a significant contributor to diabetes, cardiovascular disease, and early morbidity and mortality. The World Health Organization's updated meta-analysis in 2013 observed an association between breastfeeding and a lower prevalence of obesity later in life. The purpose of this study was to assess the growth of children in a cohort of Australian twins to examine associations between duration of breastfeeding and growth at 18 months of age. Our hypothesis is that the anthropometric measurements of the participants will be greater with shorter duration of breastfeeding.

METHODS

Methods include using cross-sectional data from a cohort at the 18-month visit (n = 179) in the Peri/postnatal Epigenetics Twins Study (PETS) to assess the relationship between duration of breastfeeding and infant size at 18 months of age. Inclusion criteria were birth weight of more than 2000 grams and breastfed for less than 1 month, 1 to 3 months, or 4 to 6 months.

RESULTS

The analysis suggested that infants breastfed for 1 to 3 months were significantly larger than infants breastfed for 4 to 6 months in terms of mean body mass index (BMI) (0.61 kg/m(2); P = .02; 95% confidence interval [CI], 0.17-1.05), arm circumference (0.66 cm; P = .006; 95% CI, 0.26-1.06), and abdominal circumference (1.16 cm; P = .03; 95% CI, 0.26-2.06). The analysis also suggested that infants breastfed for less than 1 month were significantly larger than infants breastfed for 4 to 6 months in terms of mean arm circumference (0.72 cm; P = .009; 95% CI, 0.26-1.17).

CONCLUSION

Results suggest that supplementing with non-breast milk before 4 months of age was associated with an increased BMI, arm circumference, and abdominal circumference at 18 months of age. The mean BMI decreased from 85% to 65% when infants were breastfeeding for 4 to 6 months as compared to breastfeeding for 1 to 3 months. Breastfeeding for 4 to 6 months appeared to protect against the risk of obesity for the children in the PETS.

The Prenatal Environment in Twin Studies: A Review on Chorionicity

A literature search was conducted to identify articles examining the association of chorionicity (e.g., whether twins share a single chorion and thus placenta or have separate chorions/placentas) and genetics, psychiatry/behavior, and neurological manifestations in humans twins and higher-order multiples. The main aim was to assess how frequently chorionicity has been examined in relation to heritability estimates, and to assess which phenotypes may be most sensitive to, or affected by, bias in heritability estimates because of chorionicity. Consistent with the theory that some chorionicity effects could lead to overestimation and others to underestimation of heritability, there were instances of each across the many phenotypes reviewed. However, firm conclusions should not be drawn since some of the outcomes were only examined in one or few studies and often sample sizes were small. While the evidence for bias due to chorionicity was mixed or null for many outcomes, results do, however, consistently suggest that heritability estimates are underestimated for measures of birth weight and early growth when chorionicity is not taken into account.

The association between maternal height and pregnancy outcomes in twin gestations

OBJECTIVE

We sought to assess the association between maternal height and the risk of preterm birth, fetal growth restriction and mode of delivery in twin gestations.

STUDY DESIGN

Cohort study of patients with twin pregnancies delivered from 2005 to 2014. We compared pregnancy outcomes between patients of short stature ≤159 cm to those of normal stature ≥160 cm. Patients with monoamniotic twins and major fetal anomalies were excluded. Pearson's correlation, Chi-square and Student's t-test were used as appropriate.

RESULTS

Six hundred and sixty-six patients were included, 159 (23.9%) of whom had short stature (mean height 155.8 ± 2.5 cm) and 507 (76.1%) of whom had normal stature (mean height 167.2 ± 5.5 cm). There were no differences in outcomes between the groups in regards to preterm birth, gestational age (GA) at delivery, birth weight of either twin, preeclampsia, gestational diabetes or cesarean section rate. Results were similar when the groups were stratified by parity. As a continuous variable, maternal height did not correlate with GA at delivery (p= 0.388), cesarean delivery (p = 0.522) nor the birth weight of the larger (p = 0.206) or smaller (p = 0.307) twin.

CONCLUSION

In twin pregnancies, maternal short stature is not associated with preterm birth, fetal growth restriction or cesarean section rate. This suggests that although anthropometric measurements have long been used to counsel patients in regards to outcomes, patients of short stature should be reassured that their height does not appear to lead to adverse twin pregnancy outcomes.

