Fetal-origin cells in maternal circulation correlate with placental dysfunction, fetal sex, and severe hypertension during pregnancy.

Fetal microchimerism (FMc) arises when fetal cells enter maternal circulation, potentially persisting for decades. Increased FMc is associated with fetal growth restriction, preeclampsia, and anti-angiogenic shift in placenta-associated proteins in diabetic and normotensive term pregnancies. The two-stage model of preeclampsia postulates that placental dysfunction causes such shift in placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFLt-1), triggering maternal vascular inflammation and endothelial dysfunction. We investigated whether anti-angiogenic shift, fetal sex, fetal growth restriction, and severe maternal hypertension correlate with FMc in hypertensive disorders of pregnancy with new-onset features (n = 125). Maternal blood was drawn pre-delivery at > 25 weeks' gestation. FMc was detected by quantitative polymerase chain reaction targeting paternally inherited unique fetal alleles. PlGF and sFlt-1 were measured by immunoassay. We estimated odds ratios (ORs) by logistic regression and detection rate ratios (DRRs) by negative binomial regression. PlGF correlated negatively with FMc quantity (DRR = 0.2, p = 0.005) and female fetal sex correlated positively with FMc prevalence (OR = 5.0, p < 0.001) and quantity (DRR = 4.5, p < 0.001). Fetal growth restriction no longer correlated with increased FMc quantity after adjustment for correlates of placental dysfunction (DRR = 1.5, p = 0.272), whereas severe hypertension remained correlated with both FMc measures (OR = 5.5, p = 0.006; DRR = 6.3, p = 0.001). Our findings suggest that increased FMc is independently associated with both stages of the two-stage preeclampsia model. The association with female fetal sex has implications for microchimerism detection methodology. Future studies should target both male and female-origin FMc and focus on clarifying which placental mechanisms impact fetal cell transfer and how FMc impacts the maternal vasculature.

Poor glucose control and markers of placental dysfunction correlate with increased circulating fetal microchimerism in diabetic pregnancies.

Fetal microchimerism (FMc) arises during pregnancy as fetal cells enter maternal circulation and remain decades postpartum. Circulating FMc is increased in preeclampsia, fetal growth restriction, and as we recently showed, is associated with biomarkers of placental dysfunction in normotensive term pregnancies. Diabetes mellitus (DM) also correlates with placental dysfunction. We hypothesize that poor glucose control and markers of placental dysfunction are associated with increased circulating FMc in diabetic pregnancies. We included 122 pregnancies preceding active labor (pregestational DM, n = 77, gestational DM (GDM), n = 45) between 2001 and 2017. Maternal and fetal samples were genotyped for various human leukocyte antigen (HLA) loci, and other polymorphisms to identify fetus-specific alleles. We used validated polymerase chain reaction (PCR) assays to quantify FMc in maternal peripheral blood buffy coat. Negative binomial regression with adjustment for confounders was used to assess FMc quantity. In pregestational DM, increased circulating FMc correlated with elevation of HbA1c (≥ 6.0 %) (detection rate ratio (DRR) = 4.9, p = 0.010) and a 1000 pg/mL rise in the anti-angiogenic biomarker soluble fms-like tyrosine kinase-1 (sFlt-1) (DRR = 1.1, p = 0.011). In GDM, increased FMc correlated with elevated 2-hour oral glucose tolerance test results (DRR = 2.3, p = 0.046) and birthweight < 10th or > 90th percentile (DRR = 4.2, p = 0.049). These findings support our novel hypothesis that FMc correlates with poor glucose control and various aspects of placental dysfunction in DM. Whether increased FMc in pregnancies with poor glucose control and placental dysfunction contributes to the risk of preeclampsia in diabetic pregnancies and to the increased risk of chronic cardiovascular disease later in life remains to be investigated.

Markers of placental function correlate with prevalence and quantity of nucleated fetal cells in maternal circulation in normotensive term pregnancies.

