Maternal serum beta-HCG and alpha-fetoprotein concentrations in singleton pregnancies following assisted reproduction

The impact of fresh versus frozen-thawed embryos on maternal serum analyte levels in IVF singleton and twin pregnancies

PURPOSE

To determine whether embryo cryopreservation is associated with a difference in maternal serum analyte levels in singleton and twin pregnancies conceived via in vitro fertilization (IVF).

METHODS

This was a retrospective cohort study of singleton and twin pregnancies conceived via IVF from a university health system from 01/2014 to 09/2019. Patients with available first and second trimester serum analyte data were included and analyzed separately. Multiple of the median (MoM) values for free β-human chorionic gonadotropin (β-hCG), pregnancy-associated plasma protein A, alpha-fetoprotein (AFP), Inhibin A, and unconjugated estriol (uE3) were compared between two groups: pregnancies conceived after the transfer of fresh embryos versus pregnancies conceived after the transfer of frozen-thawed embryos. Multiple linear regression of log MoM values with F test was performed to adjust for potential confounders.

RESULTS

For singletons, fresh embryos were associated with a lower median first trimester free β-hCG (1.00 MoM vs. 1.14 MoM; parameter estimate [PE] 0.90, 95% CI 0.82-0.99, p = .03) compared to frozen-thawed embryos. Fresh embryos were also associated with a lower median second trimester uE3 (0.93 MoM vs. 1.05 MoM; PE 0.88, CI 0.83-0.95, p = .0004) and AFP (1.02 MoM vs. 1.19 MoM; PE 0.91, CI 0.84-0.99, p = .02) compared to frozen-thawed embryos in singletons. There were no significant differences between median first and second trimester serum analytes in twin pregnancies compared between the two groups.

CONCLUSION

Singleton pregnancies derived from fresh embryos had lower first (free β-hCG) and second (uE3 and AFP) trimester analytes compared to frozen-thawed embryos. Twin pregnancies demonstrated no difference between the groups.

Diagnostic efficacy of aneuploidy markers correlated with early onset preeclampsia

Low-dose aspirin administration before 16 weeks of gestation can prevent preeclampsia (PE) more effectively. In order to determine if aspirin should be administered, this study aimed to investigate the predictive value of pregnancy-associated plasma protein A (PAPP-A) and aneuploidy markers for the onset period of PE. 1053 singleton pregnant women were included in the study, and serum PAPPA-A and aneuploidy markers were analyzed between 3 group (normotensive, late-onset PE, and early-onset PE). The utility of these markers for predicting early-onset preeclampsia (EOPE) was compared using each marker and their combination. Alpha-fetoprotein (AFP)/PAPP-A > 6.89 and human chorionic gonadotropin (hCG)/PAPP-A > 7.94 were associated with EOPE with a positive likelihood ratio (LR) (6.52, 95% confidence interval [CI] 4.9-7.1), and (5.77, 95% CI 3.9-6.4). The combination of markers could predict EOPE more accurately compared to the single markers. AFP/PAPP-A > 6.89 and hCG/PAPP-A > 7.94had a predictive ability for EOPE, and these cutoff values can help determine the use of aspirin at an earlier gestational age (GA).

No. 261-Prenatal Screening for Fetal Aneuploidy in Singleton Pregnancies

OBJECTIVE

To develop a Canadian consensus document on maternal screening for fetal aneuploidy (e.g., Down syndrome and trisomy 18) in singleton pregnancies.

OPTIONS

Pregnancy screening for fetal aneuploidy started in the mid 1960s, using maternal age as the screening test. New developments in maternal serum and ultrasound screening have made it possible to offer all pregnant patients a non-invasive screening test to assess their risk of having a fetus with aneuploidy to determine whether invasive prenatal diagnostic testing is necessary. This document reviews the options available for non-invasive screening and makes recommendations for Canadian patients and health care workers.

OUTCOMES

To offer non-invasive screening for fetal aneuploidy (trisomy 13, 18, 21) to all pregnant women. Invasive prenatal diagnosis would be offered to women who screen above a set risk cut-off level on non-invasive screening or to pregnant women whose personal, obstetrical, or family history places them at increased risk. Currently available non-invasive screening options include maternal age combined with one of the following: (1) first trimester screening (nuchal translucency, maternal age, and maternal serum biochemical markers), (2) second trimester serum screening (maternal age and maternal serum biochemical markers), or (3) 2-step integrated screening, which includes first and second trimester serum screening with or without nuchal translucency (integrated prenatal screen, serum integrated prenatal screening, contingent, and sequential). These options are reviewed, and recommendations are made.

EVIDENCE

Studies published between 1982 and 2009 were retrieved through searches of PubMed or Medline and CINAHL and the Cochrane Library, using appropriate controlled vocabulary and key words (aneuploidy, Down syndrome, trisomy, prenatal screening, genetic health risk, genetic health surveillance, prenatal diagnosis). Results were restricted to systematic reviews, randomized controlled trials, and relevant observational studies. There were no language restrictions. Searches were updated on a regular basis and incorporated in the guideline to August 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment- related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. The previous Society of Obstetricians and Gynaecologists of Canada guidelines regarding prenatal screening were also reviewed in developing this clinical practice guideline.

VALUES

The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care.

BENEFITS, HARMS, AND COSTS

This guideline is intended to reduce the number of prenatal invasive procedures done when maternal age is the only indication. This will have the benefit of reducing the numbers of normal pregnancies lost because of complications of invasive procedures. Any screening test has an inherent false- positive rate, which may result in undue anxiety. It is not possible at this time to undertake a detailed cost-benefit analysis of the implementation of this guideline, since this would require health surveillance and research and health resources not presently available; however, these factors need to be evaluated in a prospective approach by provincial and territorial initiatives.

