The role of cell-free DNA biomarkers and patient data in the early prediction of preeclampsia: an artificial intelligence model.

BACKGROUND: Accurate individualized assessment of preeclampsia risk enables the identification of patients most likely to benefit from initiation of low-dose aspirin at 12 to 16 weeks of gestation when there is evidence for its effectiveness, and enables the guidance of appropriate pregnancy care pathways and surveillance. OBJECTIVE: The primary objective of this study was to evaluate the performance of artificial neural network models for the prediction of preterm preeclampsia (<37 weeks' gestation) using patient characteristics available at the first antenatal visit and data from prenatal cell-free DNA screening. Secondary outcomes were prediction of early-onset preeclampsia (<34 weeks' gestation) and term preeclampsia (≥37 weeks' gestation). METHODS: This secondary analysis of a prospective, multicenter, observational prenatal cell-free DNA screening study (SMART) included singleton pregnancies with known pregnancy outcomes. Thirteen patient characteristics that are routinely collected at the first prenatal visit and 2 characteristics of cell-free DNA (total cell-free DNA and fetal fraction) were used to develop predictive models for early-onset (<34 weeks), preterm (<37 weeks), and term (≥37 weeks) preeclampsia. For the models, the "reference" classifier was a shallow logistic regression model. We also explored several feedforward (nonlinear) neural network architectures with ≥1 hidden layers, and compared their performance with the logistic regression model. We selected a simple neural network model built with 1 hidden layer and made up of 15 units. RESULTS: Of the 17,520 participants included in the final analysis, 72 (0.4%) developed early-onset, 251 (1.4%) preterm, and 420 (2.4%) term preeclampsia. Median gestational age at cell-free DNA measurement was 12.6 weeks, and 2155 (12.3%) had their cell-free DNA measurement at ≥16 weeks' gestation. Preeclampsia was associated with higher total cell-free DNA (median, 362.3 vs 339.0 copies/mL cell-free DNA; P<.001) and lower fetal fraction (median, 7.5% vs 9.4%; P<.001). The expected, cross-validated area under the curve scores for early-onset, preterm, and term preeclampsia were 0.782, 0.801, and 0.712, respectively, for the logistic regression model, and 0.797, 0.800, and 0.713, respectively, for the neural network model. At a screen-positive rate of 15%, sensitivity for preterm preeclampsia was 58.4% (95% confidence interval, 0.569-0.599) for the logistic regression model and 59.3% (95% confidence interval, 0.578-0.608) for the neural network model. The contribution of both total cell-free DNA and fetal fraction to the prediction of term and preterm preeclampsia was negligible. For early-onset preeclampsia, removal of the total cell-free DNA and fetal fraction features from the neural network model was associated with a 6.9% decrease in sensitivity at a 15% screen-positive rate, from 54.9% (95% confidence interval, 52.9-56.9) to 48.0% (95% confidence interval, 45.0-51.0). CONCLUSION: Routinely available patient characteristics and cell-free DNA markers can be used to predict preeclampsia with performance comparable to that of other patient characteristic models for the prediction of preterm preeclampsia. Logistic regression and neural network models showed similar performance.

Impact of high-risk prenatal screening results for 22q11.2 deletion syndrome on obstetric and neonatal management: Secondary analysis from the SMART study.

OBJECTIVE: One goal of prenatal genetic screening is to optimize perinatal care and improve infant outcomes. We sought to determine whether high-risk cfDNA screening for 22q11.2 deletion syndrome (22q11.2DS) affected prenatal or neonatal management. METHODS: This was a secondary analysis from the SMART study. Patients with high-risk cfDNA results for 22q11.2DS were compared with the low-risk cohort for pregnancy characteristics and obstetrical management. To assess differences in neonatal care, we compared high-risk neonates without prenatal genetic confirmation with a 1:1 matched low-risk cohort. RESULTS: Of 18,020 eligible participants enrolled between 2015 and 2019, 38 (0.21%) were high-risk and 17,982 (99.79%) were low-risk for 22q11.2DS by cfDNA screening. High-risk participants had more prenatal diagnostic testing (55.3%; 21/38 vs. 2.0%; 352/17,982, p < 0.001) and fetal echocardiography (76.9%; 10/13 vs. 19.6%; 10/51, p < 0.001). High-risk newborns without prenatal diagnostic testing had higher rates of neonatal genetic testing (46.2%; 6/13 vs. 0%; 0/51, P < 0.001), echocardiography (30.8%; 4/13 vs. 4.0%; 2/50, p = 0.013), evaluation of calcium levels (46.2%; 6/13 vs. 4.1%; 2/49, P < 0.001) and lymphocyte count (53.8%; 7/13 vs. 15.7%; 8/51, p = 0.008). CONCLUSIONS: High-risk screening results for 22q11.2DS were associated with higher rates of prenatal and neonatal diagnostic genetic testing and other 22q11.2DS-specific evaluations. However, these interventions were not universally performed, and >50% of high-risk infants were discharged without genetic testing, representing possible missed opportunities to improve outcomes for affected individuals.