DNA Methylation Changes in the IGF1R Gene in Birth Weight Discordant Adult Monozygotic Twins

Low birth weight (LBW) can have an impact on health outcomes in later life, especially in relation to pre-disposition to metabolic disease. Several studies suggest that LBW resulting from restricted intrauterine growth leaves a footprint on DNA methylation in utero, and this influence likely persists into adulthood. To investigate this further, we performed epigenome-wide association analyses of blood DNA methylation using Infinium HumanMethylation450 BeadChip profiles in 71 adult monozygotic (MZ) twin pairs who were extremely discordant for birth weight. A signal mapping to the IGF1R gene (cg12562232, p = 2.62 × 10−8), was significantly associated with birth weight discordance at a genome-wide false-discovery rate (FDR) of 0.05. We pursued replication in three additional independent datasets of birth weight discordant MZ pairs and observed the same direction of association, but the results were not significant. However, a meta-analysis across the four independent samples, in total 216 birth-weight discordant MZ twin pairs, showed a significant positive association between birth weight and DNA methylation differences at IGF1R (random-effects meta-analysis p = .04), and the effect was particularly pronounced in older twins (random-effects meta-analysis p = .008, 98 older birth-weight discordant MZ twin pairs). The results suggest that severe intra-uterine growth differences (birth weight discordance >20%) are associated with methylation changes in the IGF1R gene in adulthood, independent of genetic effects.

Preterm birth or small for gestational age in a singleton pregnancy and risk of recurrence in a subsequent twin pregnancy

OBJECTIVE

To evaluate whether a history of preterm birth or small for gestational age (SGA) in a singleton pregnancy is associated with an increased risk of recurrence of the same condition in a subsequent twin pregnancy.

METHODS

Retrospective cohort study of twin pregnancies delivered in one maternal-fetal medicine practice from 2005 to 2014. Patients with a history of singleton preterm birth at less than 37 weeks of gestation were compared with patients with a history of singleton term birth and nulliparous patients. A similar analysis was performed for a history of SGA (birth weight less than 10%).

RESULTS

Six hundred forty-seven twin pregnancies were included. The prior singleton gestational age at delivery was significantly positively correlated with the twin gestational age at delivery (P<.001), and the prior singleton birth weight was significantly positively correlated with the birth weight of the larger twin (P<.001) and the smaller twin (P<.001). The rate of twin preterm birth before 32 weeks of gestation was 3.5% in patients with a prior term birth, 9.2% in nulliparous patients, and 26% in patients with a prior preterm birth (P<.001). The rate of SGA in patients with a prior birth not complicated by SGA was 42.1%, in nulliparous women it was 54.4%, and in patients with a history of SGA it was 65.2% (P=.007). On regression analysis, prior preterm birth and SGA of a singleton pregnancy were independently associated with recurrence of the same condition in a subsequent twin pregnancy.

CONCLUSION

Prior preterm birth and SGA in a singleton pregnancy increase the risk of the same condition in a subsequent twin pregnancy. We postulate that the extrinsic mechanism responsible for the pathophysiology of adverse outcomes in twin pregnancies overlaps with that in singleton pregnancies.

The relationship between preeclampsia and intrauterine growth restriction in twin pregnancies

OBJECTIVE

Preeclampsia and intrauterine growth restriction (IUGR) are correlated in singleton pregnancies. The objective of this study was to estimate their relationship in twin pregnancies.

STUDY DESIGN

Cohort of 578 patients with twin pregnancies delivered by 1 maternal fetal medicine practice from 2005-2013. Patients with chronic hypertension, monochorionic-monoamniotic placentation, twin-twin transfusion, and major congenital anomalies were excluded. Standard definitions were used for gestational hypertension and preeclampsia. We defined IUGR as any twin birthweight less than the 5th percentile for gestational age, as well as any twin birthweight less than the 10th percentile for gestational age.