RECOMMENDATIONS

First trimester ultrasound tests alone or in combination with first trimester serum tests for Down's syndrome screening

BACKGROUND

Down's syndrome occurs when a person has three, rather than two copies of chromosome 21; or the specific area of chromosome 21 implicated in causing Down's syndrome. It is the commonest congenital cause of mental disability and also leads to numerous metabolic and structural problems. It can be life-threatening, or lead to considerable ill health, although some individuals have only mild problems and can lead relatively normal lives. Having a baby with Down's syndrome is likely to have a significant impact on family life.Non-invasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing.Before agreeing to screening tests, parents need to be fully informed about the risks, benefits and possible consequences of such a test. This includes subsequent choices for further tests they may face, and the implications of both false positive and false negative screening tests (i.e. invasive diagnostic testing, and the possibility that a miscarried fetus may be chromosomally normal). The decisions that may be faced by expectant parents inevitably engender a high level of anxiety at all stages of the screening process, and the outcomes of screening can be associated with considerable physical and psychological morbidity. No screening test can predict the severity of problems a person with Down's syndrome will have.

OBJECTIVES

To estimate and compare the accuracy of first trimester ultrasound markers alone, and in combination with first trimester serum tests for the detection of Down's syndrome.

SEARCH METHODS

We carried out extensive literature searches including MEDLINE (1980 to 25 August 2011), Embase (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), and The Database of Abstracts of Reviews of Effects (the Cochrane Library 2011, Issue 7). We checked reference lists and published review articles for additional potentially relevant studies.

SELECTION CRITERIA

Studies evaluating tests of first trimester ultrasound screening, alone or in combination with first trimester serum tests (up to 14 weeks' gestation) for Down's syndrome, compared with a reference standard, either chromosomal verification or macroscopic postnatal inspection.

DATA COLLECTION AND ANALYSIS

Data were extracted as test positive/test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS criteria. We used hierarchical summary ROC meta-analytical methods to analyse test performance and compare test accuracy. Analysis of studies allowing direct comparison between tests was undertaken. We investigated the impact of maternal age on test performance in subgroup analyses.

MAIN RESULTS

We included 126 studies (152 publications) involving 1,604,040 fetuses (including 8454 Down's syndrome cases). Studies were generally good quality, although differential verification was common with invasive testing of only high-risk pregnancies. Sixty test combinations were evaluated formed from combinations of 11 different ultrasound markers (nuchal translucency (NT), nasal bone, ductus venosus Doppler, maxillary bone length, fetal heart rate, aberrant right subclavian artery, frontomaxillary facial angle, presence of mitral gap, tricuspid regurgitation, tricuspid blood flow and iliac angle 90 degrees); 12 serum tests (inhibin A, alpha-fetoprotein (AFP), free beta human chorionic gonadotrophin (ßhCG), total hCG, pregnancy-associated plasma protein A (PAPP-A), unconjugated oestriol (uE3), disintegrin and metalloprotease 12 (ADAM 12), placental growth factor (PlGF), placental growth hormone (PGH), invasive trophoblast antigen (ITA) (synonymous with hyperglycosylated hCG), growth hormone binding protein (GHBP) and placental protein 13 (PP13)); and maternal age. The most frequently evaluated serum markers in combination with ultrasound markers were PAPP-A and free ßhCG.Comparisons of the 10 most frequently evaluated test strategies showed that a combined NT, PAPP-A, free ßhCG and maternal age test strategy significantly outperformed ultrasound markers alone (with or without maternal age) except nasal bone, detecting about nine out of every 10 Down's syndrome pregnancies at a 5% false positive rate (FPR). In both direct and indirect comparisons, the combined NT, PAPP-A, free ßhCG and maternal age test strategy showed superior diagnostic accuracy to an NT and maternal age test strategy (P < 0.0001). Based on the indirect comparison of all available studies for the two tests, the sensitivity (95% confidence interval) estimated at a 5% FPR for the combined NT, PAPP-A, free ßhCG and maternal age test strategy (69 studies; 1,173,853 fetuses including 6010 with Down's syndrome) was 87% (86 to 89) and for the NT and maternal age test strategy (50 studies; 530,874 fetuses including 2701 Down's syndrome pregnancies) was 71% (66 to 75). Combinations of NT with other ultrasound markers, PAPP-A and free ßhCG were evaluated in one or two studies and showed sensitivities of more than 90% and specificities of more than 95%.High-risk populations (defined before screening was done, mainly due to advanced maternal age of 35 years or more, or previous pregnancies affected with Down's syndrome) showed lower detection rates compared to routine screening populations at a 5% FPR. Women who miscarried in the over 35 group were more likely to have been offered an invasive test to verify a negative screening results, whereas those under 35 were usually not offered invasive testing for a negative screening result. Pregnancy loss in women under 35 therefore leads to under-ascertainment of screening results, potentially missing a proportion of affected pregnancies and affecting test sensitivity. Conversely, for the NT, PAPP-A, free ßhCG and maternal age test strategy, detection rates and false positive rates increased with maternal age in the five studies that provided data separately for the subset of women aged 35 years or more.