INTRODUCTION: Transplacental fetal cell transfer results in the engraftment of fetal-origin cells in the pregnant woman's body, a phenomenon termed fetal microchimerism. Increased fetal microchimerism measured decades postpartum is implicated in maternal inflammatory disease. Understanding which factors cause increased fetal microchimerism is therefore important. During pregnancy, circulating fetal microchimerism and placental dysfunction increase with increasing gestational age, particularly towards term. Placental dysfunction is reflected by changes in circulating placenta-associated markers, specifically placental growth factor (PlGF), decreased by several 100 pg/mL, soluble fms-like tyrosine kinase-1 (sFlt-1), increased by several 1000 pg/mL, and the sFlt-1/PlGF ratio, increased by several 10 (pg/mL)/(pg/mL). We investigated whether such alterations in placenta-associated markers correlate with an increase in circulating fetal-origin cells. MATERIAL AND METHODS: We included 118 normotensive, clinically uncomplicated pregnancies (gestational age 37+1 up to 42+2 weeks' gestation) pre-delivery. PlGF and sFlt-1 (pg/mL) were measured by Elecsys® Immunoassays. We extracted DNA from maternal and fetal samples and genotyped four human leukocyte antigen loci and 17 other autosomal loci. Paternally inherited, unique fetal alleles served as polymerase chain reaction (PCR) targets for detecting fetal-origin cells in maternal buffy coat. Fetal-origin cell prevalence was assessed by logistic regression, and quantity by negative binomial regression. Statistical exposures included gestational age (weeks), PlGF (100 pg/mL), sFlt-1 (1000 pg/mL) and the sFlt-1/PlGF ratio (10 (pg/mL)/(pg/mL)). Regression models were adjusted for clinical confounders and PCR-related competing exposures. RESULTS: Gestational age was positively correlated with fetal-origin cell quantity (DRR = 2.2, P = 0.003) and PlGF was negatively correlated with fetal-origin cell prevalence (odds ratio [OR]100 = 0.6, P = 0.003) and quantity (DRR100 = 0.7, P = 0.001). The sFlt-1 and the sFlt-1/PlGF ratios were positively correlated with fetal-origin cell prevalence (OR1000 = 1.3, P = 0.014 and OR10 = 1.2, P = 0.038, respectively), but not quantity (DRR1000 = 1.1, P = 0.600; DRR10 = 1.1, P = 0.112, respectively). CONCLUSIONS: Our results suggest that placental dysfunction as evidenced by placenta-associated marker changes, may increase fetal cell transfer. The magnitudes of change tested were based on ranges in PlGF, sFlt-1 and the sFlt-1/PlGF ratio previously demonstrated in pregnancies near and post-term, lending clinical significance to our findings. Our results were statistically significant after adjusting for confounders including gestational age, supporting our novel hypothesis that underlying placental dysfunction potentially is a driver of increased fetal microchimerism.

Increased fetal microchimerism in immune and stem cell subsets in preeclampsia.

PROBLEM: Preeclampsia (PE) is associated with an increased risk of maternal cardiovascular disease (CVD), however, it is unclear whether this is due to shared underlying physiology or changes which occur during the disease process. Fetal microchimerism (FMc) within the maternal circulation can durably persist decades after pregnancy, is known to occur at greater frequency in PE, and can potentially affect local and systemic immune programming, thus changes in cellular FMc may provide a mechanism for long-term health outcomes associated with PE. METHOD OF STUDY: We investigated whether PE is associated with alterations in FMc immune and stem cell populations. We analyzed maternal peripheral blood mononuclear cells (PBMC) from PE cases (n = 16) and matched controls from normal pregnancies (n = 16), from which immune and stem cell subsets were isolated by flow cytometry. Genomic DNA was extracted from total PMBC and individual cell subsets, and FMc frequency was quantified by quantitative polymerase chain reaction assays targeting a fetal-specific non-shared polymorphism identified from family genotyping. RESULTS: There was a significant increase in FMc concentration in immune cell subsets in PE cases compared to controls, predominantly in B cell, and NK cell lymphocyte populations. There was no significant difference in FMc frequency or concentration within the stem cell population between PE and controls. CONCLUSIONS: The altered concentrations of immune cells within FMc in the maternal blood provides a potential mechanism for the inflammation which occurs during PE to induce long-lasting changes to the maternal immune system and may potentially promote chronic maternal disease.

Umbilical Cord Maternal Microchimerism in Normal and Preeclampsia Pregnancies.