RESULTS

The incidence of preeclampsia was 14.9%, the incidence of birthweight <10% was 50.0%, and the incidence of birthweight <5% was 27.5%. Comparing patients with and without preeclampsia, the rate of birthweight <5th percentile did not differ (27.9% vs 27.4%, P = .929), nor did the rate of birthweight <10th percentile (48.8% vs 50.2%, P = .815). We had 80% power with an alpha error of 5% to show a difference in the likelihood of IUGR <10th percentile from 50% to 66% and a difference in the likelihood of IUGR <5th percentile from 27% to 42% in patients without and with preeclampsia.

CONCLUSION

In patients with twin pregnancy, there is no correlation between preeclampsia and IUGR. This suggests that in twin pregnancies, as opposed to singleton pregnancies, the pathophysiology may differ between these 2 common conditions.

Degree and rate of growth discordance in dichorionic twins conceived by in vitro fertilization

Objective. Our objective was to estimate degree and rate of discordant growth and its impact on perinatal outcome in dichorionic twin pregnancies conceived by in vitro fertilization (IVF) compared to those conceived spontaneously. Study Design. Growth discordance was defined as 90th percentiles for the study population. Adverse perinatal outcome was defined as 5-minute Apgar score <7 and/or admission to neonatal intensive care unit. Results. In the total study population of dichorionic twins (176 conceived by IVF and 215 spontaneously), 30% discordant growth represented the 90th percentile. After adjusting for gestational age, discordant twins conceived by IVF or spontaneously were at higher risk for adverse perinatal outcome (hazard ratio 4.4; 95% CI 2.4-8.3, P < 0.0001; hazard ratio 2.5; 95% CI 1.5-4.4, P = 0.001, resp.). Similar rates of 5-minute Apgar score <7, admission to neonatal intensive care unit, and delivery <34 weeks were found between discordant twins conceived by IVF and those conceived spontaneously. Conclusion. Dichorionic twins conceived by IVF are at similar risk for the rate and degree of discordant growth and adverse perinatal outcome compared to dichorionic twins conceived spontaneously.

Variants Close to NTRK2 Gene Are Associated With Birth Weight in Female Twins

Low weight at birth has previously been shown to be associated with a number of adult diseases such as type 2 diabetes, cardiovascular disease, high blood pressure, and obesity later in life. Genome-wide association studies (GWAS) have been published for singleton-born individuals, but the role of genetic variation in birth weight (BW) in twins has not yet been fully investigated. A GWAS was performed in 4,593 female study participants with BW data available from the TwinsUK cohort. A genome-wide significant signal was found in chromosome 9, close to the NTRK2 gene (OMIM: 600456). QIMR, an Australian twin cohort (n = 3,003), and UK-based singleton-birth individuals from the Hertfordshire cohort (n = 2,997) were used as replication for the top two single nucleotide polymorphism (SNPs) underpinning this signal, rs12340987 and rs7849941. The top SNP, rs12340987, was found to be in the same direction in the Australian twins and in the singleton-born females (fixed effects meta-analysis beta = -0.13, SE = 0.02, and p = 1.48 × 10−8) but not in the singleton-born males tested. These findings provide an important insight into the genetic component of BW in twins who are normally excluded due to their lower BW when compared with singleton births, as well as the difference in BW between twins. The NTRK2 gene identified in this study has previously been associated with obesity.

Significance of growth discordance in appropriately grown twins

OBJECTIVE

We sought to determine the perinatal risks associated with growth discordance in appropriately grown twin gestations.

STUDY DESIGN

We conducted a retrospective cohort study of all twin gestations excluding those complicated by monoamnionicity, twin-twin transfusion syndrome, structural anomalies, selective reduction, or a birthweight <10th percentile. Growth discordance was defined as ≥20%. Outcomes considered were stillbirth, preterm delivery <34 weeks and <28 weeks, and admission to the neonatal intensive care unit. Analyses were stratified by chorionicity.

