Fetal fraction of cell-free DNA in pregnancies after fresh or frozen embryo transfer following assisted reproductive technologies.

STUDY QUESTION: Is the fetal fraction (FF) of circulating cell-free DNA (cfDNA) affected in pregnancies following ART treatment with either fresh or frozen embryo transfer (ET) compared with natural conception? SUMMARY ANSWER: This study shows a significant reduction in the FF in ART patients compared with naturally conceived pregnancies, which seems to be more pronounced after fresh ET compared with frozen ET. WHAT IS KNOWN ALREADY: Non-invasive prenatal testing (NIPT) is based on cfDNA in maternal blood, of which about 10% is of placental origin and thus represents the fetal karyotype. Validation studies have demonstrated a high sensitivity, specificity and positive predictive value of NIPT for the detection of fetal trisomy 21, 18 and 13. Nevertheless, the FF of cfDNA is an important factor for NIPT test accuracy. Several studies have found a reduction in FF for pregnancies following ART in comparison with natural conception. However, knowledge on how the FF is affected in ART pregnancies after fresh ET compared with frozen ET is very limited. STUDY DESIGN, SIZE, DURATION: The study was designed as a case-control study. A total of 54 women with an ongoing pregnancy following ART treatment were included. After exclusion for different reasons, statistical analyses were based on 23 NIPT samples from pregnant women treated with fresh ET and 26 NIPT samples from pregnant women treated with frozen-thawed ET in a modified natural cycle. Women were included between February 2018 and November 2018. The results were compared with a control group of 238 naturally conceived pregnancies with a high-risk result from the combined first trimester screening (cFTS). PARTICIPANTS/MATERIALS, SETTING, METHODS: The study included women from the Fertility Clinics at Copenhagen University Hospital Hvidovre and Copenhagen University Hospital Rigshospitalet. Blood samples for NIPT analysis were drawn between 11 + 0 and 14 + 2 weeks of gestation and were all analyzed at the NIPT Center at Copenhagen University Hospital Hvidovre. The NIPT-test was performed by massive-parallel whole-genome sequencing. The FF was determined using the SeqFF algorithm. MAIN RESULTS AND THE ROLE OF CHANCE: We found a reduction in FF in ART patients compared with naturally conceived pregnancies, and the reduction was more pronounced for ART pregnancies after fresh ET (mean FF = 0.049) compared with frozen ET (mean FF = 0.063) (multivariate analysis adjusted for maternal BMI, P = 0.02). Another multivariate analysis, adjusted for BMI and multiples of median (MoM) values for pregnancy-associated plasma protein-A (PAPP-A), demonstrated a significantly reduced FF for ART pregnancies (mean FF = 0.056) compared with naturally conceived pregnancies (mean FF = 0.072) (P < 0.0001). We found that FF was significantly reduced with increasing maternal BMI (P < 0.0001) and with decreasing MoM values of PAPP-A (P = 0.003). LIMITATIONS, REASONS FOR CAUTION: A limitation of our study design was the relatively small sample size. Another limitation was that the control group was not matched with the ART-treated women. The majority of the women from the control group had a high risk from cFTS, thereby their biochemical markers were diverging. However, the biochemical markers for the ART-treated women with fresh or frozen ET were not divergent within the subgroups. WIDER IMPLICATIONS OF THE FINDINGS: Concurrent with other studies demonstrating a reduced FF for singleton pregnancies after ART treatment compared with naturally conceived pregnancies, we found a reduction in FF between the two groups. This is one of the first studies to examine FF in ART pregnancies after fresh ET compared with frozen ET, hence the existing knowledge is limited. We find that FF is even more reduced in pregnancies following fresh ET compared with frozen ET, which might possibly reflect the predisposition of being small for gestational age after fresh ET compared with natural cycle frozen ET. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by the A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal (the A.P. Møller Foundation for General Purposes). All authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER: NA.

Noninvasive prenatal testing and maternal obesity: A review.

