Maternal serum CA 19-9 and CA 15-3 levels in pregnancies affected by trisomy 21.

OBJECTIVES: To investigate the levels of tumour markers CA 19-9 and CA 15-3 in the first trimester maternal serum of euploid control and trisomy 21 pregnancies. METHODS: Maternal serum marker levels of 69 trisomy 21 and 388 euploid controls were quantified by the Kryptor analyser, and levels were compared between the two groups after analysis for confounding factors. Monte Carlo simulation was carried out to determine the effect of adding potential markers to the combined test. RESULTS: Neither marker was affected by gestational age; however, CA 19-9 required correction for maternal weight. CA 19-9 was significantly increased in trisomy 21 pregnancies (0.98 MoM in euploid, 1.16 MoM in trisomy 21, p = 0.024). Levels of CA 15-3 were not found to differ significantly (1.03 MoM in euploid, 1.09 in trisomy 21, p = 0.130). Detection rates were unaffected by addition of CA 19-9 to the combined test. CONCLUSION: Although a small significant increase in CA 19-9 levels was found in trisomy 21 group, it is unlikely to be of any use as part of a trisomy 21 screening tool.

A comparison of two immunoassay methods for the measurement of maternal serum placental growth factor in early pregnancy.

OBJECTIVES: To compare the DELFIA Xpress and Quantikine ELISA placental growth factor (PlGF) immunoassay platforms by analysing the same set of early first-trimester maternal serum samples from cases with trisomy 21 and euploid controls. METHODS: Thirty-seven trisomy 21 cases and 243 euploid control serum samples, drawn at 8(+0) to 10(+6) weeks of gestation, were reanalysed by Quantikine PlGF ELISA following original analysis on the DELFIA Xpress platform. RESULTS: PlGF levels increased with gestation in the euploid controls when measured on both platforms, although raw levels were in general lower on the DELFIA Xpress. After conversion to multiples of the median (MoMs), PlGF was increased in trisomy 21 cases when measured on the DELFIA Xpress platform (euploid: 1.00 MoM, trisomy 21: 1.32 MoM, p < 0.0001) but unchanged when measured on the Quantikine ELISA (euploid: 1.01 MoM, trisomy 21: 1.06 MoM, p = 0.84). CONCLUSIONS: Discrepancies exist in the measurement of PlGF when performed on these different platforms, which may to some extent contribute to the inconsistencies found in the literature with regard to PlGF in trisomy 21 pregnancies.

Maternal serum placental growth factor in second trimester trisomy 21 pregnancies.

OBJECTIVE: To investigate the levels of placental growth factor (PlGF) in second trimester maternal serum in trisomy 21 cases and euploid controls - an unclear subject in the published literature. METHODS: Second trimester maternal serum samples from 17 recent (since 2005) and 74 older trisomy 21 cases and 542 euploid controls were extracted from frozen storage and retrospectively analysed for PlGF using a DELFIA Xpress immunoassay platform. Results were converted to multiples of median (MoM) for comparison. RESULTS: The control group had a PlGF MoM of 0.99, the recent trisomy 21 cases had a PlGF MoM of 1.13 and the older cases a PlGF MoM of 1.11; however, the differences between trisomy 21 cases and controls were not significant. CONCLUSION: Although we have found no significant change in the second trimester levels of PlGF in trisomy 21 pregnancies, there remains wide disagreement within the literature on the behaviour of this marker during pregnancies of this syndrome.

Stability of first trimester placental growth factor in serum and whole blood.

