Low Maternal Serum Alpha-fetoprotein Research Articles

Relationship between first trimester vaginal bleeding and the risk of placental abruption

The aim of this study was to analyze influence of first trimester vaginal bleeding on the risk of placental abruption, as well as to assess the relation of first trimester bleeding and perinatal outcome in this patients with placental abruption. The second objective was to assess the connection of first trimester bleeding with low pregnancy-associated plasma protein-A and maternal serum alpha-fetoprotein with placental abruption. This is the first study that evaluated all relations these analytes in placental abruption with first trimester bleeding. Spontaneous, singleton pregnancies with live fetus ≥26 weeks of gestation with placental abruption were divided into two groups based on their prensence of first-trimester bleeding (Group 1) or without (Group 2). Maternal age, parity, smoking habits, body mass index, history of abortion and abruption, levels of pregnancy-associated plasma protein-A and Alpha-fetoprotein were also analyzed and compared. Main outcome measures were, mean gestational age, gender of baby, APGAR scores, birth length and weight and cesarean section rates. A total of 122 patients were included in the study.There were 44 patients accompanied with first trimester bleeding (group 1) and 78 patients without first trimester bleeding (group 2). The neonatal birthweight was significantly lower in first trimester bleeding group. The rate of smoking mother was significantly higher in first trimester bleeding group. Regarding serum maternal biomarkers, pregnancy-associated plasma protein-A≤0.5 and Alpha-fetoprotein ≥2 MOM was significantly higher in first trimester bleeding group.First trimester bleeding should alert clinicians for the signs of later possible complications in addition to low regnancy-associated plasma protein-A(≤0.5 MOM) and higher Alpha-fetoprotein (≥2 MOM) levels. Presence of vaginal bleeding in first trimester are related with poor maternal and fetal outcome at birth in patient with placental abruption.

Associations between pregnancy outcomes and unexplained high and low maternal serum alpha-fetoprotein levels.

To determine the relationship between adverse pregnancy outcomes and maternal serum alpha-fetoprotein (MSAFP) levels. A retrospective cohort study was conducted on consecutive singleton pregnancies, screened for fetal Down syndrome, in the northern part of Thailand. The prospective database of our fetal Down screening program was assessed to recruit all consecutive records. Pregnancies with medical complication and fetal abnormality were excluded. The recruited women were categorized into three groups: normal (≥0.76 to ≤2.0 MoM), low (<0.76 MoM) and high (>2.0 MoM) MSAFP levels. Of 7,110 screened women, 5,486 met inclusion criteria, including 240; 5,016 and 230 in the group of high, normal and low MSAFP levels, respectively. The rates of preterm birth, pregnancy-induced hypertension (PIH), fetal growth restriction (FGR), fetal death, low birth weight (LBW) and low APGAR scores were significantly higher in women with high MSAFP levels (11.7 vs. 6.6 %, 7.5 vs. 3.3 %, 7.5 vs. 3.3 %, 2.1 vs. 0.3 %, 15.8 vs. 6.7 %, and 2.9 vs. 0.5 % respectively), with relative risk of 1.76, 2.28, 2.27, 7.46, 2.35 and 6.09, respectively. The rates of preterm birth, FGR and LBW were significantly lower in low MSAFP levels with relative risk of 0.39, 0.26 and 0.26, respectively, whereas the rates of PIH and fetal death and low Apgar scores were not significantly different. Pregnant women with high MSAFP levels had an increased risk of poor pregnancy outcomes, while those with low MSAFP levels had a significantly lower risk of such outcomes.

Basic principles of prenatal screening for aneuploidies.