Noninvasive prenatal testing (NIPT) has become a popular screening test for the most common fetal aneuploidies. The performance of NIPT is affected by several factors including maternal obesity, which results in a greater rate of no-calls for obese pregnant women. Guidelines regarding NIPT in prenatal screening have been published, but with few and divergent recommendations on the issue. We aimed to review the medical literature, guidelines from scientific societies and information material from commercial NIPT providers on no-calls and maternal obesity. We systematically identified medical literature and guidelines from scientific societies using the database MEDLINE. Information material from commercial NIPT providers was found via a systematic search on Google.com. Nine medical studies investigating the association between maternal obesity and NIPT no-calls were included. They all showed the same trend: increasing no-call rate with increasing maternal obesity. The no-call rate ranged from 0% to 4.2% for women with body mass index (BMI) 18.5-24.9 and from 5.4% to 70.1% for women BMI ≥40. We identified 17 scientific societies with guidelines and 13 commercial NIPT providers. All were checked for information material on no-calls and maternal obesity. To allow comparison, all guidelines were examined to answer the same three predefined questions. Of the 17 included scientific societies, 13 (76.5%) mentioned the association between maternal obesity and NIPT no-calls, two (11.8%) specified weight limits and three (17.6%) advised against NIPT for severely obese pregnant women. None of the 13 commercial NIPT providers provided specific recommendations, but four (30.8%) cite maternal obesity as a potential cause for a no-call. Because of the increasing number of patients in this group, we advocate updated recommendations to guide decision making in prenatal screening for obese pregnant women.

Prediction of Preeclampsia in Nulliparous Women according to First Trimester Maternal Factors and Serum Markers.

OBJECTIVE: To evaluate the performance of maternal risk factors (BMI and mean arterial pressure [MAP]) and first-trimester maternal serum markers in the early prediction of preeclampsia (PE) in nulliparous women. MATERIAL AND METHODS: This was a case-cohort study based on a cohort of 14,207 nulliparous women. A total of 213 cases with term PE (from 37 weeks + 0 days) and 55 cases with preterm PE (before 37 weeks + 0 days) were identified and validated. Randomly, 449 controls were selected. Serum samples previously collected for the double test (pregnancy-associated plasma protein A [PAPP-A] and free ß human chorionic gonadotrophin [hCGß]) as part of the first-trimester screening program were retrieved and analyzed for placental growth factor (PlGF), soluble fms-like tyrosine kinase 1 (sFlt-1), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and neutrophil gelatinase-associated lipocalin (NGAL). Concentrations were transformed to multiples of the median (MoM). Multivariate regression analysis was used for prediction models. Receiver-operating characteristics (ROC) curves were used for evaluation of the screening performance. RESULTS: In preterm PE, the PlGF (0.79 MoM), sFlt-1 (0.86 MoM), NGAL (1.15 MoM), and PAPP-A (0.89 MoM) medians were significantly altered. In term PE, PlGF (0.90 MoM) and NT-proBNP (0.86 MoM) medians were significantly reduced. The combination of MAP and PlGF yielded a 39% detection rate of preterm PE for a 10% false-positive rate. The combination of MAP, BMI, and PlGF yielded a 33% detection rate of term PE with a 10% false-positive rate. CONCLUSION: First-trimester MAP, maternal serum PlGF, and NGAL are markers of preterm PE. Maternal serum sFlt-1 is a significant marker of preterm PE, but only early in the first trimester. First-trimester maternal serum NT-proBNP is not a predictor of PE. Screening performance for PE with these markers individually or in combination is modest.

Serum anti-Müllerian hormone concentration before and after salpingectomy for ectopic pregnancy.

