Mette Mandrup Kjær

Pregnancy after bariatric surgery – a review of benefits and risks

When other weight loss attempts have failed, bariatric surgery offers a successful alternative for obesity. Since operations are performed during womens reproductive years, the number of pregnant women with prior bariatric surgery is increasing. Bariatric surgery results in restriction of food intake and/or malabsorption leading to weight loss, but may induce a risk for malnutrition and pregnancy complications.

Antenatal management in fetal and neonatal alloimmune thrombocytopenia: A systematic review

Several strategies can be used to manage fetal or neonatal alloimmune thrombocytopenia (FNAIT) in subsequent pregnancies. Serial fetal blood sampling (FBS) and intrauterine platelet transfusions (IUPT), as well as weekly maternal IV immunoglobulin infusion (IVIG), with or without additional corticosteroid therapy, are common options, but optimal management has not been determined. The aim of this systematic review was to assess antenatal treatment strategies for FNAIT. Four randomized controlled trials and 22 nonrandomized studies were included. Pooling of results was not possible due to considerable heterogeneity. Most studies found comparable outcomes regarding the occurrence of intracranial hemorrhage, regardless of the antenatal management strategy applied; FBS, IUPT, or IVIG with or without corticosteroids. There is no consistent evidence for the value of adding steroids to IVIG. FBS or IUPT resulted in a relatively high complication rate (consisting mainly of preterm emergency cesarean section) of 11% per treated pregnancy in all studies combined. Overall, noninvasive management in pregnant mothers who have had a previous neonate with FNAIT is effective without the relatively high rate of adverse outcomes seen with invasive strategies. This systematic review suggests that first-line antenatal management in FNAIT is weekly IVIG administration, with or without the addition of corticosteroids.

Operative Complications During Pregnancy After Gastric Bypass—a Register-Based Cohort Study

BackgroundLate complications to bariatric surgery during pregnancy have become an area of concern. Expansion of the uterus and the following displacement of the small intestine may increase the risk of internal herniation. We wanted to estimate the risk and consequences of surgical complications during pregnancy in a national cohort of women with a history of gastric bypass surgery.MethodsA national, register-based cohort study of all Danish women with a history of gastric bypass surgery who had given birth from 2004 to 2010 was conducted. Surgical codes registered during pregnancy and until 120xa0days postpartum were identified in national registers, and the individual charts were reviewed in relevant cases.ResultsOf 286 women giving birth, fourteen women underwent procedures that might be related to the earlier gastric bypass surgery. Three women were operated on suspicion of internal herniation. In all three cases, mesenteric defects were found, and herniation was still present in two women, one of which died postoperatively. Five women were investigated by gastroscopy or sigmoidoscopy either during or after the delivery, and in six women cholecystectomy was performed during the puerperium.ConclusionsThe incidence of internal herniation during pregnancy was 1xa0% in our study. Internal herniation may be a serious complication in pregnant women, and both the diagnosis and treatment requires handling by experienced obstetrical, radiological, and surgical staff.

True risk of fetal/neonatal alloimmune thrombocytopenia in subsequent pregnancies: a prospective observational follow-up study

To assess neonatal platelet counts by comparing alloimmunised pregnancies from a Norwegian screening and intervention study with subsequent pregnancies from the same women.

Characterization of a Human Platelet Antigen-1a–Specific Monoclonal Antibody Derived from a B Cell from a Woman Alloimmunized in Pregnancy

Human platelet Ag (HPA)-1a, located on integrin β3, is the main target for alloantibodies responsible for fetal and neonatal alloimmune thrombocytopenia (FNAIT) in the white population. There are ongoing efforts to develop an Ab prophylaxis and therapy to prevent or treat FNAIT. In this study, an mAb specific for HPA-1a, named 26.4, was derived from an immortalized B cell from an alloimmunized woman who had an infant affected by FNAIT. It is the only HPA-1a–specific human mAb with naturally paired H and L chains. Specific binding of mAb 26.4, both native and recombinant forms, to platelets and to purified integrins αIIbβ3 (from platelets) and αVβ3 (from trophoblasts) from HPA-1a+ donors was demonstrated by flow cytometry and surface plasmon resonance technology, respectively. No binding to HPA-1a− platelets or integrins was detected. Moreover, the Ab binds with higher affinity to integrin αVβ3 compared with a second HPA-1a–specific human mAb, B2G1. Further in vitro experimentation demonstrated that mAb 26.4 can opsonize HPA-1a+ platelets for enhanced phagocytosis by monocytes, inhibit binding of maternal polyclonal anti–HPA-1a Abs, and weakly inhibit aggregation of HPA-1a–heterozygous platelets, the latter with no predicted clinical relevance. Thus, mAb 26.4 is highly specific for HPA-1a and could potentially be explored for use as a prophylactic or therapeutic reagent for FNAIT intervention and as a phenotyping reagent to identify women at risk for immunization.