BACKGROUND: Placental growth factor (PlGF) is a proposed first-trimester screening marker for pre-eclampsia. This study investigates the stability of PlGF in serum and whole blood at typical routine storage temperatures. METHODS: Serum pools were stored at refrigerator temperature, room temperature or 30 °C for up to 30 days, or exposed to up to six freeze-thaw cycles. Whole blood was stored at room temperature or 30 °C for up to 6 days. PlGF was quantified using a DELFIA Xpress analyser. RESULTS: Placental growth factor levels increased over time, seemingly because of the dissociation of PlGF bound to a soluble binding protein, sFlt-1. Increase was slow in serum at refrigerator temperature, remaining stable (less than 10% change from start point) for at least 30 days. At room temperature PlGF was stable for 3.3 days and at 30 °C for 1 day. Serum PlGF remained stable for at least six freeze-thaw cycles. In whole blood, instability was worse, being stable for only 19.4 h at room temperature and just 3.3 h at 30 °C. CONCLUSION: Routine screening of sample handling requires careful monitoring. However, no extra precautions need to be taken when PlGF is used for pre-eclampsia screening run alongside existing first trimester aneuploidy screening programs that include hCGß.

PP13 as a marker of pre-eclampsia: A two platform comparison study.

OBJECTIVE: To evaluate the role of PP13 as a marker for pre-eclampsia (PE) by comparing two different immunoassay platforms. METHODS: In this case-control study, first-trimester serum samples from 195 normal pregnancies and 37 pregnancies with PE were analysed for PP13 by using a manual DTL ELISA and the AutoDELFIA(®) platform. RESULTS: Levels of PP13 in first-trimester pregnancies increased with gestational age in controls and pre-eclampsia cases using both methods of analysis, but at different rates. PP13 levels were decreased in women with PE. Levels of the marker are found to be more reduced in PE cases when measured using the DTL ELISA compared to AutoDELFIA(®). CONCLUSION: Further studies are needed to compare the performance of the DTL ELISA and the AutoDELFIA(®) PP13 assays in terms of reproducibility, robustness and clinical performance in predicting pre-eclampsia.

Early first-trimester maternal serum placental growth factor in trisomy 21 pregnancies.

OBJECTIVES: To measure maternal serum placental growth factor (PlGF) levels in trisomy 21 cases and controls in samples drawn before 11 weeks' gestation. METHODS: Early first-trimester maternal serum samples, drawn between 8 + 0 and 10 + 6 weeks' gestation, for 37 trisomy 21 cases and 244 unaffected controls were retrieved from frozen storage, and PlGF was retrospectively measured using a DELFIA Xpress immunoassay platform. PlGF levels were converted to multiples of the median (MoM), and trisomy 21 and unaffected groups were compared. RESULTS: Raw PlGF and MoM levels were significantly higher in the maternal serum of trisomy 21 cases than in controls over the 3-week gestational window (unaffected 1.0 MoM compared with trisomy 21 1.3 MoM (P < 0.0001)). However at 8 completed weeks of gestation the increase was most significant and at 10 completed weeks there was no significant difference between trisomy 21 and unaffected PlGF levels. CONCLUSIONS: Early PlGF levels in maternal serum in trisomy 21 cases may be increased relative to unaffected controls, however, the relationship between PlGF levels and gestational age in trisomy 21 and unaffected pregnancies in the first two trimesters of pregnancy appears to be complex and requires further study.

A re-evaluation of the influence of maternal insulin-dependent diabetes on fetal nuchal translucency thickness and first-trimester maternal serum biochemical markers of aneuploidy.

OBJECTIVE: To evaluate the influence of maternal insulin-dependent diabetes mellitus (IDDM) on maternal serum free ß-hCG, pregnancy-associated plasma protein-A (PAPP-A) and fetal nuchal translucency (NT) thickness from 11 weeks to 13 weeks 6 days of gestation in a large cohort of women screened prospectively for chromosomal anomalies. METHODS: Information on maternal IDDM status, maternal serum biochemical marker levels and fetal NT were collected from the prenatal screening computer records. On total, the control group included 83,972 and the IDDM group included 489 pregnancies. The median-corrected free ß-hCG and PAPP-A, expressed as MoM, and fetal NT, expressed as delta values, in the IDDM and non-IDDM groups were compared. RESULTS: There were no significant differences between the IDDM and non-IDDM groups in median-corrected free ß-hCG (IDDM 1.01 MoM, non-IDDM 1.01 MoM; p = 0.970), or mean delta NT (IDDM 0.00 mm, non-IDDM 0.02 mm; p = 0.412). However, the median-corrected PAPP-A was significantly lower (IDDM 0.88 MoM, non-IDDM 1.03 MoM; p < 0.0001). CONCLUSIONS: In pregnancies with maternal IDDM, first-trimester screening for chromosomal defects does not require adjustments for the measured fetal NT and maternal serum free ß-hCG. However, for PAPP-A the 15% reduction is large enough to require correction in the calculation of risks for chromosomal defects.