Prenatal screening processes are important public health interventions to counter common genetic disorders. For India prenatal screening against neural tube defects, thalassemia and Down syndrome is relevant to the health needs. However, there are many misconceptions regarding the principles of screening. Many clinicians wrongly consider it as substitute for prenatal diagnosis. Basically, prenatal screening protocols can be applied on a wide scale to identify women at risk of bearing a child with the common genetic disorder in that population. Prenatal screening for Down syndrome and other chromosomal abnormalities is a rapidly evolving science. It initially started with offering prenatal diagnosis to elderly mothers. The identification of low maternal serum alpha-fetoprotein levels as a marker in Down syndrome led to quest and recognition of many serum markers and maternal serum markers of AFP uE3 and hCG were used in combination as triple test and with addition of Inhibin as the quadruple test. The identification of Nuchal translucency as a marker in 1st trimester led to much desired early risk prediction along with PaPPA and free beta hCG. It was also found that this test led to early risk determination and an early prenatal diagnosis with significantly better detection rate of 85 to 90%. This detection rate is head and shoulders better than the detection rate for the triple test rate of 65 to 70%. It has also been noted that combination of these markers can also lead to risk prediction of other chromosomal abnormalities. Presently risk prediction is possible with some remarkable softwares for Trisomy 18, Trisomy 13, Turner syndrome, triploidy, Cornela de Lange syndrome, Smith Lemlie Opitz syndrome and others. New markers like ADAM 12 with PaPPA will lead to early prediction of PIH and IUGR as well as prematurity. It is envisaged that in future maternal serum markers in combination with fetal biometry will give risk prediction for numerous chromosomal abnormalities many fetal disorders as well as pregnancy disturbances. Thus prenatal screening has an important place in antenatal care.

Maternal Biochemical Serum Screening for Down Syndrome in Pregnancy With Human Immunodeficiency Virus Infection

To estimate the influence of human immunodeficiency virus (HIV) infection and antiretroviral therapy on maternal serum markers levels and the false-positive rate with biochemical maternal serum screening for Down syndrome. We performed a 1:1 matched case-control study comparing 132 HIV-infected women with single pregnancy to controls selected among non-HIV-infected women matched on geographical origin and fetal sex. Of HIV-infected women, 47.7% were receiving antiretroviral therapy. Groups did not differ in multiples of the median (MoM) levels of total human chorionic gonadotrophin. The MoM alpha fetoprotein level did not differ between total HIV-infected women and control women but was significantly lower for untreated HIV-positive women compared with control women (0.91 compared with 1.03 MoM, P<.01) and compared with treated HIV-positive women (0.91 compared with 1.18 MoM, P<.01). The false-positive rate of biochemical screening did not differ between groups. Untreated HIV infection is associated with lower maternal serum alpha fetoprotein levels. Nevertheless, the false-positive rate of double-marker second-trimester Down syndrome serum screening did not appear to be affected in our sample of HIV-infected women, whether women were receiving antiretroviral therapy at the time of the test or not.

Perinatal findings and molecular cytogenetic analyses of de novo interstitial deletion of 9q (9q22.3→q31.3) associated with Gorlin syndrome

To present the perinatal findings and the molecular cytogenetic analyses of a de novo interstitial deletion of 9q (9q22.3-->q31.3) associated with Gorlin syndrome. Amniocentesis was performed at 18 weeks' gestation on a 27-year-old woman at a community hospital because of a high Down syndrome risk of 1/178, a low maternal serum alpha-fetoprotein (MSAFP) level of 0.66 multiples of the median (MoM), and a high maternal serum human chorionic gonadotrophin (MShCG) level of 3.13 MoM. The karyotype was initially determined to be 46,XY. However, fetal macrocephaly and overgrowth were found at 30 weeks' gestation. Postnatally, the infant manifested characteristic features of Gorlin syndrome. High-resolution chromosomal bandings of the peripheral blood lymphocytes, polymorphic DNA marker analysis to determine the parental origin of the deletion, array comparative genomic hybridization (CGH) to determine the extent of the chromosomal deletion, and fluorescence in situ hybridization (FISH) to determine the deletion of the PTCH gene were performed. The 850-band level of resolution showed an interstitial deletion of 9q (9q22.3-->q31.3). The parental karyotypes were normal. The karyotype of the proband was 46,XY,del(9)(q22.3q31.3)de novo. Polymorphic DNA marker analysis revealed that the deletion was of paternal origin. Array CGH revealed that the deleted region was about 12 Mb, encompassing the segment from 9q22.32 to 9q31.3. FISH analysis using the BAC probe RP11-34D4 and the probe RP11-43505 indicated the deletion of the PTCH gene. Fetuses with an interstitial deletion of 9q (9q22.3-->q31.3) may be associated with a low level of MSAFP and a high level of MShCG in the second trimester, and sonographic findings of overgrowth and macrocephaly in the third trimester.