Performance of prenatal cfDNA screening for sex chromosomes.

PURPOSE: The aim of this study was to assess the performance of cell-free DNA (cfDNA) screening to detect sex chromosome aneuploidies (SCAs) in an unselected obstetrical population with genetic confirmation. METHODS: This was a planned secondary analysis of the multicenter, prospective SNP-based Microdeletion and Aneuploidy RegisTry (SMART) study. Patients receiving cfDNA results for autosomal aneuploidies and who had confirmatory genetic results for the relevant sex chromosomal aneuploidies were included. Screening performance for SCAs, including monosomy X (MX) and the sex chromosome trisomies (SCT: 47,XXX; 47,XXY; 47,XYY) was determined. Fetal sex concordance between cfDNA and genetic screening was also evaluated in euploid pregnancies. RESULTS: A total of 17,538 cases met inclusion criteria. Performance of cfDNA for MX, SCTs, and fetal sex was determined in 17,297, 10,333, and 14,486 pregnancies, respectively. Sensitivity, specificity, and positive predictive value (PPV) of cfDNA were 83.3%, 99.9%, and 22.7% for MX and 70.4%, 99.9%, and 82.6%, respectively, for the combined SCTs. The accuracy of fetal sex prediction by cfDNA was 100%. CONCLUSION: Screening performance of cfDNA for SCAs is comparable to that reported in other studies. The PPV for the SCTs was similar to the autosomal trisomies, whereas the PPV for MX was substantially lower. No discordance in fetal sex was observed between cfDNA and postnatal genetic screening in euploid pregnancies. These data will assist interpretation and counseling for cfDNA results for sex chromosomes.

Obstetrical, perinatal, and genetic outcomes associated with nonreportable prenatal cell-free DNA screening results.

BACKGROUND: The clinical implications of nonreportable cell-free DNA screening results are uncertain, but such results may indicate poor placental implantation in some cases and be associated with adverse obstetrical and perinatal outcomes. OBJECTIVE: This study aimed to assess the outcomes of pregnancies with nonreportable cell-free DNA screening in a cohort of patients with complete genetic and obstetrical outcomes. STUDY DESIGN: This was a prespecified secondary analysis of a multicenter prospective observational study of prenatal cell-free DNA screening for fetal aneuploidy and 22q11.2 deletion syndrome. Participants who underwent cell-free DNA screening from April 2015 through January 2019 were offered participation. Obstetrical outcomes and neonatal genetic testing results were collected from 21 primary-care and referral centers in the United States, Europe, and Australia. The primary outcome was risk for adverse obstetrical and perinatal outcomes (aneuploidy, preterm birth at <28, <34, and <37 weeks' gestation, preeclampsia, small for gestational age or birthweight <10th percentile for gestational week, and a composite outcome that included preterm birth at <37 weeks, preeclampsia, small for gestational age, and stillbirth at >20 weeks) after nonreportable cell-free DNA screening because of low fetal fraction or other causes. Multivariable analyses were performed, adjusting for variables known to be associated with obstetrical and perinatal outcomes, nonreportable results, or fetal fraction. RESULTS: In total, 25,199 pregnant individuals were screened, and 20,194 were enrolled. Genetic confirmation was missing in 1165 (5.8%), 1085 (5.4%) were lost to follow-up, and 93 (0.5%) withdrew; the final study cohort included 17,851 (88.4%) participants who had cell-free DNA, fetal or newborn genetic confirmatory testing, and obstetrical and perinatal outcomes collected. Results were nonreportable in 602 (3.4%) participants. A sample was redrawn and testing attempted again in 427; in 112 (26.2%) participants, results were again nonreportable. Nonreportable results were associated with higher body mass index, chronic hypertension, later gestational age, lower fetal fraction, and Black race. Trisomy 13, 18, or 21 was confirmed in 1.6% with nonreportable tests vs 0.7% with reported results (P=.013). Rates of preterm birth at <28, 34, and 37 weeks, preeclampsia, and the composite outcome were higher among participants with nonreportable results, and further increased among those with a second nonreportable test, whereas the rate of small for gestational age infants was not increased. After adjustment for confounders, the adjusted odds ratios were 2.2 (95% confidence interval, 1.1-4.4) and 2.6 (95% confidence interval, 0.6-10.8) for aneuploidy, and 1.5 (95% confidence interval, 1.2-1.8) and 2.1 (95% confidence interval, 1.4-3.2) for the composite outcome after a first and second nonreportable test, respectively. Of the patients with nonreportable tests, 94.9% had a live birth, as opposed to 98.8% of those with reported test results (adjusted odds ratio for livebirth, 0.20 [95% confidence interval, 0.13-0.30]). CONCLUSION: Patients with nonreportable cell-free DNA results are at increased risk for a number of adverse outcomes, including aneuploidy, preeclampsia, and preterm birth. They should be offered diagnostic genetic testing, and clinicians should be aware of the increased risk of pregnancy complications.