RESULTS

Of 895 included dichorionic pregnancies, 63 (7.0%) were discordant. Discordant dichorionic twins were not at increased risk of preterm delivery <34 weeks (34.9% vs 25.6%; relative risk [RR], 1.4; 95% confidence interval [CI], 1.0-1.9), preterm delivery <28 weeks (3.2% vs 2.8%; RR, 1.1; 95% CI, 0.3-4.8), or admission to intensive care (26.9% vs 23.5%; RR, 1.5; 95% CI, 1.0-2.3). We had >90% power to detect a 2.5-fold increase in preterm delivery and admission to the neonatal intensive care unit in dichorionic twins. Of 250 monochorionic pregnancies, 23 (9.2%) were discordant. Monochorionic twin pregnancies were at increased risk of preterm delivery <34 weeks (65.2% vs 26.4%; RR, 2.5; 95% CI, 1.7-3.6), preterm delivery <28 weeks (34.8% vs 4.0%; RR, 8.8; 95% CI, 3.7-20.5), and admission to intensive care (68.2% vs 23.3%; RR, 2.9; 95% CI, 2.0-4.3).

CONCLUSION

In appropriately grown twins, growth discordance is a risk factor for adverse perinatal outcomes in monochorionic, but not dichorionic, twins. Discordant monochorionic twins may benefit from increased antenatal surveillance.

Placental pathology, birthweight discordance, and growth restriction in twin pregnancy: results of the ESPRiT Study

OBJECTIVE

We sought to evaluate the association between placental histological abnormalities and birthweight discordance and growth restriction in twin pregnancies.

STUDY DESIGN

We performed a multicenter, prospective study of twin pregnancies. Placentas were examined for evidence of infarction, retroplacental hemorrhage, chorangioma, subchorial fibrin, or abnormal villus maturation. Association of placental lesions with chorionicity, birthweight discordance, and growth restriction were assessed.

RESULTS

In all, 668 twin pairs were studied, 21.1% monochorionic and 78.9% dichorionic. Histological abnormalities were more frequent in placentas of smaller twins of birthweight discordant pairs (P = .02) and in placentas of small for gestational age infants (P = .0001) when compared to controls. The association of placental abnormalities with both birthweight discordance and small for gestational age was significant for dichorionic twins (P = .01 and .0001, respectively). No such association was seen in monochorionic twins.

CONCLUSION

In a large, prospective, multicenter study, we observed a strong relationship between abnormalities of placental histology and birthweight discordance and growth restriction in dichorionic, but not monochorionic, twin pregnancies.

Extrinsic factors influencing fetal deformations and intrauterine growth restriction

The causes of intrauterine growth restriction (IUGR) are multifactorial with both intrinsic and extrinsic influences. While many studies focus on the intrinsic pathological causes, the possible long-term consequences resulting from extrinsic intrauterine physiological constraints merit additional consideration and further investigation. Infants with IUGR can exhibit early symmetric or late asymmetric growth abnormality patterns depending on the fetal stage of development, of which the latter is most common occurring in 70-80% of growth-restricted infants. Deformation is the consequence of extrinsic biomechanical factors interfering with normal growth, functioning, or positioning of the fetus in utero, typically arising during late gestation. Biomechanical forces play a critical role in the normal morphogenesis of most tissues. The magnitude and direction of force impact the form of the developing fetus, with a specific tissue response depending on its pliability and stage of development. Major uterine constraining factors include primigravida, small maternal size, uterine malformation, uterine fibromata, early pelvic engagement of the fetal head, aberrant fetal position, oligohydramnios, and multifetal gestation. Corrective mechanical forces similar to those that gave rise to the deformation to reshape the deformed structures are often used and should take advantage of the rapid postnatal growth to correct form.

Insulin requirements in type 1 diabetic pregnancy: do twin pregnant women require twice as much insulin as singleton pregnant women?

OBJECTIVE

To evaluate the insulin requirements in women with type 1 diabetes during twin pregnancy compared with singleton pregnancy.

RESEARCH DESIGN AND METHODS

At 8, 14, 21, 27, and 33 gestational weeks, insulin requirements and HbA(1c) were compared between 15 twin pregnant women from 2000 to 2011 and 108 singleton pregnant women from 2004 to 2006.

RESULTS

In twin pregnancies, the weekly increase in daily insulin dose between 14 and 27 weeks was higher than in singleton pregnancies (median 3.0 international units [IU] [range 0.9-4.9] versus 1.5 IU [-1.5 to 5.9]; P = 0.008) and remained stable from 27 to 33 weeks. The increment in total insulin requirement from before pregnancy until 33 weeks tended to be higher in twin pregnancies (103% [36-257%] versus 71% [-20 to 276%]; P = 0.07). Throughout pregnancy, HbA(1c) was similar in twin and singleton pregnancies.