Small for gestational age infants and low maternal serum alpha-fetoprotein and estrogen levels in normal and hypertensive pregnancies

Small for gestational age infants and low maternal serum alpha-fetoprotein and estrogen levels in normal and hypertensive pregnancies

Unexplained Low Maternal Serum Alpha-fetoprotein and Birth Weight Outcomes

Unexplained Low Maternal Serum Alpha-fetoprotein and Birth Weight Outcomes

Unexplained low maternal serum alpha-fetoprotein and birth weight outcomes

Unexplained low maternal serum alpha-fetoprotein and birth weight outcomes

Very low second-trimester maternal serum alpha-fetoprotein: Association with high birth weight

OBJECTIVE: To investigate the relationship between very low maternal serum alpha-fetoprotein levels (MSAFP), neonatal size, and possible associations with obstetric complications. METHODS: This is a retrospective case-control study in a population managed prospectively by a standardized protocol. Perinatal outcomes were compared between patients with unexplained very low MSAFP (less than or equal to 0.25 multiples of the median) and control pregnancies with normal MSAFP, matched by precise gestational age, parity, maternal age within 1 year, and gender of the newborn. RESULTS: Of the 84,909 women screened, 464 (0.55%) met the definition of very low MSAFP. On tertiary evaluation, 226 had dates reassigned by ultrasound. After exclusion of overt diabetics, patients who were not pregnant, invalidated MSAFP, and 17 patients lost to follow-up, 178 women (0.21% of the total) had true very low MSAFP. True very low MSAFP was associated with subsequent miscarriage in 67 women and with fetal aneuploidy and/or serious abnormalities in 12 patients, leaving a population of 97 women (1.14 per 1000 women screened) with unexplained very low MSAFP. Without obvious demographic or obstetric factors, these women had heavier babies, more babies above the 90th percentile, more delivery complications caused by large birth weight (41 versus 16, χ 2, P < .001) compared with gestational-age matched controls from the same screened population who had normal MSAFP. CONCLUSION: Very low MSAFP predicts an unusually high rate of large birth weight infants, with increased fetal, intrapartum, and neonatal consequences. Maternal medical conditions or obvious demographic factors do not explain these consequences. These findings suggest a role for close fetal surveillance in the third trimester and extended efforts to assess maternal and neonatal glucose status.

Adverse Obstetric Outcome in Low- and High-Risk Pregnancies

In Brief Objective To determine whether the relationship between adverse pregnancy outcome and elevated maternal serum alpha-fetoprotein (MSAFP) and/or maternal serum hCG levels in women whose fetuses have no chromosomal abnormalities or neural tube defects is restricted to pregnancies with a priori elevated risk for pathology or also present in low-risk pregnancies. Methods The outcomes of pregnancy in two groups of patients with elevated MSAFP and/or maternal serum hCG values were compared with the outcomes of a reference group with normal serum values. The first study group consisted of 83 women without pre-existing risk for poor outcome as defined by the guidelines of the Dutch Society of Obstetrics and Gynecology. The second study group consisted of 62 women with a priori elevated risk according to these guidelines. Results Fetal or neonatal death, pregnancy-induced hypertension, placental abruption, placenta previa, preterm delivery, delivery of infants with birth weights in the 2.3rd percentile, and complications during the third stage of labor occurred significantly more often in patients with elevated values and low a priori risk than in women with normal values and without pre-existing risk factors. There was no significant increase in adverse pregnancy outcome in women with elevated values and high a priori risk compared with women with normal values and elevated a priori risk. Conclusion In women at low risk, elevated MSAFP and/or maternal serum hCG values are predictive of adverse pregnancy outcome. In women with a priori elevated risk, abnormal serum values do not increase this risk. Unexplained elevated serum alpha-fetoprotein or hCG levels increase the risk of adverse pregnancy outcome in women with low a priori risk but not in women with high a priori risk.