Cell-free DNA screening for prenatal detection of 22q11.2 deletion syndrome.

BACKGROUND: Historically, prenatal screening has focused primarily on the detection of fetal aneuploidies. Cell-free DNA now enables noninvasive screening for subchromosomal copy number variants, including 22q11.2 deletion syndrome (or DiGeorge syndrome), which is the most common microdeletion and a leading cause of congenital heart defects and neurodevelopmental delay. Although smaller studies have demonstrated the feasibility of screening for 22q11.2 deletion syndrome, large cohort studies with confirmatory postnatal testing to assess test performance have not been reported. OBJECTIVE: This study aimed to assess the performance of single-nucleotide polymorphism-based, prenatal cell-free DNA screening for detection of 22q11.2 deletion syndrome. STUDY DESIGN: Patients who underwent single-nucleotide polymorphism-based prenatal cell-free DNA screening for 22q11.2 deletion syndrome were prospectively enrolled at 21 centers in 6 countries. Prenatal or newborn DNA samples were requested in all cases for genetic confirmation using chromosomal microarrays. The primary outcome was sensitivity, specificity, positive predictive value, and negative predictive value of cell-free DNA screening for the detection of all deletions, including the classical deletion and nested deletions that are ≥500 kb, in the 22q11.2 low-copy repeat A-D region. Secondary outcomes included the prevalence of 22q11.2 deletion syndrome and performance of an updated cell-free DNA algorithm that was evaluated with blinding to the pregnancy outcome. RESULTS: Of the 20,887 women enrolled, a genetic outcome was available for 18,289 (87.6%). A total of 12 22q11.2 deletion syndrome cases were confirmed in the cohort, including 5 (41.7%) nested deletions, yielding a prevalence of 1 in 1524. In the total cohort, cell-free DNA screening identified 17,976 (98.3%) cases as low risk for 22q11.2 deletion syndrome and 38 (0.2%) cases as high risk; 275 (1.5%) cases were nonreportable. Overall, 9 of 12 cases of 22q11.2 were detected, yielding a sensitivity of 75.0% (95% confidence interval, 42.8-94.5); specificity of 99.84% (95% confidence interval, 99.77-99.89); positive predictive value of 23.7% (95% confidence interval, 11.44-40.24), and negative predictive value of 99.98% (95% confidence interval, 99.95-100). None of the cases with a nonreportable result was diagnosed with 22q11.2 deletion syndrome. The updated algorithm detected 10 of 12 cases (83.3%; 95% confidence interval, 51.6-97.9) with a lower false positive rate (0.05% vs 0.16%; P<.001) and a positive predictive value of 52.6% (10/19; 95% confidence interval, 28.9-75.6). CONCLUSION: Noninvasive cell-free DNA prenatal screening for 22q11.2 deletion syndrome can detect most affected cases, including smaller nested deletions, with a low false positive rate.

Cell-free DNA screening for trisomies 21, 18, and 13 in pregnancies at low and high risk for aneuploidy with genetic confirmation.