RESEARCH QUESTION: Does salpingectomy for ectopic pregnancy affect the ovarian reserve measured by changes in pre- and post-operative levels of anti-Müllerian hormone (AMH)? DESIGN: This is a prospective observational multicentre study of 64 women treated with salpingectomy for an ectopic pregnancy. AMH was measured in serum samples collected at admission before salpingectomy and at follow-up (median time to follow-up [interquartile range] was 3 [3-4] months). Changes in serum AMH levels were investigated using Wilcoxon signed-rank test and the relationship between changes in AMH and age, time to follow-up, and pre-operative serum AMH level was investigated using linear regression analysis. The biological variation of AMH was also calculated. RESULTS: Serum AMH levels did not differ significantly before and after salpingectomy (median ∆AMH [follow-up value minus admission value] 0.40 pmol/l, interquartile range -2.0 to 4.0 pmol/l). ΔAMH was independent of age, time to follow-up and pre-operative serum AMH level. The intra-individual biological variation for AMH ranged from 12.1% to 26.3%, depending on time between the two samples. CONCLUSIONS: This is the first paired study to investigate serum AMH values before and after salpingectomy in an unselected population of women presenting with an ectopic pregnancy, including both patients who conceived naturally and following fertility treatment. It was found that salpingectomy for ectopic pregnancy had no short-term effect on serum AMH levels, and changes in AMH levels were independent of age, time to follow-up, and pre-operative serum AMH level. Furthermore, the study demonstrated a 6-month biological variation of AMH of less than 30%.

Affinity purification of native glycodelin from amniotic fluid for biological investigations and development of a glycodelin ELISA for clinical studies.

INTRODUCTION: Glycodelin is a glycoprotein with different oligosaccharides that are responsible for its diverse biological functions in contraception and immunosuppression. Therefore, it is necessary to have access to adequate amounts of glycodelin with retained carbohydrate structure for functional studies because the carbohydrate part can be lacking or be insufficient in recombinant glycodelin from prokaryotic and eukaryotic cell systems. METHODS AND RESULTS: Native glycodelin was purified from amniotic fluid by a series of affinity chromatography steps and had many glycosylated forms verified by mass spectrometry. About 7.5 mg glycodelin was obtained from 1.5 L amniotic fluid. No high molecular mass forms of glycodelin were found in amniotic fluid. Aliquots of the purified glycodelin were used as an immunogen in rabbits for antibody production against glycodelin and a calibrator in a highly sensitive glycodelin enzyme-linked immunosorbent assay (ELISA) with a detection limit of about 1 µg/L. CONCLUSIONS: Native glycodelin was purified from amniotic fluid and used as an immunogen for raising a rabbit antibody against glycodelin and a calibrator in a highly sensitive glycodelin ELISA. We found no high molecular mass forms of glycodelin in amniotic fluid. Aliquots of the purified glycodelin were set aside for functional studies which are in progress.

Discordant non-invasive prenatal testing (NIPT) - a systematic review.

With a high sensitivity and specificity, non-invasive prenatal testing (NIPT) is an incomparable screening test for fetal aneuploidy. However, the method is rather newly introduced, and experiences with discordant results are few. We did a systematic review of literature reporting details of false positive and false negative NIPT results. Discordant sex chromosome results were not included. We identified 22 studies reporting case details. In total, 206 discordant cases were included, of which 88% were false positive and 12% false negative. Details on maternal age, gestational age, platform/company, Z-score, fetal fraction, results and explanation were specified. The main reasons for discordant results were confined placental mosaicism, maternal copy number variation, vanished twin, maternal cancer and true fetal mosaicism. A very high percentage of cases (67%) were reported with no obvious biological or technical explanation for the discordant result. The included cases represent only a minor part of the true number of false positive or false negative NIPT cases identified in fetal medicine clinics around the world. To ensure knowledge exchange and transparency of NIPT between laboratories, we suggest a systematic recording of discordant NIPT results, as well as a quality assurance by external quality control and accreditation. © 2017 John Wiley & Sons, Ltd.

Investigation on the ability of first trimester glycodelin and angiopoietin-2 to predict small-for-gestational age pregnancies at delivery.