ADAM-12 stability in first trimester maternal serum.

BACKGROUND: Maternal serum A Disintergrin And Metaloprotease-12 (ADAM-12) has been proposed as a marker for prenatal screening of chromosomal abnormalities, pre-eclampsia and other adverse pregnancy outcomes. In this study, we examine the stability of ADAM-12 with time and at different temperatures. METHODS: Maternal serum and whole blood pools were stored at 30 degrees C, room temperature and refrigerator temperature or subjected to repeated freeze-thaw cycles. ADAM-12 was measured at set time points using an automated DELFIA research assay. RESULTS: Using a 10% change in concentration as a limit of stability, ADAM-12 is stable in serum for less than 15 h at 30 degrees C, less than 20 h at room temperature and for 51 h at refrigerator temperature. ADAM-12 levels are not altered following three - 20 degrees C to room temperature freeze-thaw cycles. The stability of ADAM-12 in whole blood appears similar to that in serum. CONCLUSIONS: The findings of this study suggest that ADAM-12 may be unstable under many routine laboratory conditions, and the marker's instability may also be partly responsible for the discrepancies in the literature.

First-trimester placental growth factor as a marker for hypertensive disorders and SGA.

OBJECTIVE: The objective of this study was to examine first-trimester maternal serum placental growth factor (PlGF) levels in pregnancies which later develop hypertensive and growth complications. METHODS: In this case-control study, PlGF levels were measured by AutoDELFIA immunoassay platform. There were 47 cases of at least one of the following adverse outcomes: pre-eclampsia (PE), small for gestational age (SGA), haemolysis elevated liver enzymes and low platelets (HELLP) and gestational hypertension (GH) and 452 matched controls. RESULTS: PlGF levels were significantly lower in cases of all PE, early PE, HELLP, all SGA, early SGA and SGA without PE, but not in GH, late PE, late SGA, PE with SGA or PE without SGA or HELLP. CONCLUSION: Low levels of first-trimester PlGF provide a good indicator of SGA complications and some hypertensive disorders, in particular severe cases of PE such as early onset and HELLP syndrome.

PP13 stability in first trimester maternal serum and whole blood.

BACKGROUND: Maternal serum placental protein 13 (PP13) has been proposed as a marker for prenatal screening of pre-eclampsia (PE) and other adverse pregnancy outcomes. This study aims to examine the stability of PP13 at different routine temperatures. METHODS: Maternal serum pools and whole blood samples were stored at '30 degrees C', room temperature or refrigerator temperature. Further, serum pools were also subjected to repeated freeze-thaw cycles. PP13 was measured at set time points using an AutoDELFIA research assay. RESULTS: Levels of PP13 are stable, defined as less than 10% change in concentration, in serum for 17.4 h at '30 degrees C', 3.4 days at room temperature and for at least 34 days at refrigerator temperature. PP13 concentration is not altered following three -20 degrees C to room temperature freeze-thaw cycles. PP13 is stable in whole blood for at least 3 days at all three temperatures studied. CONCLUSIONS: PP13 is a suitably stable molecule and can be treated under routine laboratory and normal transport temperatures.

First trimester maternal serum placental growth factor in trisomy 21 pregnancies.