Adverse obstetric outcome in low- and high-risk pregnancies: predictive value of maternal serum screening

Objective: To determine whether the relationship between adverse pregnancy outcome and elevated maternal serum alpha-fetoprotein (MSAFP) and/or maternal serum hCG levels in women whose fetuses have no chromosomal abnormalities or neural tube defects is restricted to pregnancies with a priori elevated risk for pathology or also present in low-risk pregnancies. Methods: The outcomes of pregnancy in two groups of patients with elevated MSAFP and/or maternal serum hCG values were compared with the outcomes of a reference group with normal serum values. The first study group consisted of 83 women without pre-existing risk for poor outcome as defined by the guidelines of the Dutch Society of Obstetrics and Gynecology. The second study group consisted of 62 women with a priori elevated risk according to these guidelines. Results: Fetal or neonatal death, pregnancy-induced hypertension, placental abruption, placenta previa, preterm delivery, delivery of infants with birth weights in the 2.3rd percentile, and complications during the third stage of labor occurred significantly more often in patients with elevated values and low a priori risk than in women with normal values and without pre-existing risk factors. There was no significant increase in adverse pregnancy outcome in women with elevated values and high a priori risk compared with women with normal values and elevated a priori risk. Conclusion: In women at low risk, elevated MSAFP and/or maternal serum hCG values are predictive of adverse pregnancy outcome. In women with a priori elevated risk, abnormal serum values do not increase this risk.

Abnormal maternal serum alpha fetoprotein and pregnancy outcome

The objective was to assess the occurrence of miscarriages, low birth weight, and karyotype abnormalities found with low and elevated maternal serum alpha-fetoprotein (MSAFP) among women who had genetic amniocentesis performed. A retrospective study of 2,159 women who had MSAFP analysis prior to amniocentesis was conducted. Pregnancy outcomes were obtained from record review and physicians follow-up. Limits of MSAFP used in analysis were <0.5 adjusted multiples of the median (MOM) (lower levels) and >2.0 MOM (upper levels). Autosomal trisomy was found in 1.6% with low, 0.9% normal, and 0.6% with elevated MSAFP values. Sex chromosome abnormalities were present only in patients with normal MSAFP, [45X (n = 6), 47XXY (n = 2), 69XXX (2)]. Of five open neural tube defects, four had elevated MSAFP and one had a normal value. Omphalocele was identified in four patients, two with normal and two with elevated MSAFP. Gastroschisis was found in one low and one elevated MSAFP. Amniotic fluid alpha-fetoprotein (AFAFP) values did not correlate with MSAFP values. Patients with low MSAFP levels had a greater prevalence of abnormal karyotype (19 of 249, prevalence = 0.076) than patients with an elevated MSAFP level (2 or 166, prevalence = 0.012 OR (odds ratio) = 0.20 (Pvalue = 0.024) when unadjusted for maternal age, and OR = 0.09 (Pvalue = 0.001) when adjusted for maternal age. Spontaneous abortion occurred more often in patients with elevated (4 of 166, or 4%) than normal or low (20 of 1948, or 1%) values of MSAFP (odds ratio 4.32, P = 0.020 when adjusted for maternal age). Birth weight below 2,500 g was present less frequently with low or normal MSAFP (136 of 1,760, or 7.7%) than in elevated MSAFP (21 of 144 or 14.6%) (odds ratio 2.04, P = 0.005, unadjusted; and odds ratio = 2.32, P = 0.003, adjusted for maternal age). Female fetuses were present more often with low MSAFP (136 of 249, or 55%) than elevated levels 43% (71 of 164, or 43%; P = 0.024). We conclude that patients undergoing genetic amniocentesis with MSAFP <.5 MOM are less likely to miscarry, deliver a low birth weight newborn, or have a male infant than patients with MSAFP levels >2.0 MOM. J. Matern.–Fetal Med. 7:304–307, 1998. © 1998 Wiley-Liss, Inc.