BACKGROUND: The aim was to investigate whether first trimester glycodelin and angiopoietin-2 can predict small-for-gestational age (SGA) at delivery, individually or in combination. METHODS: In this case-control study we measured glycodelin and angiopoietin-2 on serum from 170 singleton pregnant women delivering SGA neonates and 985 singleton pregnant women delivering normal-weighted neonates. All values were converted to multiples of the medians (MoM). RESULTS: Pregnant women delivering SGA neonates had lower first trimester glycodelin and angiopoietin-2 MoM values [median (interquartile range)] compared with pregnant women delivering normal-weighted neonates for glycodelin: 0.86 (0.58-1.24) vs. 1.03 (0.74-1.45), p<0.001, and for angiopoietin-2: 0.89 (0.69-1.19) vs. 1.01 (0.78-1.31), p<0.001. The prediction performances of the biomarkers showed that the areas under the curve (AUC) were 0.59 (glycodelin), 0.58 (angiopoietin-2), and 0.60 (glycodelin and angiopoietin-2). CONCLUSIONS: We demonstrated that first trimester glycodelin and angiopoietin-2 were associated with SGA, but they were, individually and in combination, poor predictors of SGA at delivery. The AUCs were low which indicate low detection rates and high false positive rates.

First trimester PAPP-A2, PAPP-A and hCGß in small-for-gestational-age pregnancies.

BACKGROUND: Pregnancy-associated plasma protein-A2 (PAPP-A2) is a recently discovered protease that cleaves a subset of insulin-like growth factor binding proteins (IGFBP). The molecular function suggests its involvement in the IGF system that is vital for fetal growth and development. Our objectives were to establish first trimester median curves of PAPP-A2, PAPP-A and hCGß for singleton normal pregnancies and to investigate whether an altered level of one or more of the biomarkers is associated with small-for-gestational-age (SGA) neonates before and after stratification according to maternal hypertension and/or proteinuria. METHODS: This was a case-control study based on 985 pregnant women delivering normal-weighted neonates and 170 pregnant women delivering SGA neonates. PAPP-A2 was measured by ELISA. PAPP-A and hCGß were measured by an automatic analyzer. Median curves from 8+1 to 14+0 were established and all concentration values were converted to multiples of the median (MoM) values. RESULTS: Before stratification the SGA cases had unaffected PAPP-A2 MoM and hCGß MoM levels but lower PAPP-A MoM compared with normal controls. After stratification the SGA normotensive subgroup had lower PAPP-A2 MoM and PAPP-A MoM levels than the normal normotensive subgroup. Severe preeclamptic women delivering SGA neonates had higher PAPP-A2 MoM compared to the normotensive women delivering SGA neonates. CONCLUSIONS: Pregnant women delivering SGA neonates did not have altered levels of PAPP-A2 or hCGß but had lower PAPP-A level in the first trimester compared with pregnant women delivering normal-weighted neonates. Pregnancies complicated with severe preeclampsia and SGA may be associated with high PAPP-A2 level.

The maternal age-related first trimester risks for trisomy 21, 18 and 13 based on Danish first trimester data from 2005 to 2014.

OBJECTIVES: Most currently used age-related risks of T21, T18 and T13 are based on estimates of the live-birth prevalence, and describe an exponential increase of risk by increased maternal age. We investigated the first trimester prevalence of T21, T18 and T13 in a large population of Danish women. METHODS: From the Danish Cytogenetic Central Registry we got the information of all pre- and postnatally diagnosed fetuses with T21, T18 or T13 between 2005 and 2014 in Denmark. Information on the total number of births and maternal age at birth were gathered from StatBank Denmark. RESULTS: The total number of included women was 605 853. The total number of T21 cases was 1564, T18 cases was 401 and T13 cases was 157. The overall first trimester prevalence per 10 000 pregnancies was 25.8 for T21, 6.6 for T18 and 2.6 for T13. Boltzmann sigmoidal model (Y = Bottom + (top-bottom / (1 - exp (V50 - X) / slope)) was found to best describe the age-related risk of T21, T18 and T13. CONCLUSION: We found that the age-related risks are better described by sigmoidal functions, contrary to the widely assumed exponential functions. Our results indicate a lower age-related a priori risk of T21, T18 and T13 compared to widely used risk models. © 2016 John Wiley & Sons, Ltd.

Mining of hospital laboratory information systems: a model study defining age- and gender-specific reference intervals and trajectories for plasma creatinine in a pediatric population.