BACKGROUND: Cell-free DNA noninvasive prenatal screening for trisomies 21, 18, and 13 has been rapidly adopted into clinical practice. However, previous studies are limited by a lack of follow-up genetic testing to confirm the outcomes and accurately assess test performance, particularly in women at a low risk for aneuploidy. OBJECTIVE: To measure and compare the performance of cell-free DNA screening for trisomies 21, 18, and 13 between women at a low and high risk for aneuploidy in a large, prospective cohort with genetic confirmation of results STUDY DESIGN: This was a multicenter prospective observational study at 21 centers in 6 countries. Women who had single-nucleotide-polymorphism-based cell-free DNA screening for trisomies 21, 18, and 13 were enrolled. Genetic confirmation was obtained from prenatal or newborn DNA samples. The test performance and test failure (no-call) rates were assessed for the cohort, and women with low and high previous risks for aneuploidy were compared. An updated cell-free DNA algorithm blinded to the pregnancy outcome was also assessed. RESULTS: A total of 20,194 women were enrolled at a median gestational age of 12.6 weeks (interquartile range, 11.6-13.9). The genetic outcomes were confirmed in 17,851 cases (88.4%): 13,043 (73.1%) low-risk and 4808 (26.9%) high-risk cases for aneuploidy. Overall, 133 trisomies were diagnosed (100 trisomy 21; 18 trisomy 18; 15 trisomy 13). The cell-free DNA screen positive rate was lower in the low-risk vs the high-risk group (0.27% vs 2.2%; P<.0001). The sensitivity and specificity were similar between the groups. The positive predictive value for the low- and high-risk groups was 85.7% vs 97.5%; P=.058 for trisomy 21; 50.0% vs 81.3%; P=.283 for trisomy 18; and 62.5% vs 83.3; P=.58 for trisomy 13, respectively. Overall, 602 (3.4%) patients had no-call result after the first draw and 287 (1.61%) after including cases with a second draw. The trisomy rate was higher in the 287 cases with no-call results than patients with a result on a first draw (2.8% vs 0.7%; P=.001). The updated algorithm showed similar sensitivity and specificity to the study algorithm with a lower no-call rate. CONCLUSION: In women at a low risk for aneuploidy, single-nucleotide-polymorphism-based cell-free DNA has high sensitivity and specificity, positive predictive value of 85.7% for trisomy 21 and 74.3% for the 3 common trisomies. Patients who receive a no-call result are at an increased risk of aneuploidy and require additional investigation.

Fetal Exosomal Platelet-activating Factor Triggers Functional Progesterone Withdrawal in Human Placenta.

In most mammals, labor is heralded by the withdrawal of progesterone. In humans, circulating progesterone levels increase as gestation advances while placental expression of progesterone receptor A (PR-A) declines. As a result of PR-A downregulation, the non-canonical NF-κB pathway is activated, an event implicated in triggering labor. Here, we sought to identify fetal-derived mediator(s) that represses placental PR-A in human placenta leading to activation of pro-labor signaling. Lipidomic profiling demonstrated enrichment of platelet-activating factor (PAF) in exosomes originating from the human fetus. Exposure of primary cytotrophoblasts to fetal exosomes from term pregnancies reduced PR-A expression by > 50%, and PAF also reduced PR-A message levels in a dose-dependent manner. Notably, fetal exosomes from preterm pregnancies had lower PAF levels and no effect on PR-A expression. Synthetic PAF-induced DNA methylation increases by 20% at the PR-A promoter, leading to recruitment of corepressors and downregulation of PR-A in cytotrophoblast. Furthermore, suppression of PR-A by PAF-stimulated expression of the pro-labor genes, corticotropin-releasing hormone (CRH) and cyclooxygenase-2 (COX-2), which was reversed by disruption of the DNA methyltransferases 3B and 3L. Taken together, PAF represents a novel fetal-derived candidate for initiation of labor by stimulating methylation and repression of PR-A and activating pro-labor signaling in trophoblast.

Mode of Delivery in Stillbirth, 1995-2004.