Bidirectional exchange of cells between mother and fetus establishes microchimerism (Mc). Mc can persist for decades and is associated with later-life health and disease. Greater fetal Mc is detected in the maternal compartment in preeclampsia (PE), but whether maternal Mc (MMC) in umbilical cord blood (CB) is altered in PE is unknown. We evaluated MMc in CB from normal and PE pregnancies. DNA from CB mononuclear cells following placental delivery (n = 36 PE, n = 37 controls) and maternal blood was extracted and genotyped. MMc, quantified by qPCR assays targeting maternal-specific nonshared polymorphisms in CB, was compared using logistic and negative binomial regression models. Clinically and statistically relevant confounders were included, and included the total number of cell equivalents tested, gravidity, mode of delivery, birthweight, and fetal sex. PE participants delivered at earlier gestational ages, with higher Cesarean rates, and lower infant birthweights. CB MMc detection was similar between PE and controls (52.8% vs. 51.3%, respectively, p = 0.90) and unchanged after adjustment for confounders. MMc concentration was not different between groups (mean 73.7 gEq/105 gEq in PE vs. mean 22.8 gEq/105 in controls, p = 0.56), including after controlling for confounders (p = 0.64). There was no difference in CB MMc detection or concentration between PE and normal pregnancies, despite previously noted greater fetal Mc in the maternal compartment. This suggests possible differential transfer of cells at the maternal fetal interface in PE. Phenotypic evaluation of Mc cells may uncover underlying mechanisms for differential cellular exchange between mother and fetus in PE.

Cancer and Pregnancy: National Trends.

OBJECTIVE: Cancer and pregnancy are likely increasing; however, updated estimates are needed to optimally address the unique needs of this patient population. The study aims to estimate the prevalence of cancer and cancer survivorship at delivery, to test the change in odds of cancer and cancer survivorship at delivery over the 10-year period, and to compare medical conditions, serious events, and obstetric complications between pregnancies with and without cancer at delivery. STUDY DESIGN: We conducted a retrospective analysis of the National Inpatient Sample (NIS), the largest all-payer inpatient health database in the United States. We identified delivery admissions from 2004 to 2013 with a concurrent diagnosis of cancer using International Classification of Disease, ninth revision (ICD-9) codes. Multivariable logistic regression was used to test the change in prevalence of concurrent cancer, cancer survivorship, and pregnancy and to compare outcomes between deliveries with and without cancer. All analyses were adjusted for NIS-provided population weights and strata. RESULTS: During the study period, the NIS represented a national estimate of 40,855,208 deliveries. The odds of cancer increased from 3.41/10,000 deliveries in 2004 to 4.33/10,000 in 2013. This trend was statistically significant, including after adjustment for maternal age (adjusted odds ratio [aOR] = 1.03 [95% confidence interval (CI): 1.01-1.04]). Cancer survivorship at delivery increased significantly (aOR = 1.07 [95% CI: 1.06-1.08]). Women with cancer more often experienced one or more of the following: death, ventilation, cardiac arrest, sepsis, or acute respiratory or renal failure during delivery (aOR for composite outcome 10.7 [95% CI: 6.6-17.2]), even after adjustment in a multivariable logistic regression model. CONCLUSION: The odds of cancer and cancer survivorship at delivery increased from 2004 to 2013, independent of maternal age. Women with cancer were more likely to experience medical or obstetric complications during their delivery compared with women without cancer. These findings highlight the importance of obstetric and oncologic clinical and research collaboration to improve patient care. KEY POINTS: · The odds of cancer at delivery increased.. · Women with cancer may have delivery complications.. · Cancer survivorship at delivery increased..

At Preeclampsia Diagnosis, Total Cell-Free DNA Concentration is Elevated and Correlates With Disease Severity.

Background Placental derived cell-free DNA (cfDNA), widely utilized for prenatal screening, may serve as a biomarker for preeclampsia. To determine whether cfDNA parameters are altered in preeclampsia, we conducted a case-control study using prospectively collected maternal plasma (n=20 preeclampsia, n=22 normal) using our in-house validated prenatal screening assay. Methods and Results Isolated cfDNA was quantified, sequenced using Illumina NextSeq 500, and the placental-derived fraction was determined. Clinical and test characteristics were compared between preeclampsia and controls, followed by comparisons within the preeclampsia cohort dichotomized by cfDNA concentration. Lastly, cfDNA parameters in preeclampsia were correlated with markers of disease severity. Maternal age, body mass index, gestational age at delivery, cesarean rate, and neonatal birthweight were expectedly different between groups (P≤0.05). The placental-derived cfDNA fraction did not differ between groups (21.4% versus 16.9%, P=0.06); however, total cfDNA was more than 10 times higher in preeclampsia (1235 versus 106.5 pg/µL, P<0.001). This relationship persisted when controlling for important confounders (OR 1.22, 95% CI 1.04-1.43, P=0.01). The dichotomized preeclampsia group with the highest cfDNA concentration delivered earlier (33.2 versus 36.6 weeks, P=0.02) and had lower placental-derived fractions (9.1% versus 21.4%, P=0.04). Among preeclampsia cases, higher total cfDNA correlated with earlier gestational age at delivery (P=0.01) and higher maximum systolic blood pressure (P=0.04). Conclusions At diagnosis, total cfDNA is notably higher in preeclampsia, whereas the placental derived fraction remains similar to healthy pregnancies. In preeclampsia, higher total cfDNA correlates with earlier gestational age at delivery and higher systolic blood pressure. These findings may indicate increased release of cfDNA from maternal tissue injury.