BACKGROUND: The knowledge of physiological fluctuation and variation of even commonly used biochemical quantities in extreme age groups and during development is sparse. This challenges the clinical interpretation and utility of laboratory tests in these age groups. To explore the utility of hospital laboratory data as a source of information, we analyzed enzymatic plasma creatinine as a model analyte in two large pediatric hospital samples. METHODS: Plasma creatinine measurements from 9700 children aged 0-18 years were obtained from hospital laboratory databases and partitioned into high-resolution gender- and age-groups. Normal probability plots were used to deduce parameters of the normal distributions from healthy creatinine values in the mixed hospital datasets. Furthermore, temporal trajectories were generated from repeated measurements to examine developmental patterns in periods of changing creatinine levels. RESULTS: Creatinine shows great age dependence from birth throughout childhood. We computed and replicated 95% reference intervals in narrow gender and age bins and showed them to be comparable to those determined in healthy population studies. We identified pronounced transitions in creatinine levels at different time points after birth and around the early teens, which challenges the establishment and usefulness of reference intervals in those age groups. CONCLUSIONS: The study documents that hospital laboratory data may inform on the developmental aspects of creatinine, on periods with pronounced heterogeneity and valid reference intervals. Furthermore, part of the heterogeneity in creatinine distribution is likely due to differences in biological and chronological age of children and should be considered when using age-specific reference intervals.

First trimester pregnancy-associated plasma protein A and human chorionic gonadotropin-beta in early and late pre-eclampsia.

BACKGROUND: The aim of this study was to compare pregnancy-associated plasma protein A (PAPP-A) and the ß-subunit of human chorionic gonadotropin (hCGß) measured in maternal plasma at the first trimester screening, in women who later developed early or late pre-eclampsia (PE) to women with normal pregnancies. METHODS: In the study were included 161 cases with PE and 88 controls with uncomplicated pregnancies. Plasma PAPP-A and hCGß were measured between gestational age (GA) 8+2 and 14+0, and cases with early and late onset PE were compared with controls. RESULTS: Median of hCGß (MoM) was lower in women with early (p<0.05) and late PE (p<0.05) compared to healthy pregnant women. Median (range) of hCGß (MoM) for women with early onset PE, late onset PE, and women with healthy pregnancies, were 0.75 (0.30-1.21), 0.93 (0.26-3.18), and 0.97 (0.33-4.12), respectively. No significant difference in the median of PAPP-A (MoM) was found between the groups. CONCLUSIONS: hCGß was significantly lower in pregnancies that subsequently developed PE and might be of use in the effort of trying to find ways to predict PE. No significant difference was found for PAPP-A in our study.

Are there characteristics of the false-negative cases from the first trimester combined screening programme for Down syndrome?

PURPOSE OF REVIEW: To review if there are any characteristics of false-negative cases from the first trimester combined screening programme for Down syndrome and by that to stimulate new approaches for improvements of the screening performance. RECENT FINDINGS: We are aware of only two studies based on screening results of false-negative cases. Screening results from false-negative cases show that maternal age is lower, nuchal translucency smaller, pregnancy-associated plasma protein-A level higher, ß-human chorionic gonadotropin level lower and crown-rump length bigger than among true positive cases. Around 50% of false-negative cases had a final risk between 1 : 300 and 1 : 1000. There might also be a difference in maternal smoking status, conception method, ethnicity and weight discrepancy between false-negative and true positive cases. New biomarkers and secondary sonographic markers may also characterize false-negative cases, but investigations on these subjects have not been done so far. Finally, we think that the organization of a screening programme in all its details is a very important factor when it comes to optimizing screening performance. SUMMARY: Screening parameters of false-negative cases tend toward the values of unaffected pregnancies with lower maternal age, smaller nuchal translucency, higher pregnancy-associated plasma protein-A level, lower ß-human chorionic gonadotropin level and bigger crown-rump length than among true positive cases.

Recent progress in the utility of anti-Müllerian hormone in female infertility.