CONCLUSIONS

In twin pregnancies, the weekly increase in insulin dose between 14 and 27 weeks was doubled compared with singleton pregnancies.

Autism risk in small- and large-for-gestational-age infants

OBJECTIVE

We sought to determine whether small-for-gestational age (SGA) and large-for-gestational age (LGA) birthweights increase autism risk.

STUDY DESIGN

This was a retrospective cohort analysis comparing children with autism (n = 20,206) within a birth cohort (n = 5,979,605). Stratification by sex and birthweight percentile (SGA, <5th or 5-10th percentile; appropriate size for gestational age [GA], >10th to <90th percentile; LGA, either 90-95th or >95th percentile) preceded Cochran-Mantel-Haenszel analysis for GA effect, and multivariate analysis.

RESULTS

Autism risk was increased in preterm SGA (<5th percentile) infants 23-31 weeks (adjusted odds ratio [aOR], 1.60; 95% confidence interval [CI], 1.09-2.35) and 32-33 weeks (aOR, 1.83; 95% CI, 1.16-2.87), and term LGA (>95th percentile) infants 39-41 weeks (aOR, 1.16; 95% CI, 1.08-1.26), but was decreased in preterm LGA infants 23-31 weeks (aOR, 0.45; 95% CI, 0.21-0.95).

CONCLUSION

SGA was associated with autism in preterm infants, while LGA demonstrated dichotomous risk by GA, with increased risk at term, and decreased risk in the premature infants. These findings likely reflect disparate pathophysiologies, and should influence prenatal counseling, pediatric autism screening, and further autism research.

Placental cord insertion and birthweight discordance in twin pregnancies: results of the national prospective ESPRiT Study

OBJECTIVE

The purpose of this study was to evaluate the impact of noncentral placental cord insertion on birthweight discordance in twins.

STUDY DESIGN

We performed a multicenter, prospective trial of twin pregnancies. Placental cord insertion was documented as central, marginal, or velamentous according to a defined protocol. Association of the placental cord insertion site with chorionicity, birthweight discordance, and growth restriction were assessed.

RESULTS

Eight hundred sixteen twin pairs were evaluated; 165 pairs were monochorionic, and 651 pairs were dichorionic. Monochorionic twins had higher rates of marginal (P = .0068) and velamentous (P < .0001) placental cord insertion. Noncentral placental cord insertion was more frequent in smaller twins of discordant pairs than control pairs (29.8% vs 19.1%; P = .004). Velamentous placental cord insertion in monochorionic twins was associated significantly with birthweight discordance (odds ratio, 3.5; 95% confidence interval, 1.3-9.4) and growth restriction (odds ratio, 4; 95% confidence interval, 1.1-14.3).

CONCLUSION

Noncentral placental cord insertion contributes to birthweight discordance in monochorionic twin pregnancies. Sonographic delineation of placental cord insertion may be of value in antenatal assessment of twin pregnancies.

Second-trimester estimated fetal weight and discordance in twin pregnancies: association with fetal growth restriction

OBJECTIVES

The purpose of this study was to estimate the association between second-trimester estimated fetal weight and fetal growth restriction in twin pregnancies.

METHODS

A historical cohort of 306 twin pregnancies from a single center was analyzed. Estimated fetal weight and discordance at 18 to 24 weeks were calculated. Patients with a fetus whose second-trimester estimated fetal weight was below the 10th percentile were compared to patients with both fetuses at or above the 10th percentile. Also, patients with second-trimester discordance of 15% or greater were compared to patients with discordance of less than 15%.

RESULTS

Second-trimester discordance was significantly smaller than birth weight discordance (mean discordance ± SD, 7.41% ± 6.06% versus 11.43% ± 9.6%, respectively; P < .001). Patients with second-trimester discordance of 15% or greater were significantly more likely to deliver a twin with a birth weight below the 10th percentile for gestational age (67.7% versus 44.1%; P = .012) and below the 5th percentile for gestational age (41.9% versus 22.8%; P = .019). Patients with a second-trimester estimated fetal weight below the 10th percentile were significantly more likely to deliver a twin with a birth weight below the 10th percentile for gestational age (65.5% versus 44.5%; P = .031) and below the 5th percentile for gestational age (55.2% versus 21.5%; P < .001).