AUTHORS' CONCLUSIONS

Test strategies that combine ultrasound markers with serum markers, especially PAPP-A and free ßhCG, and maternal age were significantly better than those involving only ultrasound markers (with or without maternal age) except nasal bone. They detect about nine out of 10 Down's affected pregnancies for a fixed 5% FPR. Although the absence of nasal bone appeared to have a high diagnostic accuracy, only five out of 10 affected Down's pregnancies were detected at a 1% FPR.

First and second trimester serum tests with and without first trimester ultrasound tests for Down's syndrome screening

BACKGROUND

Down's syndrome occurs when a person has three copies of chromosome 21 (or the specific area of chromosome 21 implicated in causing Down's syndrome) rather than two. It is the commonest congenital cause of mental disability. Non-invasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing.  Before agreeing to screening tests, parents need to be fully informed about the risks, benefits and possible consequences of such a test. This includes subsequent choices for further tests they may face, and the implications of both false positive (i.e. invasive diagnostic testing, and the possibility that a miscarried fetus may be chromosomally normal) and false negative screening tests (i.e. a fetus with Down's syndrome will be missed). The decisions that may be faced by expectant parents inevitably engender a high level of anxiety at all stages of the screening process, and the outcomes of screening can be associated with considerable physical and psychological morbidity. No screening test can predict the severity of problems a person with Down's syndrome will have.

OBJECTIVES

To estimate and compare the accuracy of first and second trimester serum markers with and without first trimester ultrasound markers for the detection of Down's syndrome in the antenatal period, as combinations of markers.

SEARCH METHODS

We conducted a sensitive and comprehensive literature search of MEDLINE (1980 to 25 August 2011), Embase (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), the Database of Abstracts of Reviews of Effectiveness (the Cochrane Library 25 August 2011), MEDION (25 August 2011), the Database of Systematic Reviews and Meta-Analyses in Laboratory Medicine (25 August 2011), the National Research Register (Archived 2007), and Health Services Research Projects in Progress database (25 August 2011). We did not apply a diagnostic test search filter. We did forward citation searching in ISI citation indices, Google Scholar and PubMed 'related articles'. We also searched reference lists of retrieved articles SELECTION CRITERIA: Studies evaluating tests of combining first and second trimester maternal serum markers in women up to 24 weeks of gestation for Down's syndrome, with or without first trimester ultrasound markers, compared with a reference standard, either chromosomal verification or macroscopic postnatal inspection.

DATA COLLECTION AND ANALYSIS

Data were extracted as test positive/test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS criteria. We used hierarchical summary ROC meta-analytical methods to analyse test performance and compare test accuracy. Analysis of studies allowing direct comparison between tests was undertaken. We investigated the impact of maternal age on test performance in subgroup analyses.

MAIN RESULTS

Twenty-two studies (reported in 25 publications) involving 228,615 pregnancies (including 1067 with Down's syndrome) were included. Studies were generally high quality, although differential verification was common with invasive testing of only high risk pregnancies. Ten studies made direct comparisons between tests. Thirty-two different test combinations were evaluated formed from combinations of eight different tests and maternal age; first trimester nuchal translucency (NT) and the serum markers AFP, uE3, total hCG, free βhCG, Inhibin A, PAPP-A and ADAM 12. We looked at tests combining first and second trimester markers with or without ultrasound as complete tests, and we also examined stepwise and contingent strategies.Meta-analysis of the six most frequently evaluated test combinations showed that a test strategy involving maternal age and a combination of first trimester NT and PAPP-A, and second trimester total hCG, uE3, AFP and Inhibin A significantly outperformed other test combinations that involved only one serum marker or NT in the first trimester, detecting about nine out of every 10 Down's syndrome pregnancies at a 5% false positive rate. However, the evidence was limited in terms of the number of studies evaluating this strategy, and we therefore cannot recommend one single screening strategy.

AUTHORS' CONCLUSIONS

Tests involving first trimester ultrasound with first and second trimester serum markers in combination with maternal age are significantly better than those without ultrasound, or those evaluating first trimester ultrasound in combination with second trimester serum markers, without first trimester serum markers. We cannot make recommendations about a specific strategy on the basis of the small number of studies available.

Urine tests for Down's syndrome screening

BACKGROUND

Down's syndrome occurs when a person has three copies of chromosome 21, or the specific area of chromosome 21 implicated in causing Down's syndrome, rather than two. It is the commonest congenital cause of mental disability and also leads to numerous metabolic and structural problems. It can be life-threatening, or lead to considerable ill health, although some individuals have only mild problems and can lead relatively normal lives. Having a baby with Down's syndrome is likely to have a significant impact on family life. The risk of a Down's syndrome affected pregnancy increases with advancing maternal age.Noninvasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing. Before agreeing to screening tests, parents need to be fully informed about the risks, benefits and possible consequences of such a test. This includes subsequent choices for further tests they may face, and the implications of both false positive and false negative screening tests (i.e. invasive diagnostic testing, and the possibility that a miscarried fetus may be chromosomally normal). The decisions that may be faced by expectant parents inevitably engender a high level of anxiety at all stages of the screening process, and the outcomes of screening can be associated with considerable physical and psychological morbidity. No screening test can predict the severity of problems a person with Down's syndrome will have.

OBJECTIVES

To estimate and compare the accuracy of first and second trimester urine markers for the detection of Down's syndrome.

SEARCH METHODS

We carried out a sensitive and comprehensive literature search of MEDLINE (1980 to 25 August 2011), EMBASE (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), The Database of Abstracts of Reviews of Effectiveness (The Cochrane Library 2011, Issue 7), MEDION (25 August 2011), The Database of Systematic Reviews and Meta-Analyses in Laboratory Medicine (25 August 2011), The National Research Register (archived 2007), Health Services Research Projects in Progress database (25 August 2011). We studied reference lists and published review articles.