The impact of gastric bypass surgery on sex hormones and menstrual cycles in premenopausal women

Abstract Obesity has adverse effects on ovulation, menstrual cyclicity and oocyte development leading to clinical symptoms such as infertility and menstrual disorders. The Roux-en-Y gastric bypass (RYGB) leads to weight loss, improved insulin sensitivity and may improve ovarian function. In 31 premenopausal women, 18 eu- and 13 oligo-/amenorrhoic, we followed the changes in follicular phase sex hormones 3, 6 and 12 month after RYGB. The average weight loss during the first postoperative year was 39.6u2009kg. The insulin sensitivity and serum insulin improved markedly especially within the first three postoperative months. SHBG increased progressively and was doubled after 12 months. In contrast, total and free androgens and DHEA declined about 50% during the first three postoperative months and remained fairly constant hereafter. One year after surgery, 85% (11/13) of the women with oligo-/amenorrhea gained regular menstrual cycles. Our results indicate that some of the endocrine changes related to regulation of ovarian function occur very early after bariatric surgery.

Anti-Human Platelet Antigen-1a Immunoglobulin G Preparation Intended to Prevent Fetal and Neonatal Alloimmune Thrombocytopenia

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a severe disease that is caused by maternal alloantibodies generated during pregnancy or at delivery as a result of incompatibility between maternal and fetal human platelet antigens (HPAs) inherited from the father. Antibody-mediated immune suppression using anti-HPA-1a immunoglobulins is thought to be able to prevent FNAIT caused by HPA-1a. A fractionation process to prepare anti-HPA-1a immunoglobulin (Ig) G (IgG) from human plasma was therefore developed. Anti-HPA-1a plasma was obtained from volunteer mothers who underwent alloimmunization against HPA-1a during a previous pregnancy. Plasma was cryoprecipitated and the supernatant treated with caprylic acid and solvent/detergent (S/D), purified by chromatography, nanofiltered, concentrated, and sterile-filtered. The anti-HPA-1a immunoglobulin fraction was characterized for purity and safety. PAK12 and quantitative monoclonal antibody immobilization of platelet antigen (MAIPA) assays were used to detect anti-HPA-1a IgG. Hepatitis C virus (HCV) removal during nanofiltration was assessed by spiking experiments, using cell culture-derived reporter HCV and luciferase analysis. The caprylic acid treatment precipitated non-Ig proteins yielding a 90% pure Ig supernatant. S-HyperCel chromatography of the S/D-treated supernatant followed by HyperCel STAR AX provided high IgG recovery (>80%) and purity (>99.5%), and efficient IgA and IgM removal. Concentrations of complement factors C3 and C4 were < 0.5 and < 0.4 mg/dL, respectively. The final IgG could be nanofiltered on Planova 20N under conditions removing more than 3 log HCV infectivity to baseline mock infection level, and concentrated to ca. 30 g/L. Proteolytic activity and thrombin generation were low in the final fraction. The Pak12 and MAIPA assays showed good recovery of anti-HPA-1a throughout the process. Clinical-grade HPA-1a IgG can be prepared using a process compliant with current quality requirements opening perspectives for the prevention of FNAIT.

Screening for fetal and neonatal alloimmune thrombocytopenia - lessons learned from a Norwegian screening program

An important issue on human platelet antigen (HPA)-1a screening has recently been addressed in Acta Obstetrica et Gynecologica Scandinavia. Winkelhorst etxa0al. reported that the vast majority of women in the general pregnant population were positive about screening (1). Here we report that there was also a positive attitude towards screening among Norwegian HPA-1a-immunized pregnant women. Further, we report that insufficient information may have led to unnecessary anxiety in this high-risk population. This article is protected by copyright. All rights reserved.