CONCLUSIONS

In twin pregnancies, second-trimester estimated fetal weight below the 10th percentile and discordance of 15% or greater are associated with fetal growth restriction.

The effect of birthweight on childhood cognitive development in a middle-income country

BACKGROUND

Intra-uterine growth is a powerful predictor of infant mortality and of health, developmental and socioeconomic outcomes in adulthood. The question about whether this relationship is causal rather than driven by unobserved characteristics of low-weight infants is, however, still open. We use twin models to examine the hypothesis that in utero growth has a detrimental impact on cognitive development in childhood.

METHODS

We merge birth registry information on birthweight with standardized Math and Spanish test scores for all fourth graders in Chile to create a prospective data set. Twin fixed-effects models are used to estimate the causal effect of intra-uterine growth on test scores. Fixed-effect estimates are compared with traditional regression results in a cross-section of births to gauge the omitted variable bias emerging from unobserved genetic, maternal and pregnancy-related factors in cross-sectional models.

RESULTS

Birthweight differences within twin pairs have a substantial effect on test scores. A 400-g increase in birthweight results in a 15% standard deviation increase in Math scores. The effect is larger among (estimated) monozygotic than dizygotic pairs, reaching >20% standard deviation. The effect varies across family socioeconomic status. It is strong among disadvantaged families but it nearly disappears among advantaged ones.

CONCLUSION

Scarcity of uterine resources resulting in intra-uterine growth restriction has a detrimental effect on cognitive development in childhood. This effect interacts with family socioeconomic status (SES), so that low-SES families reinforce the effect of low birthweight and high-SES families fully compensate for it. Findings are particularly relevant in the developing world, where intra-uterine growth restriction is the main determinant of low birthweight.

Influence of gestational diabetes mellitus on weight discrepancy in twin pregnancies

OBJECTIVE

To evaluate the influence of gestational diabetes mellitus on weight discrepancy in twin pregnancies.

METHODS

200 twin pregnancies were included in the study. 157 nondiabetic pregnant women with twin gestations and 43 twin pregnancies with gestational diabetes mellitus (GDM) with viable fetuses born after 24 weeks of gestation were enrolled. Influence of maternal age, body-mass-index at the time of the oral glucose tolerance test, parity, smoking, chorionicity, gestational age at delivery and diagnosis of GDM on weight discrepancy of the twins was evaluated.

RESULTS

Mean weight discrepancy of all analyzed twin pregnancies was 285 grams (+/- 231), relative weight discrepancy was 11.3% (+/- 8.6). Univariate regression analyses showed that GDM, chorionicity and gestational age at delivery were significantly associated with weight discrepancy. In the multivariate model only diagnosis of GDM was significantly associated with weight discrepancy.

CONCLUSION

Twin pregnancies with insulin requiring gestational diabetes seem to have less birth weight discrepancy than twin pregnancies with normal glucose tolerance.

Oxidative stress in twin neonates is influenced by birth weight and weight discordance

OBJECTIVES

To evaluate the extent of oxidative stress in neonates born from multiple gestation pregnancies who are at high risk of prematurity and growth abnormalities.

DESIGN AND METHODS

Blood samples were collected from umbilical cord of 72 twins, born at gestational age of 28-38 weeks, and 20 consecutive control singletons. Oxidative stress parameters (15-F(2t)-isoprostane, a marker of lipid peroxidation, and total antioxidant capacity, tAOC), were measured in cord plasma.

RESULTS

Levels of 15-F(2t)-isoprostane showed a moderate negative correlation with birth weight and were higher in small co-twins of discordant pairs; tAOC was positively correlated with birth weight but no significant difference was found between co-twins.

CONCLUSIONS

Oxidative stress levels in twins are mainly influenced by birth weight and weight discordance. We suggest that evaluation of cord blood 15-F(2t)-isoprostane might be of clinical value as maker of pre- and perinatal distress in twinning.