Abnormal maternal serum alpha fetoprotein and pregnancy outcome.

The objective was to assess the occurrence of miscarriages, low birth weight, and karyotype abnormalities found with low and elevated maternal serum alpha-fetoprotein (MSAFP) among women who had genetic amniocentesis performed. A retrospective study of 2,159 women who had MSAFP analysis prior to amniocentesis was conducted. Pregnancy outcomes were obtained from record review and physicians follow-up. Limits of MSAFP used in analysis were <0.5 adjusted multiples of the median (MOM) (lower levels) and >2.0 MOM (upper levels). Autosomal trisomy was found in 1.6% with low, 0.9% normal, and 0.6% with elevated MSAFP values. Sex chromosome abnormalities were present only in patients with normal MSAFP, [45X (n = 6), 47XXY (n = 2), 69XXX]. Of five open neural tube defects, four had elevated MSAFP and one had a normal value. Omphalocele was identified in four patients, two with normal and two with elevated MSAFP. Gastroschisis was found in one low and one elevated MSAFP. Amniotic fluid alpha-fetoprotein (AFAFP) values did not correlate with MSAFP values. Patients with low MSAFP levels had a greater prevalence of abnormal karyotype (19 of 249, prevalence = 0.076) than patients with an elevated MSAFP level (2 or 166, prevalence = 0.012 OR (odds ratio) = 0.20 (P value = 0.024) when unadjusted for maternal age, and OR = 0.09 (P value = 0.001) when adjusted for maternal age. Spontaneous abortion occurred more often in patients with elevated (4 of 166, or 4%) than normal or low (20 of 1948, or 1%) values of MSAFP (odds ratio 4.32, P = 0.020 when adjusted for maternal age). Birth weight below 2,500 g was present less frequently with low or normal MSAFP (136 of 1,760, or 7.7%) than in elevated MSAFP (21 of 144 or 14.6%) (odds ratio 2.04, P = 0.005, unadjusted; and odds ratio = 2.32, P = 0.003, adjusted for maternal age). Female fetuses were present more often with low MSAFP (136 of 249, or 55%) than elevated levels 43% (71 of 164, or 43%; P = 0.024). We conclude that patients undergoing genetic amniocentesis with MSAFP <.5 MOM are less likely to miscarry, deliver a low birth weight newborn, or have a male infant than patients with MSAFP levels >2.0 MOM.

Antenatal screening for Down's syndrome.