Anti-human platelet antigen (HPA)-1a antibodies may affect trophoblast functions crucial for placental development: a laboratory study using an in vitro model

BackgroundFetal and neonatal alloimmune thrombocytopenia (FNAIT) is a bleeding disorder caused by maternal antibodies against paternal human platelet antigens (HPAs) on fetal platelets. Antibodies against HPA-1a are accountable for the majority of FNAIT cases. We have previously shown that high levels of maternal anti-HPA-1a antibodies are associated with clinically significant reduced birth weight in newborn boys. Chronic inflammatory placental lesions are associated with increased risk of reduced birth weight and have previously been reported in connection with FNAIT pregnancies. The HPA-1a epitope is located on integrin β3 that is associated with integrin αIIb (the fibrinogen receptor) on platelets and megakaryocytes. Integrin β3 is also associated with integrin αV forming the αVβ3 integrin heterodimer, the vitronectin receptor, which is expressed on various cell types, including trophoblast cells. It is therefore thinkable that maternal anti-HPA-1a antibodies present during early pregnancy may affect placenta function through binding to the HPA-1a antigen epitope on invasive throphoblasts. The aim of the study was to examine whether interaction of a human anti-HPA-1a monoclonal antibody (mAb) with HPA-1a on trophoblast cells affect adhesion, migration and invasion of extravillous trophoblast cells.MethodsAn in vitro model with human anti-HPA-1a mAb, clone 26.4, and the first trimester extravillous trophoblast cell line HTR8/SVneo was employed. The xCELLigence system was utilized to assess the possible effect of anti-HPA-1a mAb on adhesion and migration of HTR8/SVneo cells. Specially designed chambers precoated with Matrigel were used to assess the effect on the invasive capacity of cells.ResultsWe found that human anti-HPA-1a mAb 26.4 partially inhibits adhesion and migratory capacity of HTR8/SVneo cells.ConclusionsOur findings suggest that anti-HPA-1a antibodies may affect trophoblast functions crucial for normal placental development. Future studies including primary throphoblast cells and polyclonal anti-HPA-1a antibodies are needed to confirm these results.

Fetal exposure to maternal human platelet antigen-1a does not induce tolerance. An analytical observational study

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a disease that may cause severe bleeding complications with risk of perinatal death or lifelong disability. The main cause of FNAIT is maternal antibodies against human platelet antigen (HPA)-1a. Both fetomaternal bleeding and transplacental trafficking of fetal cells during pregnancy could be the cause of alloimmunization. Persistence of fetal cells in the mother (fetal microchimerism) and maternal cells in the child (maternal microchimerism) are well-recognized phenomena. Thus, it could be envisaged that fetal exposure to the HPA-1a antigen could tolerize an HPA-1a negative female fetus and prevent production of anti-HPA-1a antibodies later in life if she becomes pregnant with an HPA-1a positive fetus. The objective of the current study was to assess if the risk of producing anti-HPA-1a antibodies and the severity of neonatal thrombocytopenia in HPA-1a negative women with HPA-1a positive mothers (i.e. the mother is HPA-1a/b), was lower than in HPA-1a negative women with HPA-1a negative mothers. HPA-1a negative women with HPA-1a antibodies, identified from a Norwegian screening study (1996–2004), where HPA-1 genotype of their mothers was available, were included in the study. The frequency of HPA-1a positive mothers to HPA-1a immunized daughters were compared to the calculated frequency in the general population. We did not find any difference in the frequency of HPA-1ab among mothers to daughters with HPA-1a antibodies as compared with the general population. Furthermore, acknowledging sample-size limitations, we neither found an association between the mothers’ HPA type and their daughters’ anti-HPA-1a antibody levels or any difference between the two groups of mothers (HPA-1ab vs HPA-1bb), with respect to frequency of thrombocytopenia in the children of their daughters with HPA-1a antibodies. Hence, there was no indication of tolerance against fetal HPA-1a antigen in HPA-1bb women who had been exposed to HPA-1a antigen during fetal development.