Anticoagulation use is associated with lower fetal fraction and more indeterminate results.

BACKGROUND: Maternal anticoagulation use may increase indeterminate result rates on cell-free DNA-based screening, but existing studies are confounded by inclusion of individuals with autoimmune disease, which alone is associated with indeterminate results. Changes in chromosome level Z-scores are proposed by others as a reason for indeterminate results, but the etiology of this is uncertain. OBJECTIVE: This study aimed to evaluate differences in fetal fraction, indeterminate result rate, and total cell-free DNA concentration in individuals on anticoagulation without autoimmune disease compared with controls undergoing noninvasive prenatal screening. Secondly, using a nested case-control design, we evaluated differences in fragment size, GC-content, and Z-scores to evaluate laboratory-level test characteristics. STUDY DESIGN: This was a retrospective single-institution study of pregnant individuals undergoing cell-free DNA-based noninvasive prenatal screening using low-pass whole-genome sequencing between 2017 and 2021. Individuals with autoimmune disease, suspected aneuploidy, and cases where fetal fraction was not reported were excluded. Anticoagulation included heparin-derived products (unfractionated heparin, low-molecular-weight heparin), clopidogrel, and fondaparinux, with a separate group for those on aspirin alone. An indeterminate result was defined as fetal fraction <4%. We evaluated the association between maternal anticoagulation or aspirin use, and fetal fraction, indeterminate results, and total cell-free DNA concentration using univariate and multivariate analyses, controlling for body mass index, gestational age at sample collection, and fetal sex. For the anticoagulation cohort, we compared laboratory-level test characteristics among cases (on anticoagulation) and a subset of controls. Lastly, we evaluated for differences in chromosome level Z-scores among those on anticoagulation with and without indeterminate results. RESULTS: A total of 1707 pregnant individuals met the inclusion criteria. Of those, 29 were on anticoagulation and 81 were on aspirin alone. For those on anticoagulation, the fetal fraction was significantly lower (9.3% vs 11.7%; P<.01), the indeterminate result rate was significantly higher (17.2% vs 2.7%; P<.001), and the total cell-free DNA concentration was significantly higher (218 pg/µL vs 83.7 pg/µL; P<.001). Among those on aspirin alone, the fetal fraction was lower (10.6% vs 11.8%; P=.04); however, there were no differences in the rate of indeterminate results (3.7% vs 2.7%; P=.57) or total cell-free DNA concentration (90.1 pg/µL vs 83.8 pg/µL; P=.31). After controlling for maternal body mass index, gestational age at sample collection, and fetal sex, anticoagulation was associated with an >8-fold increase in the likelihood of an indeterminate result (adjusted odds ratio, 8.7; 95% confidence interval, 3.1-24.9; P<.001), but not aspirin (adjusted odds ratio, 1.2; 95% confidence interval, 0.3-4.1; P=.8). Anticoagulation was not associated with appreciable differences in cell-free DNA fragment size or GC-content. Although differences in chromosome 13 Z-scores were observed, none were observed for chromosomes 18 or 21, and this difference did not contribute to the indeterminate result call. CONCLUSION: In the absence of autoimmune disease, anticoagulation use, but not aspirin, is associated with lower fetal fraction, higher total cell-free DNA concentration, and higher rates of indeterminate results. Anticoagulation use was not accompanied by differences in cell-free DNA fragment size or GC-content. Statistical differences in chromosome level Z-scores did not clinically affect aneuploidy detection. This suggests a likely dilutional effect by anticoagulation on cell-free DNA-based noninvasive prenatal screening assays contributing to low fetal fraction and indeterminate results, and not laboratory or sequencing-level changes.

Association of fetal fraction with hypertensive disorders of pregnancy incidence and disease severity.