OBJECTIVE: To examine placental growth factor (PlGF) levels in first trimester maternal serum in trisomy 21 pregnancies and to investigate the potential value of PlGF in a first trimester screening test. METHODS: First trimester maternal serum from 70 trisomy 21 cases and 375 euploid controls were retrospectively analyzed for PlGF using a DELFIA Xpress immunoassay platform. Results were expressed as multiples of medians (MoM) for comparison. RESULTS: PlGF levels were significantly decreased in pregnancies with trisomy 21, 0.76 MoM versus 0.98 MoM in controls. Inclusion of PlGF into the first trimester combined test [maternal age, pregnancy associated plasma protein-A (PAPP-A), free-beta human chorionic gonadotrophin (beta-hCG) and nuchal translucency] would increase the detection rate by 0.5% at a 5% false positive rate. CONCLUSION: PlGF at 11 weeks to 13 weeks 6 days has the potential to be included as a marker for the detection of pregnancies with trisomy 21.

Maternal serum ADAM-12 as a potential marker for different adverse pregnancy outcomes.

OBJECTIVE: To investigate first-trimester ADAM-12 levels in pregnancies which later develop hypertensive and growth complications. METHODS: First-trimester serum samples (11(+0) to 13(+6) weeks) were retrieved from frozen storage. 47 samples with at least one of the following adverse outcomes: pre-eclampsia (PE), small for gestational age, HELLP syndrome and gestational hypertension were analysed and 452 controls matched to the cases by gestational age and length of storage were analysed. ADAM-12 levels were measured by the automated AutoDELFIA immunoassay platform. RESULTS: ADAM-12 was found to increase with gestational age (11(+0) to 13(+6) weeks) and decrease with increasing maternal weight and in women who smoked. After correction, ADAM-12 median multiples of the median were increased in cases with HELLP syndrome, all PE and PE only. CONCLUSION: The increased first-trimester levels of ADAM-12 in PE and HELLP are in contrast with previous findings. The usefulness of ADAM-12 as a marker for adverse outcomes is still unclear.

First-trimester markers for the prediction of pre-eclampsia in women with a-priori high risk.

OBJECTIVE: To investigate the predictive value of the combination of first-trimester serum placental protein 13 (PP13), uterine artery Doppler pulsatility index (PI) and pulse wave analysis (augmentation index at a heart rate of 75 beats per min (AIx-75)), and to evaluate concurrent and contingent strategies using this combination for assessing the risk of pre-eclampsia in high-risk women. METHODS: In this nested case-control study, serum PP13, uterine artery mean PI and AIx-75 were measured at between 11 + 0 and 13 + 6 weeks' gestation in women at increased risk of pre-eclampsia. For each case of pre-eclampsia (n = 42), five matched controls were randomly selected from the study group. Gestation specific multiples of the median (MoMs) were adjusted for body mass index, ethnicity, smoking, age and parity. MoMs were compared between cases and controls using the Wilcoxon rank sum test. Sensitivities and specificities were derived from receiver-operating characteristics curves. RESULTS: Compared with controls, women who developed pre-eclampsia had lower PP13, higher uterine artery mean PI and higher AIx-75 (P < 0.001). For a 10% false-positive rate, the best detection rate for pre-eclampsia (85.7% (95% CI, 71.5-94.6%)) and pre-eclampsia requiring delivery before 34 weeks (92.9% (95% CI, 66.1-99.8%)) was achieved by concurrent testing with all three markers. The best contingency screening sequences for pre-eclampsia were (AIx-75 --> PP13 --> mean PI) and (PP13 --> AIx-75 --> mean PI), with an 86% detection rate for false-positive rates of 9 and 10%, respectively. These two sequences would require 410 and 414 tests, respectively, compared with 756 tests in concurrent testing. CONCLUSION: Combination of first-trimester PP13, uterine artery mean PI and pulse-wave analysis is promising for the prediction of pre-eclampsia in women at increased a-priori risk and may be useful in clinical practice. Contingency screening achieved similar detection rates to concurrent testing, but required almost 50% fewer tests, making it a more cost-effective option.

Maternal serum inhibin-A and activin-A levels in the first trimester of pregnancies developing pre-eclampsia.