PURPOSE OF REVIEW: To discuss the recent developments in the utility of anti-Müllerian hormone (AMH) in the context of female infertility. RECENT FINDINGS: AMH measurements have entered the clinical practice in counseling of women before in-vitro fertilization (IVF) treatment. AMH measurements can predict both poor and hyperresponse, and can enable clinicians to individualize the treatment strategies. In natural conception, AMH is a good predictor of age at menopause, but it is unclear whether AMH correlates with the fecund ability in the normal population. AMH has also proven its utility in the assessment of ovarian damage due to gonadotoxic treatment or ovarian surgery. Lastly, AMH might assist in the initial diagnosis of oligomenorrhea or amenorrhea, as high levels of AMH are suggestive of polycystic ovarian syndrome and seem to correlate with the severity of the syndrome. SUMMARY: AMH is a glycoprotein secreted by the granulosa cells of small growing follicles and indirectly reflects the primordial follicle pool. The ovaries contain a limited number of primordial follicles and their depletion marks the menopause. Thus, the remaining primordial follicle pool is referred to as the ovarian reserve. The clearest data for the clinical utility of AMH is in the context of IVF. The support for other indications is weaker, but rapidly increasing.

Autocorrelation and cross-correlation between hCGß and PAPP-A in repeated sampling during first trimester of pregnancy.

BACKGROUND: Theoretically, repeated sampling of free ß-human chorionic gonadotropin (hCGß) and pregnancy associated plasma protein-A (PAPP-A) in the first trimester of pregnancy might improve performance of risk assessment of trisomy 21 (T21). To assess the performance of a screening test involving repeated measures of biochemical markers, correlations between markers must be estimated. The aims of this study were to calculate the autocorrelation and cross-correlation between hCGß and PAPP-A in the first trimester of pregnancy and to investigate the possible impact of gestational age at the first sample and time between sampling on the correlation. METHODS: A prospective study was conducted including 3891 unaffected singleton pregnancies. Two measurements of hCGß and PAPP-A were obtained during the first trimester in each pregnancy. Correlations between the four parameters, hCGß first, hCGß second, PAPP-A first and PAPP-A second, were estimated and presented in terms of Pearson's r coefficients. Furthermore, the correlation between paired samples as a function of time between samples was investigated. RESULTS: The study demonstrated high correlation between first and second samples of hCGß and PAPP-A with a correlation coefficient of 0.80 and 0.79, respectively. By contrast, the correlations between hCGß and PAPP-A were low. In addition, the study demonstrated that the correlation between paired samples of hCGß and PAPP-A decreases with earlier gestational age at the first sample and with increasing time between samples. CONCLUSIONS: We have developed a parameter set in terms of correlations between biochemical markers, which can be incorporated into a T21 screening algorithm based on repeated measures within the first trimester.

Anti-Müllerian hormone levels in salpingectomized compared with nonsalpingectomized women with tubal factor infertility and women with unexplained infertility.

OBJECTIVE: To investigate the consequence of salpingectomy on ovarian reserve by measuring anti-Müllerian hormone (AMH) levels before in vitro fertilization (IVF) treatment in salpingectomized women compared with nonsalpingectomized women with tubal factor infertility, women with unexplained infertility and fertile control women, and to evaluate whether AMH levels could predict IVF outcome. DESIGN: Cross-sectional study extended from a previous prospective study. SETTING: Four university fertility clinics. PATIENTS: Seventy-one women with infertility and 21 fertile controls. INTERVENTIONS: Blood sampling and IVF and embryo transfer in the following cycle. MAIN OUTCOME MEASURE: Serum AMH levels and oocytes retrieved. RESULTS: Anti-Müllerian hormone levels were significantly lower in the salpingectomy infertility group (median 16.1, range 5.2-54 pmol/L) compared with the nonsalpingectomy tubal factor infertility group (median 23.4, range 3.5-50 pmol/L; p = 0.04). In all groups, AMH levels correlated positively with the number of oocytes retrieved. AMH predicted poor response (five or fewer oocytes) with a sensitivity and specificity of 90% and 70%, at a 19 pmol/L cut-off value. CONCLUSION: Serum AMH levels were lower in salpingectomized women compared with women with tubal factor infertility and preserved Fallopian tubes, indicating that ovarian reserve might be affected by tubal surgery. Furthermore, serum AMH levels could predict a poor oocyte response (five or fewer oocytes) in the study group of infertile women.

