Clinical implications of crown-rump length discordance at 11 to 14 weeks in dichorionic twins.

BACKGROUND: Crown-rump length discordance, defined as ≥10% discordance, has been investigated as an early sonographic marker of subsequent growth abnormalities and is associated with an increased risk of fetal loss in twin pregnancies. Previous studies have not investigated the prevalence of fetal aneuploidy or structural anomalies in twins with discordance or the independent association of crown-rump length discordance with adverse perinatal outcomes. Moreover, data are limited on cell-free DNA screening for aneuploidy in dichorionic twins with discordance. OBJECTIVE: This study aimed to evaluate whether crown-rump length discordance in dichorionic twins between 11 and 14 weeks of gestation is associated with a higher risk of aneuploidy, structural anomalies, or adverse perinatal outcomes and to assess the performance of cell-free DNA screening in dichorionic twin pregnancies with crown-rump length discordance. STUDY DESIGN: This was a secondary analysis of a multicenter retrospective cohort study that evaluated the performance of cell-free DNA screening for the common trisomies in twin pregnancies from December 2011 to February 2020. For this secondary analysis, we included live dichorionic pregnancies with crown-rump length measurements between 11 and 14 weeks of gestation. First, we compared twin pregnancies with discordant crown-rump lengths with twin pregnancies with concordant crown-rump lengths and analyzed the prevalence of aneuploidy and fetal structural anomalies in either twin. Second, we compared the prevalence of a composite adverse perinatal outcome, which included preterm birth at <34 weeks of gestation, hypertensive disorders of pregnancy, stillbirth or miscarriage, small-for-gestational-age birthweight, and birthweight discordance. Moreover, we assessed the performance of cell-free DNA screening in pregnancies with and without crown-rump length discordance. Outcomes were compared with multivariable regression to adjust for confounders. RESULTS: Of 987 dichorionic twins, 142 (14%) had crown-rump length discordance. The prevalence of aneuploidy was higher in twins with crown-rump length discordance than in twins with concordance (9.9% vs 3.9%, respectively; adjusted relative risk, 2.7; 95% confidence interval, 1.4-4.9). Similarly, structural anomalies (adjusted relative risk, 2.5; 95% confidence interval, 1.4-4.4]) and composite adverse perinatal outcomes (adjusted relative risk, 1.2; 95% confidence interval, 1.04-1.3) were significantly higher in twins with discordance. A stratified analysis demonstrated that even without other ultrasound markers, there were increased risks of aneuploidy (adjusted relative risk, 3.5; 95% confidence interval, 1.5-8.4) and structural anomalies (adjusted relative risk, 2.7; 95% confidence interval, 1.5-4.8) in twins with CRL discordance. Cell-free DNA screening had high negative predictive values for trisomy 21, trisomy 18, and trisomy 13, regardless of crown-rump length discordance, with 1 false-negative for trisomy 21 in a twin pregnancy with discordance. CONCLUSION: Crown-rump length discordance in dichorionic twins is associated with an increased risk of aneuploidy, structural anomalies, and adverse perinatal outcomes, even without other sonographic abnormalities. Cell-free DNA screening demonstrated high sensitivity and negative predictive values irrespective of crown-rump length discordance; however, 1 false-negative result illustrated that there is a role for diagnostic testing. These data may prove useful in identifying twin pregnancies that may benefit from increased screening and surveillance and are not ascertained by other early sonographic markers.

Cell-free DNA screening for trisomy 21 in twin pregnancy: a large multicenter cohort study.