BACKGROUND: Hypertensive disorders of pregnancy contribute to maternal and offspring morbidity and mortality. Studies suggest that a lower early pregnancy fetal fraction is associated with an increased risk of hypertensive disorders of pregnancy. However, maternal obesity significantly affects fetal fraction and is a risk factor for hypertensive disorders of pregnancy. OBJECTIVE: We determined the association between fetal fraction (using a standardized single-institution platform, including male and female fetuses) and hypertensive disorders of pregnancy, stratified by obesity status. Second, we evaluated differences in total cell-free DNA concentration and correlation of fetal fraction with clinical markers of hypertensive disorders of pregnancy severity. STUDY DESIGN: This was a retrospective, single-institution study of a previously validated cell-free DNA-based noninvasive prenatal screening assay of 1058 samples. Maternal body mass index at the time of noninvasive prenatal screening was assessed, and hypertensive disorders of pregnancy were confirmed by a detailed medical record review. Differences in fetal fraction and total cell-free DNA concentration between the groups were assessed with univariate analyses. Multivariable regression was used to evaluate the association between fetal fraction and hypertensive disorders of pregnancy, adjusted for body mass index, maternal age, gestational age at noninvasive prenatal screening, and fetal sex. The association between fetal fraction and hypertensive disorders of pregnancy among individuals with obesity (body mass index, ≥30 kg/m2) and individuals without obesity (body mass index, <30 kg/m2) was investigated while controlling for the aforementioned covariates. Lastly, multivariable linear regression was used to evaluate the association between fetal fraction and clinical markers of hypertensive disorders of pregnancy severity. RESULTS: We identified individuals with (n=117) and without (n=941) hypertensive disorders of pregnancy with noninvasive prenatal screening drawn before 20 weeks of gestation and with fetal fraction and body mass index data available. Those with hypertensive disorders of pregnancy had a lower fetal fraction (10.2%±4.2% vs 11.6%±4.7%; P<.01), without differences in total cell-free DNA concentration (P=.14). When groups were stratified by obesity status, this relationship was only valid for individuals without obesity (P=.02). Only when logistic regression analysis was restricted to individuals without obesity did the likelihood of hypertensive disorders of pregnancy rise with decreasing fetal fraction (odds ratio, 0.93; 95% confidence interval, 0.88-0.99; P=.02). In addition, fetal fraction was inversely associated with maximum systolic blood pressure at the time of hypertensive disorders of pregnancy only in the population without obesity (ß, -0.08; 95% confidence interval, -0.147 to -0.01; P=.02). CONCLUSION: Although a lower fetal fraction is associated with the development of hypertensive disorders of pregnancy, the use of this parameter for the prediction may be problematic in individuals with obesity, as obesity has such a profound effect on fetal fraction. However, we uniquely noted that among individuals without obesity, fetal fraction is lower for those that develop hypertensive disorders of pregnancy and lower fetal fraction increases the odds of hypertensive disorders of pregnancy development. Lastly, low fetal fraction in the population without obesity that developed hypertensive disorders of pregnancy was associated with higher systolic blood pressure at the time of hypertensive disorders of pregnancy, an important clinical marker of hypertensive disorders of pregnancy severity. As analytical approaches of cell-free DNA interrogation advance, the prediction of placental-mediated disorders with first-trimester sampling is likely to improve, although this may remain challenging in gravidas with obesity, a cohort at high risk of developing hypertensive disorders of pregnancy.

JTH in Clinic - Obstetric bleeding: VWD and other inherited bleeding disorders.

Individuals with inherited bleeding disorders (IBDs) have higher bleeding risk during pregnancy, childbirth, and the postpartum period. Clinical management requires recognition of the IBD as high risk for postpartum hemorrhage and a personalized multidisciplinary approach that includes the patient in decision making. When the fetus is known or at risk to inherit a bleeding disorder, fetal and neonatal bleeding risk also need to be considered. In pregnant IBD patients, it is common for providers to need to make decisions in the absence of high level of certainty evidence. We here present the case of a pregnant von Willebrand disease patient that reached multiple decision points where there is currently clinical ambiguity due to a lack of high level of certainty evidence. For each stage of her care, from diagnosis to the postpartum period, we discuss current literature and describe our approach. This is followed by a brief overview of considerations in other IBDs and pregnancy.

Increased length of active labor is associated with adverse perinatal outcomes among nulliparous women undergoing labor induction.

OBJECTIVE: Evaluate the association between current recommendations for active labor duration in nulliparous women undergoing labor induction and adverse perinatal outcomes. STUDY DESIGN: Retrospective cohort study from 2012 to 2015. Subjects were nulliparous, 18-44 years, cephalic, singleton ≥37 weeks undergoing labor induction who reached active labor. We created three subgroups, defined by active labor duration from 6 to 10cm as < the median, median-95th percentile, and >95th percentile based on contemporary labor curves. We evaluated the association between subgroups and cesarean delivery, chorioamnionitis, blood loss (EBL), 5-minute Apgar score < 7, and neonatal intensive care unit (NICU) admission using logistic regression. RESULTS: Among 356 women, 34.8% had an active labor duration < median, 43.3% were between the median-95th percentile, and 21.9% were >95th percentile. The risk of cesarean delivery increased with longer active labor duration; 1.8-fold (95%CI = 1.1-3.1) and 4.0-fold (95%CI = 2.5-6.5) for women whose active labors were between the median-95th percentile and >95th percentile, respectively. Chorioamnionitis increased by 3.9-fold (95%CI = 1.2-13.2) in the >95th percentile subgroup. Active labor length was not associated with EBL, Apgar scores, or NICU admission. CONCLUSIONS: Cesarean delivery and chorioamnionitis increased significantly as induced active labor duration exceeded the median. This study provides a better understanding regarding the risks of longer active labor as defined by contemporary labor curves.

The impact of maternal autoimmune disease on cell-free DNA test characteristics.