OBJECTIVE: To evaluate whether measurement of maternal serum inhibin-A and activin-A at 11 + 0 to 13 + 6 weeks of gestation, alone or in combination with second-trimester uterine artery pulsatility measured by Doppler velocimetry, is useful in predicting those women who will develop pre-eclampsia. METHODS: This was a nested case-control study of pre-eclampsia cases with controls matched for gestational age and storage time for the maternal serum. Samples were collected as part of a first-trimester prenatal chromosomal anomaly screening program. Activin-A and inhibin-A were measured using a commercial enzyme-linked immunosorbent assay and the clinical outcomes were blinded to the operator. All the patients underwent uterine artery Doppler flow velocimetry to measure the mean pulsatility index at 22-24 weeks' gestation. RESULTS: In total there were 64 cases with pre-eclampsia, with 34 delivering prior to 35 weeks of gestation. The control group included 240 cases. In the control group the levels of activin-A and inhibin-A did not change across the narrow gestational window and the median levels were 2.16 ng/mL and 231.13 pg/mL, respectively. In the pre-eclamptic group levels of activin-A and inhibin-A were significantly increased, at 2.52 ng/mL and 286.64 pg/mL (1.24 multiples of the median (MoM) and 1.17 MoM, respectively). There was no difference in the median MoM in those delivering prior to 35 weeks and those delivering later. At cut-offs of the 90(th) centile of normal, activin-A and inhibin-A levels would have identified 20% and 35%, respectively, of cases that would develop pre-eclampsia. When combined with uterine artery Doppler, activin-A measurement could have increased the detection rate from 55% to 63% and inhibin-A measurement could have increased it to 68% at a 5% false positive rate. CONCLUSION: Although increased in the first trimester, levels of activin-A and inhibin-A are probably too low to make a significant contribution to screening for pre-eclampsia at this time.

First-trimester ultrasound and biochemical markers of aneuploidy and the prediction of preterm or early preterm delivery.

OBJECTIVES: To examine the clinical utility of the first-trimester markers of aneuploidy in their ability to predict preterm delivery. METHODS: We examined 54 722 singleton pregnancies with no chromosomal abnormality and with complete outcome data that had undergone screening for trisomy 21 by a combination of fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 and 13 + 6 weeks' gestation. The biochemical markers were converted to multiples of the median (MoM) of the expected normal median for a pregnancy of the same gestation and the measurements of fetal NT were expressed as the difference (delta) from the normal median NT for crown-rump length. The association between free beta-hCG, PAPP-A and delta NT and the incidence of preterm delivery before 37 weeks or early preterm delivery before 34 weeks was assessed by comparing the relative incidence at a number of MoM or delta NT cut-offs and at various centile cut-offs. At various marker levels the likelihood ratios (LR) for preterm delivery and early preterm delivery were also calculated after excluding other adverse pregnancy complications. RESULTS: The risk of preterm delivery increased with decreasing maternal serum PAPP-A. In the 3132 cases delivering before 37 weeks the PAPP-A MoM was 0.91 and in the 1060 cases delivering before 34 weeks the PAPP-A MoM was 0.90. At the 5th centile of the normal outcome group for PAPP-A (0.415 MoM) the odds ratios for delivery before 37 weeks and before 34 weeks were 1.92 and 2.35, respectively. The respective values for the 5th centile of free beta-hCG (0.41 MoM) were 1.18 and 1.08 and for the 95th centile of delta NT they were 0.91 and 0.77, respectively. CONCLUSIONS: Low levels of maternal serum PAPP-A are associated, in the absence of an abnormal karyotype, with an increased risk of preterm or early preterm delivery. The LR profiles provided at various levels of PAPP-A may be of some help in counseling women with such results and may raise awareness among healthcare professionals for increased surveillance in such cases.

First-trimester biochemical markers of aneuploidy and the prediction of small-for-gestational age fetuses.