BACKGROUND: Analysis of cell-free DNA from maternal blood provides effective screening for trisomy 21 in singleton pregnancies. Data on cell-free DNA screening in twin gestations are promising although limited. In previous twin studies, cell-free DNA screening was primarily performed in the second trimester and many studies did not report chorionicity. OBJECTIVE: This study aimed to evaluate the screening performance of cell-free DNA for trisomy 21 in twin pregnancies in a large, diverse cohort. A secondary aim was to evaluate screening performance for trisomy 18 and trisomy 13. STUDY DESIGN: This was a retrospective cohort study of twin pregnancies from 17 centers for which cell-free DNA screening was performed from December 2011 to February 2020 by one laboratory using massively parallel sequencing technology. Medical record review was conducted for all newborns and data on the birth outcome, the presence of any congenital abnormalities, phenotypic appearance at birth, and any chromosomal testing that was undertaken in the antenatal or postnatal period were extracted. Cases with a possible fetal chromosomal abnormality with no genetic test results were reviewed by a committee of maternal-fetal medicine geneticists. Cases with a vanishing twin and inadequate follow-up information were excluded. A minimum of 35 confirmed cases of trisomy 21 was required to capture a sensitivity of at least 90% with a prevalence of at least 1.9% with 80% power. Test characteristics were calculated for each outcome. RESULTS: A total of 1764 samples were sent for twin cell-free DNA screening. Of those, 78 cases with a vanishing twin and 239 cases with inadequate follow-up were excluded, leaving a total of 1447 cases for inclusion in the analysis. The median maternal age was 35 years and the median gestational age at cell-free DNA testing was 12.3 weeks. In total, 81% of the twins were dichorionic. The median fetal fraction was 12.4%. Trisomy 21 was detected in 41 of 42 pregnancies, yielding a detection rate of 97.6% (95% confidence interval, 83.8-99.7). There was 1 false negative and no false positive cases. Trisomy 21 was detected in 38 out of 39 dichorionic twin pregnancies, yielding a detection rate of 97.4% (95% confidence interval, 82.6-99.7). Trisomy 18 was detected in 10 of the 10 affected pregnancies. There was 1 false positive case. Trisomy 13 was detected in 4 of the 5 cases, yielding a detection rate of 80% (95% confidence interval, 11.1-99.2). There was one false negative and no false positive cases. The nonreportable rate was low at 3.9 %. CONCLUSION: Cell-free DNA testing is effective in screening for trisomy 21 in twin gestations from the first trimester of pregnancy. Detection of trisomy 21 was high in dichorionic and monochorionic twins, and the nonreportable result rates were low. This study included high numbers of cases of trisomy 18 and 13 when compared with the current literature. Although screening for these conditions in twins seems to be promising, the numbers were too small to make definitive conclusions regarding the screening efficacy for these conditions. It is possible that cell-free DNA testing performance may differ among laboratories and vary with screening methodologies.

MicroRNA Signature of Epithelial-Mesenchymal Transition in Group B Streptococcal Infection of the Placental Chorioamniotic Membranes.

BACKGROUND: Infection-induced preterm birth is a major cause of neonatal mortality and morbidity and leads to preterm premature rupture of placental chorioamniotic membranes. The loss of amniotic epithelial cells and tensile strength preceding membrane rupture is poorly understood. We hypothesized that intrauterine bacterial infection induces changes in microRNA (miRNA) expression, leading to amniotic epithelial cell loss and membrane weakening. METHODS: Ten pregnant pigtail macaques received choriodecidual inoculation of either group B Streptococcus (GBS) or saline (n = 5/group). Placental chorioamniotic membranes were studied using RNA microarray and immunohistochemistry. Chorioamniotic membranes from women with preterm premature rupture of membranes (pPROM) and normal term pregnancies were studied using transmission electron microscopy. RESULTS: In our model, an experimental GBS infection was associated with changes in the miRNA profile in the chorioamniotic membranes consistent with epithelial to mesenchymal transition (EMT) with loss of epithelial (E-cadherin) and gain of mesenchymal (vimentin) markers. Similarly, loss of desmosomes (intercellular junctions) was seen in placental tissues from women with pPROM. CONCLUSIONS: We describe EMT as a novel mechanism for infection-associated chorioamniotic membrane weakening, which may be a common pathway for many etiologies of pPROM. Therapy based on anti-miRNA targeting of EMT may prevent pPROM due to perinatal infection.

Choriodecidual Group B Streptococcal Infection Induces miR-155-5p in the Fetal Lung in Macaca nemestrina.