Adipokine profiles in preeclampsia.

Objectives: Hypertensive disorders of pregnancy (HDP), including preeclampsia (PE), are associated with short- and long-term maternal health complications, and obesity is a leading attributable risk factor for HDP. Yet, most women identified as obese [by body mass index (BMI) ≥ 30 kg/m2] do not develop HDP, indicating limited predictability of BMI alone. In nonpregnant populations, increased visceral fat mass (VFM) is an obesity-associated phenotype increasing the risk of developing hypertension. We sought to assess whether, in pregnancy, obese women with PE would have higher circulating levels of adipokines preferential to VFM compared to obese women without PE.Study Design: We performed a case-control study of women with and without PE, including obese (n = 65; BMI ≥ 30 kg/m2) and normal weight (n = 52; BMI 18.4-24.9 kg/m2) women. Plasma concentrations of adipokines preferential to VFM (visfatin, resistin), adipokines reflecting overall adiposity (leptin, adiponectin), and inflammatory cytokines were compared.Results: We found that among obese women, cases had significantly higher levels of VFM-associated adipokines and cytokines compared to controls [visfatin (p < .01, t = -3.8), resistin (p = .002, t = 1.12), IFN gamma (p = .04, t = -2.0), IL-6 (p < .01, t = -2.65), IL1-beta (p < .01, t = -4.1), IL-2 (p < .01, t = -3.9)]. Interestingly, however, obese and normal weight cases had similar VFM-adipokine and cytokine levels [visfatin (p = .34, t = -0.35), resistin (p = .55, t = -0.25)], and inflammatory marker concentrations [IFN gamma (p = .86, t = -0.76), IL-6 (p = .91, t = -0.53), IL-1beta (p = .67, t = 1.18), and IL-2 (p = .45, t = -1.16)]. These data possibly suggest an association between VFM and PE that is present independent of BMI.Conclusion: In summary, we demonstrated that, in normal-weight and obese women, PE was associated with higher concentrations of VFM-preferential adipokines compared to normal-weight and obese controls without PE.

Obstetric Outcomes in Young Women with Breast Cancer: Prior, Postpartum, and Subsequent Pregnancies.

OBJECTIVE: This study aimed to describe obstetric outcomes in a large cohort of young women with breast cancer, considering the chronological relationship of pregnancies with breast cancer diagnosis. STUDY DESIGN: From a population-based cohort study of young women with breast cancer from 2004 to 2010, we conducted secondary interviews to obtain detailed obstetric histories. Pregnancies were categorized based on timing of breast cancer diagnosis: prior, postpartum, and subsequent pregnancies after breast cancer diagnosis. A generalized estimated equation model was used to account for correlated data. RESULTS: In this cohort (n = 366), median age at breast cancer diagnosis was 40.1 years, and 84.7% were Caucasian. Tumor type was notable for 25.1% triple negative, and 56.1% had Stage I disease. There were 922 prior pregnancies, 21 with postpartum diagnosis of breast cancer, and 24 pregnancies subsequent to breast cancer diagnosis. Non-live birth outcomes occurred significantly more often in the postpartum group (p-value: 0.001) compared with the other groups, which had higher live birth rates, after adjustment for maternal age, parity, body mass index, and race. CONCLUSION: Overall, pregnancy outcomes before and after breast cancer diagnosis are reassuring.

Temperature-Responsive Magnetic Nanoparticles for Enabling Affinity Separation of Extracellular Vesicles.