OBJECTIVE: There are no national reports on the mode of delivery in pregnancies that end in stillbirth. We aimed at analyzing the cesarean delivery rates in pregnancies resulting in stillbirth over a 10-year period in the United States. MATERIALS AND METHODS: This was a retrospective analysis evaluating data from the 1995 to 2004 US linked live birth-infant death files reported by the National Center for Health Statistics to examine the cesarean delivery rates in singleton pregnancies with and without stillbirth. RESULTS: There were 39 797 616 singleton births registered in the database after the 20th week of gestation. During the study period, there were 243 979 stillbirths (0.61 per 100). Significant differences in stillbirths were noted in the African American population, nonmarried patients, in mothers who smoked, and at the extremes of the patients reproductive age (P < .01). The overall cesarean delivery rate in liveborn was 23.54% (9 309 961 cases) and 10.5% in stillbirth (25 558 cases; P < .01). The rate of cesarean delivery increased in liveborn (from 20.8% in 1995 to 28.9% in 2004; 28% overall increase) and in stillbirth (9.5% in 1995 to 11.23% in 2004; 15% overall increase). The rates of primary and repeat cesarean operations increased with gestational age in the stillbirth group. This pattern was not observed in the liveborn group. CONCLUSION: This analysis indicates that the cesarean delivery rates increased both in liveborn and in stillbirth from 1995 to 2004. This epidemiological observation deserves new clinical investigations to understand the clinical reasons, driving this obstetrical practice and the financial and societal impact that it portends.

Screening for Down syndrome in dichorionic twin pregnancies conceived by in vitro fertilization (IVF): a clinical pilot study to confirm the laboratory methods.

PURPOSE: The corrections necessary to estimate the risk for Down syndrome in twin pregnancies have been pointed out. We performed a nested controlled study to evaluate the validity of these corrections in dichorionic twins conceived by IVF. METHODS: Detailed clinical data was collected from the medical records. Twins were matched with a contemporaneous cohort of spontaneously conceived singleton pregnancies that serve as reference in a 1 to 4 ratio. All patients had their entire obstetrical care at our Hospital. The Student t-test was used for group comparisons and a p-value <0.05 was considered significant. RESULTS: Nineteen sets of normal twins concordant in size and with appropriate weight for gestational age were matched with 80 normal and mature newborns. Significant differences between groups were found for maternal age, gestational age at delivery and newborn weight (all p < 0.01). No statistical differences were noted for the levels of the biochemical markers expressed as multiples of the median. However, a 15 % closer approximation to the laboratory median for PAPP-A and a 10 % closer approximation to the laboratory median for free ß-hCG was evident in twins when compared to the reference group. CONCLUSIONS: These findings support the methods used to estimate the risk for Down syndrome in dichorionic twin pregnancies conceived after IVF. A future study with a larger sample size could confirm if the laboratory corrections done on the combined screening test improve the predictability of Down syndrome in dichorionic twin pregnancy conceived by IVF when compared to singleton pregnancies.

Paternal age and risk for cesarean delivery.

OBJECTIVE: To determine whether advanced paternal age is associated with increased risk for cesarean delivery. STUDY DESIGN: We used the 1990-2002 US linked live birth and infant death data files restricted to primiparous Caucasian and African-American women that delivered a singleton birth at ≥20 week's gestation (12.5 million). We examined temporal trends and risk ratios of cesarean birth in relation to paternal age before and after adjustments for known confounders. RESULTS: Among Caucasians, the cesarean delivery rates were 21.1%, 26.7% and 31.8% in fathers aged 20-29, 30-39 and ≥40 years, respectively. Among African-Americans, the corresponding rates were 24.1%, 33.2%, and 38.1%, respectively. These increased cesarean delivery rates persisted in analyses stratified by maternal age before and after adjustment for a variety of confounders. CONCLUSIONS: These findings suggest that increasing paternal age may be associated with an increased risk for cesarean delivery in primiparous women.

Twins--twice more trouble?

Twin gestations are fascinating and are also high-risk pregnancies. They account for approximately 3% of all pregnancies in the United States. Major obstetrical complications associated with twin pregnancies include hypertensive disorders of pregnancy, gestational diabetes, and preterm delivery. In addition, the death rate for twins and the rate of severe handicap in very low birth weight survivors of twin pregnancies is greater than that for singleton pregnancies. Ultrasound allows for stepwise evaluations at any time during a twin gestation. Current evidence suggests that uncomplicated diamniotic twins with concordant and appropriate growth beyond 24 weeks' gestation should be managed conservatively and the time and mode of delivery should be determined on the basis of obstetrical history and fetal presentations. Perinatal management of the remaining twin pregnancies depends on good clinical judgment, which is improved by the use of ultrasound imaging.