OBJECTIVES: To examine the clinical utility of the first-trimester biochemical markers of aneuploidy in their ability to predict subsequent delivery of a small-for-gestational age (SGA) infant. METHODS: We examined singleton pregnancies with no chromosomal abnormality and with complete outcome data that had undergone screening for trisomy 21 by a combination of fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 and 13 + 6 weeks' gestation. The biochemical markers were converted to multiples of the expected normal median (MoM) for a pregnancy of the same gestation. The association between free beta-hCG and PAPP-A and the incidence of SGA were assessed by comparing the relative incidence at MoM cut-offs and birth-weight centile cut-offs. At various marker levels the likelihood ratios (LR) for SGA were also calculated after excluding other adverse pregnancy complications. RESULTS: There were 46,262 pregnancies resulting in live births with birth weight at or above the 10(th) centile, and 3,539 below the 10(th) centile for gestation (SGA). There was a significant inverse association between the risk for SGA and maternal serum PAPP-A MoM but not free beta-hCG MoM. At the 5(th) centile of the normal outcome group for PAPP-A (0.415 MoM) the odds ratios for SGA below the 10(th), 5(th) and 3(rd) centiles of normal were 2.70, 3.21 and 3.66 and the respective detection rates for SGA were 12.0%, 14.0% and 16.0%. CONCLUSIONS: Low levels of maternal serum PAPP-A are associated, in the absence of an abnormal karyotype, with an increased risk for subsequent delivery of an SGA infant.

First-trimester maternal serum PP-13, PAPP-A and second-trimester uterine artery Doppler pulsatility index as markers of pre-eclampsia.

OBJECTIVE: To evaluate whether measurement of maternal serum placental protein-13 (PP-13) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks of gestation alone or in combination with second-trimester uterine artery pulsitility measured by Doppler velocimetry is useful in predicting those women who will develop pre-eclampsia METHODS: This was a nested case-control study of pre-eclampsia cases with controls matched for gestational age and storage time for the maternal serum. Samples were collected as part of a first-trimester prenatal chromosomal anomaly screening program and were routinely tested for PAPP-A. PP-13 was tested using an enzyme linked immunosorbent assay (ELISA) by an examiner who was blinded to pregnancy outcome. All patients also underwent uterine artery Doppler flow velocimetry to measure the mean pulsatility index (PI) at 22-24 weeks' gestation. RESULTS: There were 446 controls and 44 cases with early pre-eclampsia where delivery was induced prior to 35 weeks. In addition there were a further 44 cases with pre-eclampsia in which delivery was not induced before term. Median PP-13 levels for controls, all cases and early pre-eclampsia cases were 176.9, 121.9 and 111.7 pg/mL, with multiples of the median (MoMs) of 1.00, 0.69 and 0.63, respectively (P < 0.001). PAPP-A MoMs were 1.00, 0.89 (P = 0.076) and 0.89 (P = 0.042) and mean PIs were 1.0, 1.6 (P < 0.001) and 1.7 (P < 0.001) for controls, all cases and early cases, respectively. Receiver-operating characteristics (ROC) curve analysis for either all cases or early cases vs. controls yielded areas under the curve for PP-13, PAPP-A and PI respectively of 0.68 (95% CI, 0.61-0.74; P < 0.001), 0.56 (95% CI, 0.49-0.63; P = 0.076) and 0.79 (95% CI, 0.72-0.87; P < 0.001) for all cases and 0.71 (95% CI, 0.63-0.79; P < 0.001), 0.59 (95% CI, 0.51-0.68; P = 0.076) and 0.86 (95% CI, 0.77-0.94; P < 0.001) for early cases. At a specificity set to 0.80 the sensitivities were 0.50, 0.23 and 0.76 for PP-13, PAPP-A and PI in the early cases and 0.44, 0.24 and 0.73 in all cases. Combining PP-13 and PI using logistic regression analysis yielded an area under the curve of 0.84 (95% CI, 0.78-0.90; P < 0.001) and a sensitivity of 0.74 in all cases, and 0.90 (95% CI, 0.84-0.96; P < 0.001) and a sensitivity of 0.79 for early cases. PAPP-A with PI gave an area under the curve of 0.82 (95% CI, 0.76-0.90; P < 0.001) and a sensitivity of 0.76 in all cases. Combining PAPP-A with PP-13 and PI did not add significantly to the sensitivity. CONCLUSION: First-trimester PP-13 levels may be useful in predicting pre-eclampsia and early pre-eclampsia, and the accuracy of the method increases when coupled with second-trimester Doppler PI measurement. First-trimester PAPP-A provides some prediction for pre-eclamspia when combined with PI but does not add to the prediction of early pre-eclampsia when PP-13 and PI are used together. Further studies are required to establish the real value of PP-13 in first-trimester screening for pre-eclampsia.