Small magnetic nanoparticles that have surfaces decorated with stimuli-responsive polymers can be reversibly aggregated via a stimulus, such as temperature, to enable efficient and rapid biomarker separation. To fully realize the potential of these particles, the synthesis needs to be highly reproducible and scalable to large quantity. We have developed a new synthesis for temperature-responsive magnetic nanoparticles via an in situ co-precipitation process of Fe2+/Fe3+ salts at room temperature with poly(acrylic acid)- block-poly( N-isopropylacrylamide) diblock co-polymer template, synthesized via the reversible addition-fragmentation chain-transfer polymerization method. These particles were 56% polymer by weight with a 6.5:1 Fe/COOH ratio and demonstrated remarkable stability over a 2 month period. The hydrodynamic diameter remained constant at ∼28 nm with a consistent transition temperature of 34 °C, and the magnetic particle separation efficiency at 40 °C was ≥95% over the 2 month span. These properties were maintained for all large-scale synthesis batches. To demonstrate the practical utility of the stimuli-responsive magnetic nanoparticles, the particles were incorporated into a temperature-responsive binary reagent system and efficiently separated a model protein biomarker (mouse IgG) as well as purified extracellular vesicles derived from a human biofluid, seminal plasma. The ease of using these particles will prove beneficial for various biomedical applications.

Cardiomyopathy and Preeclampsia.

BACKGROUND: Preeclampsia is associated with diastolic dysfunction, peripartum cardiomyopathy, and both pre-existing and subsequent maternal cardiovascular disease. Gene mutations causing idiopathic cardiomyopathy were recently implicated in peripartum cardiomyopathy. We sought to determine whether cardiomyopathy gene mutations are also a contributory factor in preeclampsia. METHODS: Subjects were participants in The Preeclampsia Registry and Biobank. After providing informed consent, subjects with a history of preeclampsia completed a detailed questionnaire and provided medical records for diagnostic confirmation. Saliva samples were collected for DNA isolation. Whole exome sequencing was performed to detect rare variants (minor allele frequency of <0.1%) in 43 genes associated with cardiomyopathy. Missense variants were deemed damaging missense if so classified by any of 7 standard function prediction algorithms. Variants were defined as loss-of-function if they caused a stop-gain, splicing, or frame-shift insertion or deletion. Results were compared with data from 2 control groups: unrelated women with a gynecologic disorder sequenced using the same methods and instruments (n=530) as well as published variant data from 33 000 subjects in the Exome Aggregation Consortium. Preeclampsia was not excluded in control groups. RESULTS: Of 181 subjects with confirmed preeclampsia, 96% were white. Seventy-two percent had ≥1 preterm preeclampsia delivery <37 weeks. Among preeclampsia subjects, whole exome sequencing demonstrated 10 rare loss-of-function variants and 228 rare damaging missense variants in the 43 cardiomyopathy genes considered. The prevalence of these loss-of-function variants was significantly higher in preeclampsia subjects (5.5%) compared with the local control (2.5%) population ( P=0.014). Sixty-eight percent of women with preeclampsia carried ≥1 loss-of-function or damaging missense variant (mean of 1.94 mutations). As seen with peripartum cardiomyopathy, most mutations (55%) were found in the TTN gene. Seventy-three percent of preeclampsia subjects had TTN mutations in the preeclampsia cohort versus 48% in local controls ( P=1.36E-11). DISCUSSION: Women who develop preeclampsia are more likely to carry protein-altering mutations in genes associated with cardiomyopathy, particularly in TTN. Mutations promoting cardiomyopathy are prevalent in preeclampsia, idiopathic cardiomyopathy, and peripartum cardiomyopathy, and they are important risk factors for a widening spectrum of cardiovascular disorders. Detecting these variants should allow more specific diagnosis, classification, counseling, and management of women at risk.

Preeclampsia and scleroderma: a prospective nationwide analysis.

INTRODUCTION: In a preliminary case-control study, women with scleroderma more frequently reported having had hypertensive complications during pregnancy compared with healthy women. MATERIAL AND METHODS: To prospectively investigate this possible association, we conducted a nation-wide cohort analysis of a major hypertensive complication during pregnancy, namely preeclampsia, and later scleroderma. Analyses were based on Danish register-based birth and hospital contact data on preeclampsia and scleroderma. We followed 778,758 women from time of giving birth between 1978 and 2010 to end of follow-up, emigration, death, or scleroderma diagnosis, whichever occurred first. The association was evaluated by incidence rate ratios, obtained in Poisson regression models. RESULTS: We report that preeclampsia is associated with a 69% significantly increased risk of later developing scleroderma. CONCLUSIONS: Though these findings do not impact clinical care directly, the association of preeclampsia with scleroderma underscores the significant relation of preeclampsia and other adverse pregnancy outcomes with later disease in women and should be included in patient counseling and education.