SELECTION CRITERIA

Studies evaluating tests of maternal urine in women up to 24 weeks of gestation for Down's syndrome, compared with a reference standard, either chromosomal verification or macroscopic postnatal inspection.

DATA COLLECTION AND ANALYSIS

We extracted data as test positive or test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria. We used hierarchical summary ROC (receiver operating characteristic) meta-analytical methods to analyse test performance and compare test accuracy. We performed analysis of studies allowing direct comparison between tests. We investigated the impact of maternal age on test performance in subgroup analyses.

MAIN RESULTS

We included 19 studies involving 18,013 pregnancies (including 527 with Down's syndrome). Studies were generally of high quality, although differential verification was common with invasive testing of only high-risk pregnancies. Twenty-four test combinations were evaluated formed from combinations of the following seven different markers with and without maternal age: AFP (alpha-fetoprotein), ITA (invasive trophoblast antigen), ß-core fragment, free ßhCG (beta human chorionic gonadotrophin), total hCG, oestriol, gonadotropin peptide and various marker ratios. The strategies evaluated included three double tests and seven single tests in combination with maternal age, and one triple test, two double tests and 11 single tests without maternal age. Twelve of the 19 studies only evaluated the performance of a single test strategy while the remaining seven evaluated at least two test strategies. Two marker combinations were evaluated in more than four studies; second trimester ß-core fragment (six studies), and second trimester ß-core fragment with maternal age (five studies).In direct test comparisons, for a 5% false positive rate (FPR), the diagnostic accuracy of the double marker second trimester ß-core fragment and oestriol with maternal age test combination was significantly better (ratio of diagnostic odds ratio (RDOR): 2.2 (95% confidence interval (CI) 1.1 to 4.5), P = 0.02) (summary sensitivity of 73% (CI 57 to 85) at a cut-point of 5% FPR) than that of the single marker test strategy of second trimester ß-core fragment and maternal age (summary sensitivity of 56% (CI 45 to 66) at a cut-point of 5% FPR), but was not significantly better (RDOR: 1.5 (0.8 to 2.8), P = 0.21) than that of the second trimester ß-core fragment to oestriol ratio and maternal age test strategy (summary sensitivity of 71% (CI 51 to 86) at a cut-point of 5% FPR).

AUTHORS' CONCLUSIONS

Tests involving second trimester ß-core fragment and oestriol with maternal age are significantly more sensitive than the single marker second trimester ß-core fragment and maternal age, however, there were few studies. There is a paucity of evidence available to support the use of urine testing for Down's syndrome screening in clinical practice where alternatives are available.

First trimester serum tests for Down's syndrome screening

BACKGROUND

Down's syndrome occurs when a person has three, rather than two copies of chromosome 21; or the specific area of chromosome 21 implicated in causing Down's syndrome. It is the commonest congenital cause of mental disability and also leads to numerous metabolic and structural problems. It can be life-threatening, or lead to considerable ill health, although some individuals have only mild problems and can lead relatively normal lives. Having a baby with Down's syndrome is likely to have a significant impact on family life.Noninvasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing. However, no test can predict the severity of problems a person with Down's syndrome will have.

OBJECTIVES

The aim of this review was to estimate and compare the accuracy of first trimester serum markers for the detection of Down's syndrome in the antenatal period, both as individual markers and as combinations of markers. Accuracy is described by the proportion of fetuses with Down's syndrome detected by screening before birth (sensitivity or detection rate) and the proportion of women with a low risk (normal) screening test result who subsequently had a baby unaffected by Down's syndrome (specificity).

SEARCH METHODS

We conducted a sensitive and comprehensive literature search of MEDLINE (1980 to 25 August 2011), Embase (1980 to 25 August 2011), BIOSIS via EDINA (1985 to 25 August 2011), CINAHL via OVID (1982 to 25 August 2011), The Database of Abstracts of Reviews of Effectiveness (The Cochrane Library 25 August 2011), MEDION (25 August 2011), The Database of Systematic Reviews and Meta-Analyses in Laboratory Medicine (25 August 2011), The National Research Register (Archived 2007), Health Services Research Projects in Progress database (25 August 2011). We did forward citation searching ISI citation indices, Google Scholar and PubMed 'related articles'. We did not apply a diagnostic test search filter. We also searched reference lists and published review articles.  

SELECTION CRITERIA

We included studies in which all women from a given population had one or more index test(s) compared to a reference standard (either chromosomal verification or macroscopic postnatal inspection). Both consecutive series and diagnostic case-control study designs were included. Randomised trials where individuals were randomised to different screening strategies and all verified using a reference standard were also eligible for inclusion. Studies in which test strategies were compared head-to-head either in the same women, or between randomised groups were identified for inclusion in separate comparisons of test strategies. We excluded studies if they included less than five Down's syndrome cases, or more than 20% of participants were not followed up.

DATA COLLECTION AND ANALYSIS

We extracted data as test positive or test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria. We used hierarchical summary ROC meta-analytical methods or random-effects logistic regression methods to analyse test performance and compare test accuracy as appropriate. Analyses of studies allowing direct and indirect comparisons between tests were undertaken.