Background In 1968 the first antenatal diagnosis of Down's syndrome was made and screening on the basis of selecting women of advanced maternal age for amniocentesis was gradually introduced into medical practice. In 1983 it was shown that low maternal serum alpha fetoprotein (AFP) was associated with Down's syndrome. Later, raised maternal serum human chorionic gonadotrophin (hCG), and low unconjugated oestriol (uE3) were found to be markers of Down's syndrome. In 1988 the three biochemical markers were used together with maternal age as a method of screening, and this has been widely adopted. PRINCIPLES OF ANTENATAL SCREENING FOR DOWN'S SYNDROME: Methods of screening need to be fully evaluated before being introduced into routine clinical practice. This included choosing markers for which there is sufficient scientific evidence of efficacy, quantifying performance in terms of detection and false positive rates, and establishing methods of monitoring performance. Screening needs to be provided as an integrated service, coordinating and managing the separate aspects of the screening process. SERUM MARKERS AT 15-22 WEEKS OF PREGNANCY: A large number of serum markers have been found to be associated with Down's syndrome between 15 and 22 weeks of pregnancy. The principal markers are AFP, hCG or its individual subunits (free alpha- and free beta-hCG), uE3, and inhibin A. Screening performance varies according to the choice of markers used and whether ultrasound is used to estimate gestational age (table 1). When an ultrasound scan is used to estimate gestational age the detection rate for a 5% false positive rate is estimated to be 59% using the double test (AFP and hCG), 69% using the triple test (AFP, hCG, uE3), and 76% using the quadruple test (AFP, hCG, uE3, inhibin A), all in combination with maternal age. Other factors that can usefully be taken into account in screening are maternal weight, the presence of insulin dependent diabetes mellitus, multiple pregnancy, ethnic origin, previous Down's syndrome pregnancy, and whether the test is the first one in a pregnancy or a repeat. Factors such as parity and smoking are associated with one or more of the serum markers, but the effect is too small to justify adjusting for these factors in interpreting a screening test. Urinary markers and fetal cells in maternal blood Urinary beta-core hCG has been investigated in a number of studies and shown to be raised in pregnancies with Down's syndrome. This area is currently the subject of active research and the use of urine in future screening programmes may be a practical possibility. Other urinary markers, such as total oestriol and free beta-hCG may also be of value. Fetal cells can be identified in the maternal circulation and techniques such as fluorescent in situ hybridisation can be used to identify aneuploidies, including Down's syndrome and trisomy 18. This approach may, in the future, be of value in screening or diagnosis. Currently, the techniques available do not have the performance, simplicity, or economy needed to replace existing methods. Demonstration projects Demonstration projects are valuable in determining the feasibility of screening and in refining the practical application of screening. They are of less value in determining the performance of different screening methods. Several demonstration projects have been conducted using the triple and double tests. In general, the uptake of screening was about 80%. The screen positive rates were about 5-6%. About 80% of women with positive screening results had an invasive diagnostic test, and of those found to have a pregnancy with Down's syndrome, about 90% chose to have a termination of pregnancy. ULTRASOUND MARKERS AT 15-22 WEEKS OF PREGNANCY: There are a number of ultrasound markers of Down's syndrome at 15-22 weeks, including nuchal fold thickness, cardiac abnormalities, duodenal atresia, femur length, humerus length, pyelectasis, and hyperechogenic bowel. (ABSTRA

Antenatal screening for Down's syndrome.

In 1968 the first antenatal diagnosis of Down's syndrome was made and screening on the basis of selecting women of advanced maternal age for amniocentesis was gradually introduced into medical practice. In 1983 it was shown that low maternal serum alpha fetoprotein (AFP) was associated with Down's syndrome. Later, raised maternal serum human chorionic gonadotrophin (hCG), and low unconjugated oestriol (uE3) were found to be markers of Down's syndrome. In 1988 the three biochemical markers were used together with maternal age as a method of screening, and this has been widely adopted. PRINCIPLES OF ANTENATAL SCREENING FOR DOWN'S SYNDROME: Methods of screening need to be fully evaluated before being introduced into routine clinical practice. This included choosing markers for which there is sufficient scientific evidence of efficacy, quantifying performance in terms of detection and false positive rates, and establishing methods of monitoring performance. Screening needs to be provided as an integrated service, coordinating and managing the separate aspects of the screening process. SERUM MARKERS AT 15-22 WEEKS OF PREGNANCY: A large number of serum markers have been found to be associated with Down's syndrome between 15 and 22 weeks of pregnancy. The principal markers are AFP, hCG or its individual subunits (free alpha- and free beta-hCG), uE3, and inhibin A. Screening performance varies according to the choice of markers used and whether ultrasound is used to estimate gestational age (table 1). When an ultrasound scan is used to estimate gestational age the detection rate for a 5% false positive rate is estimated to be 59% using the double test (AFP and hCG), 69% using the triple test (AFP, hCG, uE3), and 76% using the quadruple test (AFP, hCG, uE3, inhibin A), all in combination with maternal age. Other factors that can usefully be taken into account in screening are maternal weight, the presence of insulin dependent diabetes mellitus, multiple pregnancy, ethnic origin, previous Down's syndrome pregnancy, and whether the test is the first one in a pregnancy or a repeat. Factors such as parity and smoking are associated with one or more of the serum markers, but the effect is too small to justify adjusting for these factors in interpreting a screening test. Urinary beta-core hCG has been investigated in a number of studies and shown to be raised in pregnancies with Down's syndrome. This area is currently the subject of active research and the use of urine in future screening programmes may be a practical possibility. Other urinary markers, such as total oestriol and free beta-hCG may also be of value. Fetal cells can be identified in the maternal circulation and techniques such as fluorescent in situ hybridisation can be used to identify aneuploidies, including Down's syndrome and trisomy 18. This approach may, in the future, be of value in screening or diagnosis. Currently, the techniques available do not have the performance, simplicity, or economy needed to replace existing methods. Demonstration projects are valuable in determining the feasibility of screening and in refining the practical application of screening. They are of less value in determining the performance of different screening methods. Several demonstration projects have been conducted using the triple and double tests. In general, the uptake of screening was about 80%. The screen positive rates were about 5-6%. About 80% of women with positive screening results had an invasive diagnostic test, and of those found to have a pregnancy with Down's syndrome, about 90% chose to have a termination of pregnancy. ULTRASOUND MARKERS AT 15-22 WEEKS OF PREGNANCY: There are a number of ultrasound markers of Down's syndrome at 15-22 weeks, including nuchal fold thickness, cardiac abnormalities, duodenal atresia, femur length, humerus length, pyelectasis, and hyperechogenic bowel. (ABSTRA