Maternal microchimerism is prevalent in cord blood in memory T cells and other cell subsets, and persists post-transplant.

Among reported advantages of umbilical cord blood (CB) in transplantation is lower leukemia relapse probability. Underlying cellular mechanisms of graft-vs.-leukemia (GVL) are thought to include a prominent role for T cells. Cells of the CB's mother, maternal microchimerism (MMc), were recently strongly, but indirectly, implicated in this GVL benefit. We assayed MMc directly and hypothesized benefit accrues from CB maternal T cells. MMc was quantified in 51 CBs and, within memory T, naïve T, B, NK cells, and monocytes in 27 CBs. Polymorphism-specific quantitative-PCR assays targeted maternal genotypes non-shared with CBs. Overall MMc was common and often at substantial levels. It was present in 52.9% of CB and in 33.3-55.6% of tested subsets. Remarkably, MMc quantities were greater in memory T cells than other subsets (p < 0.001). Expressed as genome equivalents (gEq) per 105 total gEq tested (gEq/105), memory T cell MMc averaged 850.2 gEq/105, while other subset mean quantities were 13.8-30.1 gEq/105. After adjustment for proportionality in CB, MMc remained 6-17 times greater in memory T, and 3-9 times greater in naïve T, vs. non-T-cell subsets. Further, CB-origin MMc was detected in vivo in a patient up to 6 mo post-transplantation, including among T cells. Overall, results revealed levels and phenotypes of CB MMc with potential relevance to CB transplantation and, more broadly, to offspring health.

Characterization of the HLA-DRß1 third hypervariable region amino acid sequence according to charge and parental inheritance in systemic sclerosis.

BACKGROUND: Specific HLA class II alleles are associated with systemic sclerosis (SSc) risk, clinical characteristics, and autoantibodies. HLA nomenclature initially developed with antibodies as typing reagents defining DRB1 allele groups. However, alleles from different DRB1 allele groups encode the same third hypervariable region (3rd HVR) sequence, the primary T-cell recognition site, and 3rd HVR charge differences can affect interactions with T cells. We considered 3rd HVR sequences (amino acids 67-74) irrespective of the allele group and analyzed parental inheritance considered according to the 3rd HVR charge, comparing SSc patients with controls. METHODS: In total, 306 families (121 SSc and 185 controls) were HLA genotyped and parental HLA-haplotype origin was determined. Analysis was conducted according to DRß1 3rd HVR sequence, charge, and parental inheritance. RESULTS: The distribution of 3rd HVR sequences differed in SSc patients versus controls (p = 0.007), primarily due to an increase of specific DRB1*11 alleles, in accord with previous observations. The 3rd HVR sequences were next analyzed according to charge and parental inheritance. Paternal transmission of DRB1 alleles encoding a +2 charge 3rd HVR was significantly reduced in SSc patients compared with maternal transmission (p = 0.0003, corrected for analysis of four charge categories p = 0.001). To a lesser extent, paternal transmission was increased when charge was 0 (p = 0.021, corrected for multiple comparisons p = 0.084). In contrast, paternal versus maternal inheritance was similar in controls. CONCLUSIONS: SSc patients differed from controls when DRB1 alleles were categorized according to 3rd HVR sequences. Skewed parental inheritance was observed in SSc patients but not in controls when the DRß1 3rd HVR was considered according to charge. These observations suggest that epigenetic modulation of HLA merits investigation in SSc.

Statistical Methods for Unusual Count Data: Examples From Studies of Microchimerism.

Natural acquisition of small amounts of foreign cells or DNA, referred to as microchimerism, occurs primarily through maternal-fetal exchange during pregnancy. Microchimerism can persist long-term and has been associated with both beneficial and adverse human health outcomes. Quantitative microchimerism data present challenges for statistical analysis, including a skewed distribution, excess zero values, and occasional large values. Methods for comparing microchimerism levels across groups while controlling for covariates are not well established. We compared statistical models for quantitative microchimerism values, applied to simulated data sets and 2 observed data sets, to make recommendations for analytic practice. Modeling the level of quantitative microchimerism as a rate via Poisson or negative binomial model with the rate of detection defined as a count of microchimerism genome equivalents per total cell equivalents tested utilizes all available data and facilitates a comparison of rates between groups. We found that both the marginalized zero-inflated Poisson model and the negative binomial model can provide unbiased and consistent estimates of the overall association of exposure or study group with microchimerism detection rates. The negative binomial model remains the more accessible of these 2 approaches; thus, we conclude that the negative binomial model may be most appropriate for analyzing quantitative microchimerism data.