MAIN RESULTS

We included 56 studies (reported in 68 publications) involving 204,759 pregnancies (including 2113 with Down's syndrome). Studies were generally of good quality, although differential verification was common with invasive testing of only high-risk pregnancies. We evaluated 78 test combinations formed from combinations of 18 different tests, with or without maternal age; ADAM12 (a disintegrin and metalloprotease), AFP (alpha-fetoprotein), inhibin, PAPP-A (pregnancy-associated plasma protein A, ITA (invasive trophoblast antigen), free βhCG (beta human chorionic gonadotrophin), PlGF (placental growth factor), SP1 (Schwangerschafts protein 1), total hCG, progesterone, uE3 (unconjugated oestriol), GHBP (growth hormone binding protein), PGH (placental growth hormone), hyperglycosylated hCG, ProMBP (proform of eosinophil major basic protein), hPL (human placental lactogen), (free αhCG, and free ßhCG to AFP ratio. Direct comparisons between two or more tests were made in 27 studies.Meta-analysis of the nine best performing or frequently evaluated test combinations showed that a test strategy involving maternal age and a double marker combination of PAPP-A and free ßhCG significantly outperformed the individual markers (with or without maternal age) detecting about seven out of every 10 Down's syndrome pregnancies at a 5% false positive rate (FPR). Limited evidence suggested that marker combinations involving PAPP-A may be more sensitive than those without PAPP-A.

AUTHORS' CONCLUSIONS

Tests involving two markers in combination with maternal age, specifically PAPP-A, free βhCG and maternal age are significantly better than those involving single markers with and without age. They detect seven out of 10 Down's affected pregnancies for a fixed 5% FPR. The addition of further markers (triple tests) has not been shown to be statistically superior; the studies included are small with limited power to detect a difference.The screening blood tests themselves have no adverse effects for the woman, over and above the risks of a routine blood test. However some women who have a 'high risk' screening test result, and are given amniocentesis or chorionic villus sampling (CVS) have a risk of miscarrying a baby unaffected by Down's. Parents will need to weigh up this risk when deciding whether or not to have an amniocentesis or CVS following a 'high risk' screening test result.

Second trimester serum tests for Down's Syndrome screening

BACKGROUND

Down's syndrome occurs when a person has three copies of chromosome 21 - or the specific area of chromosome 21 implicated in causing Down's syndrome - rather than two. It is the commonest congenital cause of mental retardation. Noninvasive screening based on biochemical analysis of maternal serum or urine, or fetal ultrasound measurements, allows estimates of the risk of a pregnancy being affected and provides information to guide decisions about definitive testing.  

OBJECTIVES

To estimate and compare the accuracy of second trimester serum markers for the detection of Down's syndrome.

SEARCH METHODS

We carried out a sensitive and comprehensive literature search of MEDLINE (1980 to May 2007), EMBASE (1980 to 18 May 2007), BIOSIS via EDINA (1985 to 18 May 2007), CINAHL via OVID (1982 to 18 May 2007), The Database of Abstracts of Reviews of Effectiveness (The Cochrane Library 2007, Issue 1), MEDION (May 2007), The Database of Systematic Reviews and Meta-Analyses in Laboratory Medicine (May 2007), The National Research Register (May 2007), Health Services Research Projects in Progress database (May 2007). We studied reference lists and published review articles.  

SELECTION CRITERIA

Studies evaluating tests of maternal serum in women at 14-24 weeks of gestation for Down's syndrome, compared with a reference standard, either chromosomal verification or macroscopic postnatal inspection.

DATA COLLECTION AND ANALYSIS

Data were extracted as test positive/test negative results for Down's and non-Down's pregnancies allowing estimation of detection rates (sensitivity) and false positive rates (1-specificity). We performed quality assessment according to QUADAS criteria. We used hierarchical summary ROC meta-analytical methods to analyse test performance and compare test accuracy. Analysis of studies allowing direct comparison between tests was undertaken. We investigated the impact of maternal age on test performance in subgroup analyses.

MAIN RESULTS

Fifty-nine studies involving 341,261 pregnancies (including 1,994 with Down's syndrome) were included. Studies were generally high quality, although differential verification was common with invasive testing of only high-risk pregnancies. Seventeen studies made direct comparisons between tests. Fifty-four test combinations were evaluated formed from combinations of 12 different tests and maternal age; alpha-fetoprotein (AFP), unconjugated oestriol (uE3), total human chorionic gonadotrophin (hCG), free beta human chorionic gonadotrophin (βhCG), free alpha human chorionic gonadotrophin (αhCG), Inhibin A, SP2, CA125, troponin, pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PGF) and proform of eosinophil major basic protein (ProMBP).Meta-analysis of 12 best performing or frequently evaluated test combinations showed double and triple tests (involving AFP, uE3, total hCG, free βhCG) significantly outperform individual markers, detecting six to seven out of every 10 Down's syndrome pregnancies at a 5% false positive rate. Tests additionally involving inhibin performed best (eight out of every 10 Down's syndrome pregnancies) but were not shown to be significantly better than standard triple tests in direct comparisons. Significantly lower sensitivity occurred in women over the age of 35 years. Women who miscarried in the over 35 group were more likely to have been offered an invasive test to verify a negative screening results, whereas those under 35 were usually not offered invasive testing for a negative screening result. Pregnancy loss in women under 35 therefore leads to under ascertainment of screening results, potentially missing a proportion of affected pregnancies and affecting the accuracy of the sensitivity.

AUTHORS' CONCLUSIONS

Tests involving two or more markers in combination with maternal age are significantly more sensitive than those involving one marker. The value of combining four or more tests or including inhibin have not been proven to show statistically significant improvement. Further study is required to investigate reduced test performance in women aged over 35 and the impact of differential pregnancy loss on study findings.