Contributions of ischaemic placental disease to preterm birth in twin gestations

OBJECTIVE

To evaluate the extent to which ischaemic placental disease (IPD)--defined as women or newborns diagnosed with pre-eclampsia, small for gestational age (SGA), or abruption, is associated with preterm birth in twin gestations.

METHODS

A population-based study of women who delivered twin live births and stillbirths at 20-44 weeks gestation from 1995-2004 in the US was performed (n=1,105,666). We compared the frequency of IPD in term and preterm (<37 weeks) twin births. SGA was defined as twins with birthweight<10th percentile for gestational age, and corrected for infant sex. The association between IPD and preterm birth was expressed as hazard ratio, derived from Cox proportional hazard regression models after adjusting for potential confounders.

RESULTS

The overall rate of twin preterm birth was 57%. IPD was present in 20% of twin preterm births in comparison to a rate of 16% at term. Both pre-eclampsia and abruption, but not SGA, were associated with increased preterm birth rates. Women with two or more of the IPD conditions were more likely to deliver at preterm than at term gestations.

CONCLUSION

In comparison to twin births delivered at term, IPD is more common in preterm births. Efforts to understand the role of IPD in twin gestations based on preterm birth subtypes may reveal important insights.

One consequence of infertility treatment: multifetal pregnancy

This article discusses the issue of multifetal pregnancy as a result of fertility treatments. Pregnancies with multiple gestations are associated with serious infant and maternal health risks as well as psychological distress and significant financial consequences, and are a far too common consequence of infertility treatments such as assisted reproductive technology (ART) and ovulation induction drugs. Women with multifetal pregnancies are at a higher risk for multiple pregnancy complications and maternal morbidity/mortality as well as stress, depression, and anxiety disorders, especially when there is the threat of a loss of one or more fetuses. The rise in rates of multifetal gestation and the accompanying increased risk to both mother and fetuses have led the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology to develop guidelines to limit the number of transferred embryos during in vitro fertilization. Nurses who work with infertile women are in a position to educate them about the risks, benefits, and alternatives associated with ARTs and multifetal pregnancies, and should endeavor to learn as much as possible about this topic.

Ovine surgical model of uterine space restriction: interactive effects of uterine anomalies and multifetal gestations on fetal and placental growth

Intrauterine growth restriction (IUGR) is observed in conditions with limitations in uterine space (e.g., uterine anomalies and multifetal gestations). IUGR is associated with reduced fetal weight, organ growth, and a spectrum of adult-onset diseases. To examine the interaction of uterine anomalies and multifetal gestations, we developed a surgical uterine space restriction model with a unilateral uterine horn ligation before breeding (unilateral surgery). Placentas and fetuses were studied on Gestational Day (GD) 120 and GD 130 (term = 147 days). Unilateral surgery decreased placentome numbers in singleton and twin pregnancies (25% and 50%, respectively) but not unilateral triplets. Unilateral surgery decreased total placentome weight in twin pregnancies (decreased 24%). Fetuses categorized as uterine space restricted (unilateral twin and both groups of triplets) had 51% fewer placentomes per fetus and a 31% reduction in placentomal weight per fetus compared to the nonrestricted group (control singleton, unilateral singleton, and control twin). By GD 130, uterine space-restricted fetuses exhibited decreased weight, smaller crown-rump, abdominal girth, and thoracic girth as well as decreased fetal heart, kidney, liver, spleen, and thymus weights. Lung and brain weights were unaffected, demonstrating asymmetric IUGR. At GD 130, placental efficiency (fetal weight per total placentomal weight) was elevated in uterine space-restricted fetuses. However, fetal arterial creatinine, blood urea nitrogen, and cholesterol were elevated, suggesting insufficient placental clearance. Maternal-to-fetal glucose and triglycerides ratios were elevated in the uterine space-restricted pregnancies, suggesting placental nutrient transport insufficiency. This model allows for examination of interactive effects of uterine space restriction-induced IUGR on placental adaptation and fetal organ growth.

Epidemic of plurality and contributions of assisted reproductive technology therein

A commentary on contributions of ART to the pandemic of multiple gestations is presented and mechanistic aspects therein are explored.