BACKGROUND: Maternal biologic factors can affect the fetal fraction in cell-free DNA-based prenatal screening assays, thereby limiting the effectiveness. Higher rates of indeterminate results because of a low fetal fraction have been described in cases of maternal autoimmune disease in pregnancy. Existing studies are confounded by the concomitant maternal use of anticoagulants, which may independently influence the test characteristics. OBJECTIVE: This study aimed to evaluate the differences in fetal fraction, indeterminate results, and total cell-free DNA concentration among women with an autoimmune disease in comparison with controls, using our in-house developed, noninvasive prenatal screening platform in the absence of maternal anticoagulation use. STUDY DESIGN: This was a retrospective, single institution cohort study of a previously validated, cell-free DNA-based, noninvasive prenatal screening assay using a low-pass whole-genome sequencing platform between 2017 and 2019. A diagnosis of an autoimmune disease included systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, and others. Immunomodulator therapies included biologics, corticosteroids, hydroxychloroquine, azathioprine, and intravenous immunoglobulin. Women who were using anticoagulants were excluded. We evaluated the association between autoimmune disease and fetal cell-free DNA fraction, indeterminate results, and total cell-free DNA concentration using univariate and multivariate analyses, stratified according to immunomodulator therapy and adjusted for body mass index, fetal sex, and gestational age at sample collection. RESULTS: A total of 1445 patients met inclusion criteria. Of those, 43 women had a confirmed autoimmune disease, with 25 of those not on immunomodulator therapy and 18 on immunomodulator therapy. The mean fetal fraction for women with an autoimmune disease was significantly lower than for controls (9.7% vs 11.9%; P=.004). The rate of indeterminate results was significantly higher among women with an autoimmune disease than among controls (16.3% vs 3.5%; P<.001). The total cell-free DNA concentration was not statistically different between the groups (94.8 pg/µL for women with an autoimmune disease vs 83.9 pg/µL for controls; P=.06). In a logistic regression, women with an autoimmune disease had significantly higher odds of receiving an indeterminate result than controls, (adjusted odds ratio, 5.3; 95% confidence interval, 2.0-14.2). Linear regression analysis showed a significant negative association between having an autoimmune disease and the fetal cell-free DNA fraction (aß, -2.1; 95% confidence interval, -3.4 to -0.6). When stratifying by treatment status, the mean fetal fraction was 9.8%, 9.6%, and 11.9% for women with an autoimmune disease not on immunomodulator therapy, women with an autoimmune disease on immunomodulator therapy, and the controls, respectively (P=.02). The rate of indeterminate results increased in a stepwise fashion from 3.5% to 11.1% to 20.0% for controls, women with an autoimmune disease on immunomodulator therapy, and women with an autoimmune disease not on immunomodulator therapy, respectively (P<.001). Logistic regression analysis demonstrated higher odds of an indeterminate result for women with an autoimmune disease not on immunomodulator therapy than for controls, (adjusted odds ratio, 7.3; 95% confidence interval, 2.3-22.5). There was a negative association between women with an autoimmune disease not on immunomodulator therapy and the fetal fraction when compared with controls (aß, -2.2; 95% confidence interval, -4.2 to -0.3). CONCLUSION: Women with an autoimmune disease have lower fetal cell-free DNA fractions and higher rates of indeterminate results than women without an autoimmune disease. There was no difference in total cell-free DNA concentration. Treatment of maternal autoimmune diseases with immunomodulator therapy may decrease the indeterminate result rate.

Low fetal fraction in obese women at first trimester cell-free DNA based prenatal screening is not accompanied by differences in total cell-free DNA.

OBJECTIVE: Reasons for first trimester noninvasive prenatal screening (NIPS) test failure in obese women remain elusive. As dilution from maternal sources may be explanatory, we determined the relationship between obesity, fetal fraction (FF), and total cell-free DNA (cfDNA) using our NIPS platform. METHODS: We assessed differences in first trimester (≤14 weeks) FF, indeterminate rate, and total cfDNA between obese (n = 518) and normal-weight women (n = 237) after exclusion of confounders (anticoagulation, autoimmunity, aneuploidy) and controlling for covariates. RESULTS: Fetal fraction was lower, and the indeterminate rate higher, in obese compared to controls (9.2% ± 4.4 vs. 12.5% ± 4.5, p < 0.001 and 8.4 vs. 1.7%, p < 0.001, respectively), but total cfDNA was not different (92.0 vs. 82.1 pg/µl, p = 0.10). For each week, the FF remained lower in obese women (all p < 0.01) but did not increase across the first trimester for either group. Obesity increased the likelihood of indeterminate result (OR 6.1, 95% CI 2.5, 14.8; p < 0.001) and maternal body mass index correlated with FF (ß -0.27, 95% CI -0.3, -0.22; p < 0.001), but not with total cfDNA (ß 0.49, 95% CI -0.55, 1.53; p = 0.3). CONCLUSIONS: First trimester obese women have persistently low FF and higher indeterminate rates, without differences in total cfDNA, suggesting placental-specific mechanisms versus dilution from maternal sources as a potential etiology.