Prenatal screening for fetal aneuploidy in singleton pregnancies

OBJECTIVE

To develop a Canadian consensus document on maternal screening for fetal aneuploidy (e.g., Down syndrome and trisomy 18) in singleton pregnancies.

OPTIONS

Pregnancy screening for fetal aneuploidy started in the mid 1960s, using maternal age as the screening test. New developments in maternal serum and ultrasound screening have made it possible to offer all pregnant patients a non-invasive screening test to assess their risk of having a fetus with aneuploidy to determine whether invasive prenatal diagnostic testing is necessary. This document reviews the options available for non-invasive screening and makes recommendations for Canadian patients and health care workers.

OUTCOMES

To offer non-invasive screening for fetal aneuploidy (trisomy 13, 18, 21) to all pregnant women. Invasive prenatal diagnosis would be offered to women who screen above a set risk cut-off level on non-invasive screening or to pregnant women whose personal, obstetrical, or family history places them at increased risk. Currently available non-invasive screening options include maternal age combined with one of the following: (1) first trimester screening (nuchal translucency, maternal age, and maternal serum biochemical markers), (2) second trimester serum screening (maternal age and maternal serum biochemical markers), or (3) 2-step integrated screening, which includes first and second trimester serum screening with or without nuchal translucency (integrated prenatal screen, serum integrated prenatal screening, contingent, and sequential). These options are reviewed, and recommendations are made.

EVIDENCE

Studies published between 1982 and 2009 were retrieved through searches of PubMed or Medline and CINAHL and the Cochrane Library, using appropriate controlled vocabulary and key words (aneuploidy, Down syndrome, trisomy, prenatal screening, genetic health risk, genetic health surveillance, prenatal diagnosis). Results were restricted to systematic reviews, randomized controlled trials, and relevant observational studies. There were no language restrictions. Searches were updated on a regular basis and incorporated in the guideline to August 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. The previous Society of Obstetricians and Gynaecologists of Canada guidelines regarding prenatal screening were also reviewed in developing this clinical practice guideline.

VALUES

The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care.

BENEFITS, HARMS, AND COSTS

This guideline is intended to reduce the number of prenatal invasive procedures done when maternal age is the only indication. This will have the benefit of reducing the numbers of normal pregnancies lost because of complications of invasive procedures. Any screening test has an inherent false-positive rate, which may result in undue anxiety. It is not possible at this time to undertake a detailed cost-benefit analysis of the implementation of this guideline, since this would require health surveillance and research and health resources not presently available; however, these factors need to be evaluated in a prospective approach by provincial and territorial initiatives. RECOMMENDATIONS 1. All pregnant women in Canada, regardless of age, should be offered, through an informed counselling process, the option of a prenatal screening test for the most common clinically significant fetal aneuploidies in addition to a second trimester ultrasound for dating, assessment of fetal anatomy, and detection of multiples. (I-A) 2. Counselling must be non-directive and must respect a woman's right to accept or decline any or all of the testing or options offered at any point in the process. (III-A) 3. Maternal age alone is a poor minimum standard for prenatal screening for aneuploidy, and it should not be used a basis for recommending invasive testing when non-invasive prenatal screening for aneuploidy is available. (II-2A) 4. Invasive prenatal diagnosis for cytogenetic analysis should not be performed without multiple marker screening results except for women who are at increased risk of fetal aneuploidy (a) because of ultrasound findings, (b) because the pregnancy was conceived by in vitro fertilization with intracytoplasmic sperm injection, or (c) because the woman or her partner has a history of a previous child or fetus with a chromosomal abnormality or is a carrier of a chromosome rearrangement that increases the risk of having a fetus with a chromosomal abnormality. (II-2E) 5. At minimum, any prenatal screen offered to Canadian women who present for care in the first trimester should have a detection rate of 75% with no more than a 3% false-positive rate. The performance of the screen should be substantiated by annual audit. (III-B) 6. The minimum standard for women presenting in the second trimester should be a screen that has a detection rate of 75% with no more than a 5% false-positive rate. The performance of the screen should be substantiated by annual audit. (III-B) 7. First trimester nuchal translucency should be interpreted for risk assessment only when measured by sonographers or sonologists trained and accredited for this service and when there is ongoing quality assurance (II-2A), and it should not be offered as a screen without biochemical markers in singleton pregnancies. (I-E) 8. Evaluation of the fetal nasal bone in the first trimester should not be incorporated as a screen unless it is performed by sonographers or sonologists trained and accredited for this service and there is ongoing quality assurance. (II-2E) 9. For women who undertake first trimester screening, second trimester serum alpha fetoprotein screening and/or ultrasound examination is recommended to screen for open neural tube defects. (II-1A) 10. Timely referral and access is critical for women and should be facilitated to ensure women are able to undergo the type of screening test they have chosen as first trimester screening. The first steps of integrated screening (with or without nuchal translucency), contingent, or sequential screening are performed in an early and relatively narrow time window. (II-1A) 11. Ultrasound dating should be performed if menstrual or conception dating is unreliable. For any abnormal serum screen calculated on the basis of menstrual dating, an ultrasound should be done to confirm gestational age. (II-1A) 12. The presence or absence of soft markers or anomalies in the 18- to 20-week ultrasound can be used to modify the a priori risk of aneuploidy established by age or prior screening. (II-2B) 13. Information such as gestational dating, maternal weight, ethnicity, insulin-dependent diabetes mellitus, and use of assisted reproduction technologies should be provided to the laboratory to improve accuracy of testing. (II-2A) 14. Health care providers should be aware of the screening modalities available in their province or territory. (III-B) 15. A reliable system needs to be in place ensuring timely reporting of results. (III-C) 16. Screening programs should be implemented with resources that support audited screening and diagnostic laboratory services, ultrasound, genetic counselling services, patient and health care provider education, and high quality diagnostic testing, as well as resources for administration, annual clinical audit, and data management. In addition, there must be the flexibility and funding to adjust the program to new technology and protocols. (II-3B).