The role of anti-Müllerian hormone in female fertility and infertility - an overview.

Anti-Müllerian hormone (AMH) plasma levels reflect the continuous non-cyclic growth of small follicles, thereby mirroring the size of the resting primordial follicle pool and thus acting as a useful marker of ovarian reserve. Anti-Müllerian hormone seems to be the best endocrine marker for assessing the age-related decline of the ovarian pool in healthy women; thus, it has a potential ability to predict future reproductive lifespan. The most established role for AMH measurements is before in vitro fertilization is initiated, because AMH can be predictive of the ovarian response, namely poor and hyper-responses. However, recent research has also highlighted the use of AMH in a variety of ovarian pathological conditions, including polycystic ovary syndrome, granulosa cell tumors and premature ovarian failure. A new commercial enzyme-linked immunosorbent assay for measuring AMH levels has been developed, making results from different studies more comparable. Nevertheless, widespread clinical application awaits an international standard for AMH, so that results using future assays can be reliably compared.

First-trimester risk calculation for trisomy 13, 18, and 21: comparison of the screening efficiency between 2 locally developed programs and commercial software.

BACKGROUND: Reliable individual risk calculation for trisomy (T) 13, 18, and 21 in first-trimester screening depends on good estimates of the medians for fetal nuchal translucency thickness (NT), free ß-subunit of human chorionic gonadotropin (hCGß), and pregnancy-associated plasma protein-A (PAPP-A) in maternal plasma from unaffected pregnancies. Means and SDs of these parameters in unaffected and affected pregnancies are used in the risk calculation program. Unfortunately, our commercial program for risk calculation (Astraia) did not allow use of local medians. We developed 2 alternative risk calculation programs to assess whether the screening efficacies for T13, T18, and T21 could be improved by using our locally estimated medians. METHODS: We established these estimates from 19 594 women with singleton pregnancies and from 100 pregnant women carrying a fetus affected with trisomy (11 with T13, 23 with T18, and 66 with T21). All measured values were recalculated to a multiple of the median (MoM) and log(10) transformed; the mean and SD were calculated for each group. RESULTS: At a given risk cutoff value, we observed a slight improvement in detection rate (DR) for T13, T18, and T21 for a slightly higher false-positive rate (FPR) compared with the commercial program. The lower FPR in the commercial program was caused mainly by an inaccuracy in the PAPP-A median. CONCLUSIONS: Center-specific medians for NT, hCGß, and PAPP-A should be used in risk calculation programs to ensure high DRs and low FPRs for all 3 trisomies at a given risk cutoff.

Biological variation of free ß chorionic gonadotropin and pregnancy-associated plasma protein A in first trimester pregnancies.

BACKGROUND: Trisomy 21 risk estimation in first trimester pregnancies can be performed by a combined test based on ultrasound measurement of fetal nuchal translucency thickness and maternal plasma concentrations of free ß human chorionic gonadotropin (hCGß) and pregnancy-associated plasma protein A (PAPP-A). However, little knowledge exists regarding the biological variation of hCGß and PAPP-A when the time interval between sampling increases. METHODS: We estimated these variations from double measurements of hCGß and PAPP-A in first trimester pregnancies in 167 women. Data were divided into three groups based on the number of days between sampling. The correlation coefficients and biological variation were estimated for each group. RESULTS: The correlation coefficient between the first and second samples was 0.841 for hCGß, and 0.706 for PAPP-A. The ranges for biological variation were 11.9%-48.5% for hCGß and 31.6%-63.3% for PAPP-A, increasing with time between sampling. The average overall biological variation for hCGß was 29%, and 49.7% for PAPP-A. CONCLUSIONS: We found high biological variation for plasma concentrations of hCGß and PAPP-A, increasing with longer time intervals between sampling. From our data that showed high correlation of hCGß and PAPP-A in the first and second sample, we found no reason to recommend retesting. However, new studies should clarify whether PAPP-A should be collected early, and hCGß late, in the first trimester of pregnancy.