The mechanisms underlying fetal lung injury remain poorly defined. MicroRNAs (miRNAs) are small noncoding, endogenous RNAs that regulate gene expression and have been implicated in the pathogenesis of lung disease. Using a nonhuman primate model of choriodecidual infection, we sought to determine if differentially expressed miRNAs were associated with acute fetal lung injury. After inoculating 10 chronically catheterized pregnant monkeys (Macaca nemestrina) with either group B streptococcus (GBS) at 1 × 10(6) CFU (n = 5) or saline (n = 5) in the choriodecidual space, we extracted fetal lung mRNA and miRNA and profiled the changes in expression by microarray analysis. We identified 9 differentially expressed miRNAs in GBS-exposed fetal lungs, but of these, only miR-155-5p was validated by quantitative reverse transcription-PCR (P = 0.02). Significantly elevated miR-155-5p expression was also observed when immortalized human fetal airway epithelial (FeAE) cells were exposed to proinflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNF-α]). Overexpression of miR-155-5p in FeAE cells in turn increased the production of IL-6 and CXCL10/gamma interferon-induced protein 10, which are implicated in leukocyte recruitment but also in protection from lung injury. Interestingly, while miR-155-5p decreased fibroblast growth factor 9 (FGF9) expression in a luciferase reporter assay, FGF9 levels were actually increased in GBS-exposed fetal lungs in vivo. FGF9 overexpression is associated with abnormal lung development. Thus, upregulation of miR-155-5p may serve as a compensatory mechanism to lessen the increase in FGF9 and prevent aberrant lung development. Understanding the complicated networks regulating lung development in the setting of infection is a key step in identifying how to prevent fetal lung injury leading to bronchopulmonary dysplasia.

Examining the correlation between placental and serum placenta growth factor in preeclampsia.

OBJECTIVE: Decreased levels of serum placenta growth factor (PlGF) are associated with preeclampsia. We sought to determine whether serum and placental levels of PlGF (sPlGF and pPlGF) are associated with preeclampsia and whether there is a correlation between serum and placental PlGF levels. STUDY DESIGN: These analyses were part of a larger, prospective, case-control study. Cases were women with preeclampsia. Controls were women without preeclampsia who delivered at term. Analyses included nonparametric tests to compare medians, logistic regression to estimate odds, and calculation of correlation coefficients. RESULTS: Twenty-four cases (10 preterm, 14 term) were compared with 14 controls. Median levels of PlGF were significantly lower in cases than controls (pPlGF: 232.6 vs 363.4 pg/mL, P = .02; sPlGF: 85.5 vs 274.4 pg/mL, P < .001). Serum and placental PlGF were correlated (overall: 39%, P = .006; cases with preterm preeclampsia and growth restriction: 87%, P = .02). CONCLUSION: Serum and placental PlGF are independently associated with preeclampsia and correlated with each other.

Comparing postcesarean infectious complication rates using two different skin preparations.

OBJECTIVE: To estimate whether a new preoperative skin preparation protocol decreases postcesarean delivery infectious complications. METHODS: We performed a retrospective cohort study. A povidone-iodine (13%) scrub followed by povidone-iodine (10%) paint (SCRUB+PAINT) protocol was compared with standard paint alone (PAINT). Patients and outcomes were identified using diagnosis-related group and International Classification of Diseases, 9th Revision, Clinical Modification coding. Monthly infection rates before the new protocol (October 1, 2007-September 30, 2008) were compared with rates after the protocol (January 1, 2009-December 31, 2009). The primary and secondary outcomes were major puerperal infection and a composite of major puerperal infection and infectious wound complications. Poisson regression was used to model monthly infection rates over time while controlling for confounders known to contribute to infectious risk. RESULTS: Data from 2,143 patients (PAINT: n=1,139; SCRUB+PAINT: n=1,004) were included in the analysis. There was no significant secular trend of decreasing infections over time before initiating SCRUB+PAINT (P=.42). SCRUB+PAINT was associated with a decrease in major puerperal infection (3.4 compared with 5.4/100 cesarean deliveries, P=.03) and composite wound infection (5.5 compared with 7.8/100 cesarean deliveries, P=.03) compared with PAINT alone. SCRUB+PAINT resulted in a 38% reduction in major puerperal infection (incident rate ratio 0.62 [0.42-0.93], P=.02) and a 31% reduction in composite wound infection (incident rate ratio 0.69 [0.50-0.96], P=.03) after controlling for confounders and fluctuations in the rates over time. CONCLUSION: The SCRUB+PAINT protocol is associated with a decrease in the rate of postcesarean delivery infectious complications compared with using povidone-iodine topical paint alone.