The importance of growth factors for preimplantation embryo development and in-vitro culture

PURPOSE OF REVIEW

The present paper reviews evidence that preimplantation embryos are naturally exposed and designed to respond to growth factors during preimplantation development.

RECENT FINDINGS

Recent studies have demonstrated that in-vivo human preimplantation embryos are exposed to a mixture of many different growth factors, expressed by the follicles, oviducts and endometrium. Receptors for many of these growth factors have also been shown to be expressed by preimplantation embryos, suggesting a functional role during preimplantation development. Studies of in-vitro fertilization in both animals and humans indicate that in-vitro culture of embryos in conventional media lacking growth factors can result in suboptimal growth and a variety of short-term and long-term developmental abnormalities. Studies of embryo coculture indirectly suggest that growth factors can improve in-vitro development. Many studies of defined growth factor supplements demonstrate that their inclusion in culture media can substantially improve preimplantation development and efficacy of in-vitro fertilization, and may reduce long-term developmental abnormalities as well.

SUMMARY

Embryos are naturally exposed to a complex mixture of growth factors that play an important role in preimplantation embryo development and that are likely to be of substantial benefit if added to in-vitro culture media.

Prenatal Screening for Fetal Aneuploidy

This document has been archived because it contains outdated information. It should not be consulted for clinical use, but for historical research only. Please visit the journal website for the most recent guidelines.

Hormonal effects in infants conceived by assisted reproductive technology

OBJECTIVE

The purpose of this report is to describe 7 infants conceived by assisted reproductive technology (ART) who presented with breast development and/or pubic hair. The clinical presentation in these infants raises awareness that an altered intrauterine hormonal milieu may impact the fetal and infant stages of children conceived by ART.

METHODS

Between May 2001 and April 2004, 7 children between the ages of 5 and 21 months conceived by ART were referred by their pediatricians to the Division of Pediatric Endocrinology at the New York University School of Medicine for evaluation of possible precocious puberty. Patients were evaluated for the possibility of centrally mediated precocious puberty and pseudoprecocious puberty, with a possible ovarian or adrenal origin.

RESULTS

Endocrine evaluation in all patients indicated sex-steroid and hormone levels in the prepubertal range; pelvic sonography confirmed prepubertal ovaries with unstimulated uteri. Clinical follow-up of our patients thus far has not revealed progression of breast development, pubarche, or elevation in sex steroids.

CONCLUSIONS

It is well established that the developing endocrine system in the fetus and maturation of endocrine-control systems are influenced by hormone concentrations in the fetus. Whether ART alters the intrauterine hormonal milieu for the growing fetus conceived by ART is as yet unknown and is an area of ongoing investigation. Patients conceived through ART, including our patients who presented with hormonal manifestations, will need to be monitored throughout childhood and into adolescence and adulthood to determine if any perturbation exists on the timing of puberty and later fertility.

First trimester biochemical screening for Down's syndrome in singleton pregnancies conceived by assisted reproduction

BACKGROUND

Serum biochemical markers [free betahCG (fbetahCG); pregnancy-associated plasma protein-A (PAPP-A)] used in first trimester Down's syndrome screening have not been fully investigated in pregnancies achieved by assisted reproduction techniques. We present data on pregnancies conceived by all types of assisted reproduction techniques, including pregnancies following ovum donation (OD) and a large sample by ICSI.

METHODS

First trimester Down's syndrome screening was performed in 1054 normal singleton pregnancies: natural conception (n = 498), ovulation induction (OS, n = 97), IVF (n = 47), ICSI (n = 222) and OD (n = 190).

RESULTS

No differences in maternal levels of fbetahCG and PAPP-A, measured by the Kryptor system, appeared between naturally conceived pregnancies (n = 498) and those obtained with assisted reproduction techniques (n = 556). Several differences were apparent when comparing fbetahCG levels between different technologies but PAPP-A levels only differed between OS and IVF pregnancies (P < 0.05). In a further small study, no differences were observed using frozen embryos (n = 37), preimplantation genetic diagnosis (n = 53) or sperm from testicular biopsy (n = 21).

CONCLUSIONS

Data accumulated so far suggest that first trimester biochemical markers either do not need any adjustments (e.g. in pregnancies obtained after OS and ICSI), or have very little impact (e.g. IVF pregnancies) or no impact (e.g. OD pregnancies) on the false positive rates.

Maternal serum pregnancy-associated plasma protein-A and free β-human chorionic gonadotrophin in pregnancies conceived with fresh and frozen-thawed embryos fromin vitro fertilization and intracytoplasmic sperm injection

OBJECTIVE

Maternal serum pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotrophin (beta-hCG) are useful markers in the screening of Down syndrome in the first trimester. We investigated the effect of intracytoplasmic sperm injection (ICSI), freezing and thawing of embryos on the levels of these two analytes in assisted reproduction pregnancies.