First-trimester ultrasound and biochemical markers of aneuploidy and the prediction of impending fetal death.

OBJECTIVES: To examine the clinical utility of the first-trimester markers of aneuploidy in their ability to predict future fetal loss. METHODS: We examined 54,722 singleton pregnancies with no chromosomal abnormality and with complete outcome data that had undergone screening for trisomy 21 by a combination of fetal nuchal translucency (NT) thickness, maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 and 13 + 6 weeks' gestation. The biochemical markers were converted to multiples of the expected normal median for a pregnancy of the same gestation (MoM) and the measurements of fetal NT were expressed as the difference (delta) from the normal median NT for crown-rump length (CRL). The association between free beta-hCG, PAPP-A and delta NT and the incidence of fetal loss prior to 24 weeks, at or after 24 weeks or at any time, was assessed by comparing the relative incidence at a number of MoM or delta NT cut-offs and at various centile cut-offs. At various marker levels the likelihood ratio (LR) for fetal loss was also calculated. RESULTS: The rate of fetal loss increased with decreasing maternal serum free beta-hCG and PAPP-A and increasing delta NT. At the 5th centile of the normal outcome group for free beta-hCG (0.41 MoM) the odds ratio for fetal loss before 24 weeks, at or above 24 weeks and at any gestation was 3.1, 1.8 and 2.6, respectively. The respective values for the 5th centile of PAPP-A (0.415 MoM) were 3.3, 1.9 and 2.8 and for the 95th centile of delta NT they were 2.5, 1.9 and 2.2, respectively. There was almost no correlation between reduced levels (

First and second-trimester biochemical markers of chromosomal anomalies and their relationship to maternal haemoglobin levels.

OBJECTIVE: To evaluate a previous hypothesis that maternal serum biochemical markers used in the assessment of Down syndrome risk are related to maternal haemoglobin concentrations. METHODS: A series of 1306 second-trimester prenatal screening records were retrieved including information on marker levels (AFP and fbetahCG MoMs), Down's risk, a priori age risk, maternal weight and maternal height. Each individual record was merged with data from haematological investigations on samples collected on the same day. A similar series of 1688 first-trimester screening records were also retrieved including the maker levels for PAPP-A, and fbetahCG MoMs were merged with data from haematological investigations carried out on the same day. The two groups were categorised according to their haemoglobin levels; anaemic (less than 11.0 g/dL in first trimester and 10.5 g/dL in the second trimester), high haemoglobin (greater than 14.0 g/dL and 13.2 g/dL) or normal (between these ranges). An analysis was made of marker levels in the various groups before and after correction for ethnicity and of the screen-positive rate in the various groups. Using a formula based on maternal height and weight, variation of marker levels with plasma volume was assessed. RESULTS: In the first trimester, 12.6% of the pregnant population was anaemic and 1.6% had elevated haemoglobin levels. In the second trimester this was 12.7 and 3.9%. These figures varied considerably with ethnic origin, with Asian and Afro-Caribbean women being more anaemic than Caucasian women. Haemoglobin levels declined by 7% between the 11- and 21-week period. Maternal plasma volume (as calculated by a widely used maternal height and weight relationship) was not correlated with weight-corrected biochemical marker MoMs in either trimester. A weak but significant correlation of maternal plasma volume and haemoglobin concentration was observed. There was no significant correlation between biochemical marker MoMs and haemoglobin concentration. Although the proportion of pregnancies designated screen positive decreased as haemoglobin levels increased, this was paralleled by a decrease in the maternal age a priori risk. CONCLUSIONS: There is no relationship between maternal haemoglobin levels and the levels of Down syndrome markers in either the first or second trimester. Biochemical marker levels do not need to be corrected for haemoglobin concentrations when used in screening for Down syndrome.