Slc20a2 deficiency results in fetal growth restriction and placental calcification associated with thickened basement membranes and novel CD13 and lamininα1 expressing cells.

The essential nutrient phosphorus must be taken up by the mammalian embryo during gestation. The mechanism(s) and key proteins responsible for maternal to fetal phosphate transport have not been identified. Established parameters for placental phosphate transport match those of the type III phosphate transporters, Slc20a1 and Slc20a2. Both members are expressed in human placenta, and their altered expression is linked to preeclampsia. In this study, we tested the hypothesis that Slc20a2 is required for placental function. Indeed, complete deficiency of Slc20a2 in either the maternal or embryonic placental compartment results in fetal growth restriction. We found that Slc20a2 null mice can reproduce, but are subviable; ∼50% are lost prior to weaning age. We also observed that 23% of Slc20a2 deficient females develop pregnancy complications at full term, with tremors and placental abnormalities including abnormal vascular structure, increased basement membrane deposition, abundant calcification, and accumulation of novel CD13 and lamininα1 positive cells. Together these data support that Slc20a2 deficiency impacts both maternal and neonatal health, and Slc20a2 is required for normal placental function. In humans, decreased levels of placental Slc20a1 and Slc20a2 have been correlated with early onset preeclampsia, a disorder that can manifest from placental dysfunction. In addition, preterm placental calcification has been associated with poor pregnancy outcomes. We surveyed placental calcification in human preeclamptic placenta samples, and detected basement membrane-associated placental calcification as well as a comparable lamininα1 positive cell type, indicating that similar mechanisms may underlie both human and mouse placental calcification.

Uterine rupture risk after periviable cesarean delivery.

OBJECTIVE: To investigate the risk of uterine rupture in women with prior periviable cesarean delivery and prior term cesarean delivery independent of initial incision type. METHODS: We conducted a retrospective longitudinal cohort study using Washington state birth certificate data and hospital discharge records, identifying primary cesarean deliveries performed at 20-26 weeks and 37-41 weeks of gestation with subsequent delivery between 1989 and 2008. We compared subsequent uterine rupture risk in the two groups considering both primary incision type and subsequent labor induction and augmentation. RESULTS: We identified 456 women with index periviable cesarean delivery and 10,505 women with index term cesarean delivery. Women with index periviable cesarean delivery were younger, more frequently of nonwhite race, more likely to smoke, and more likely to have hypertension. Women in the periviable group had more index classical incisions (42% compared with 1%, P<.001) and fewer subsequent inductions and augmentations (8% compared with 16%, P<.001). Uterine rupture in the subsequent pregnancy occurred more frequently among women in the index periviable group than those in the index term group (8/456 [1.8%] compared with 38/10,505 [0.4%], odds ratio [OR] 4.9, 95% confidence interval [CI] 2.3-10.6). This relationship persisted among women with a low transverse incision (4/228 [1.8%] compared with 36/9,558 [0.4%], OR 4.7, 95% CI 1.7-13.4). CONCLUSION: Cesarean delivery at periviability compared with term is associated with an increased risk for uterine rupture in a subsequent pregnancy, even after low transverse incision. These data support judicious use of cesarean delivery at periviable gestational ages and inform subsequent counseling. LEVEL OF EVIDENCE: II.

Copy-number variation and false positive prenatal aneuploidy screening results.

Investigations of noninvasive prenatal screening for aneuploidy by analysis of circulating cell-free DNA (cfDNA) have shown high sensitivity and specificity in both high-risk and low-risk cohorts. However, the overall low incidence of aneuploidy limits the positive predictive value of these tests. Currently, the causes of false positive results are poorly understood. We investigated four pregnancies with discordant prenatal test results and found in two cases that maternal duplications on chromosome 18 were the likely cause of the discordant results. Modeling based on population-level copy-number variation supports the possibility that some false positive results of noninvasive prenatal screening may be attributable to large maternal copy-number variants. (Funded by the National Institutes of Health and others.).