METHODS

We recruited 149 women who conceived after assisted reproduction with fresh embryos (92 from conventional IVF and 57 from ICSI), 85 women who conceived with frozen-thawed embryos (54 from conventional IVF and 31 from ICSI) and 401 women with spontaneous conceptions as controls. The concentrations of PAPP-A and free beta-hCG were measured between 10 and 14 weeks and were converted to multiples of medians (MoM) for comparisons.

RESULTS

Median PAPP-A MoMs were significantly reduced in ICSI pregnancies in the fresh and frozen-thawed embryo subgroups (0.70 and 0.66 MoM respectively) and in the IVF fresh embryo subgroups (0.83 MoM), as compared to controls (1.00 MoM). Free beta-hCG MoM was significantly reduced in the IVF fresh embryos subgroup (0.87 MoM), but not in the other three subgroups.

CONCLUSION

Further studies for exploring the underlying pathophysiology and adjustment in the marker levels for screening of Down syndrome are warranted in pregnancies conceived after assisted reproduction.

Different preferences for prenatal diagnosis in pregnancies following assisted reproduction versus spontaneous conception

The uptake of prenatal diagnosis in 436 singleton and 146 twin pregnancies following assisted reproduction was compared with a matched group of spontaneous conceptions. The first and second trimester ultrasound examination included target fetal anatomic evaluation and screening by specific markers described for fetal aneuploidy. Women with assisted conception attended significantly more often for first trimester prenatal diagnosis (57.9 versus 34.9%, P < 0.01), but had fewer examinations in the early second trimester at 15-18 weeks (37.8 versus 48.8%, P < 0.01) than those with spontaneous conception. Screen positive results of 6.5 and 6.9% for first trimester examination and 6.0 and 7.3% for second trimester examination were found in assisted conceptions and controls respectively. A significantly higher rate of invasive prenatal diagnosis was observed in the second trimester for spontaneous conceptions, 20.0 versus 11.8% (P < 0.01) compared with assisted conceptions. This was attributed to the higher rate of invasive procedures in advanced maternal age >/=35 years of 40.7 versus 28.6% (P = 0.01) in spontaneous and assisted conceptions respectively. With the purpose of avoiding invasive testing, women with assisted conception were more likely to use the results of the ultrasound examination to guide their final decision about invasive testing, rather than undergo genetic amniocentesis as a first option.

Medically assisted reproduction and second-trimester maternal serum marker screening for Down syndrome

OBJECTIVES

To evaluate the effect of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) on total hCG, free ss-hCG, AFP and unconjugated estriol (uE3) used as markers for second-trimester Down syndrome maternal serum screening.

METHODS

Second-trimester maternal sera from 1515 singleton pregnancies (970 by IVF, 545 by ICSI) were compared with control sera (21 014 cases). Free ss-hCG, total hCG, AFP and uE3 were compared between the control group and the medically assisted reproduction groups. The percentages of at-risk patients (>/=1/250) were also compared.

RESULTS

No differences in values of the maternal serum markers were observed between the medically assisted and control groups. When maternal age was taken into account, the screen-positive rate for Down syndrome screening did not differ between the two groups.

CONCLUSION

Patients undergoing assisted reproduction techniques can be counseled for maternal serum Down syndrome screening with the same efficacy as patients with naturally conceived pregnancies.

Mid-gestation Down syndrome screening test and pregnancy outcome among unstimulated assisted-conception pregnancies

OBJECTIVES

Alteration of mid-gestation serum markers in assisted-conception pregnancies is believed to be attributable to ovarian superovulation treatment modalities. We compared alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), and unconjugated estriol (uE(3)) in two groups of unstimulated assisted-conception pregnancies, that is, own-oocyte frozen embryos (own-FET) versus oocyte-donated (OD) embryos.

METHODS

Forty-three OD-conceived and 31 own-FET-conceived singleton parturient women (aged 29 +/- 4 years and 31 +/- 4 years respectively, P < 0.05) were followed from embryo transfer throughout pregnancy.

RESULTS

The daily pattern of first-trimester serum beta-hCG was similar in both groups. The OD group had only significantly increased AFP concentrations compared to the own-FET group (1.38 vs 0.99 median MoM respectively, P = 0.002). Although there were no chromosomal abnormalities and no fetal or neonatal deaths in either group, 12% OD women and 6.5% own-FET women were found screen-positive. Eight OD women and 11 FET women had an adverse obstetric outcome (P = NS).

CONCLUSION

OD embryos are a unique clinical model for evaluating the uterine compartment and its contribution to mid-gestation serum marker secretion.

Amniotic fluid human chorionic gonadotrophin and alpha-fetoprotein levels in pregnancies conceived after assisted reproduction

OBJECTIVES

To study the alteration in the second-trimester maternal serum levels of human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) in pregnancies conceived after assisted reproduction.

METHODS

We compared the amniotic fluid hCG and AFP concentrations of 45 pregnancies with fresh embryo transfer and 25 pregnancies with frozen-thawed embryo transfer with 269 spontaneous pregnancies. Wilcoxon rank-sum test was used for analysis.

RESULTS

The median amniotic fluid hCG MoM in pregnancies conceived after frozen-thawed embryo transfer was significantly increased to 1.41 compared to 1.00 (p = 0.01) in naturally occurring pregnancies and 0.96 (p = 0.049) in pregnancies after fresh embryo transfer. Further analysis showed that this was only observed in frozen embryos fertilized by conventional insemination with MoM of 1.59. The AFP MoMs were similar among the groups.

CONCLUSIONS

The observed raised amniotic fluid hCG level in IVF-FET pregnancies may reflect the elevated maternal serum level in these pregnancies. Further studies should be directed towards exploring the underlying pathophysiology.