Low MSAFP levels and Williams syndrome.

Williams syndrome (WS) is associated with a deletion of the elastin gene in over 90% of cases. We report maternal serum alpha feto-protein (MSAFP) levels in 5 women whose fetuses were later diagnosed as having WS. MSAFP levels ranged from 0.5-0.8 multiples of the median (MOM). Although further confirmation is necessary, it appears that MSAFP levels are lower than the median in WS. This apparent association has implications for counselling women following maternal serum screening.

Altered newborn gender distribution in patients with low mid-trimester maternal serum human chorionic gonadotropin (MShCG).

to determine if the sex ratio (male/female) is altered in infants born to patients with low mid-trimester maternal serum human chorionic gonadotropin (MShCG). Between 2/1/90 and 1/3/91, 3,116 patients underwent prenatal screening using second-trimester maternal serum alpha-fetoprotein (MSAFP), MShCG, and maternal serum unconjugated estriol (MSuE3). Among these, there were 132 patients with low second-trimester MShCG (< 0.4 MoM), normal MSAFP and MSuE3. The gender distribution of these term, normal newborns was compared to that of 237 controls, matched for race, maternal age, and referral source and delivered at term to mothers with normal mid-trimester MSAFP, MSuE3, and MShCG. The gender distribution of these two groups of newborns was also compared to that of 78 term newborns from the same obstetrical population delivered to mothers with second-trimester MShCG > 2.5 MoM and normal MSAFP and MSuE3. All patients had a complete obstetrical history. Forty-nine percent of the controls were male vs. 62% of the group with slow second-trimester MShCG (P < .01). Within the group with low MShCG, 59% of infants were male when the MShCG was between 0.19 and 0.4 MoM (A) and 80% when the MShCG was < 0.2 MoM (B) (control vs. A vs. B P < .005). The sex ratio in the high-MShCG group was similar to control. The data suggest that gender distribution is different from normal in patients with low mid-trimester MShCG.

Perinatal outcomes in a prospective matched pair study of pregnancy and unexplained elevated or low AFP screening.

Unexplained elevated or low maternal serum alpha-fetoprotein (MSAFP) is reported to indicate adverse perinatal outcome. We designed a prospective matched pair study to gain additional information about the type and frequency of adverse neonatal or maternal outcomes. Subjects were selected from 16,445 women who received second trimester MSAFP screening during the 4.5 year study period. For each unexplained elevated or low subject, a control patient in the second trimester of pregnancy was chosen by matching eight individual traits. After follow-up, 356 pairs were identified, for the unexplained low MSAFP group and 139 pairs for the unexplained elevated MSAFP group. Outcome information was obtained by way of a physician questionnaire. For the unexplained low MSAFP group, complications occurred no more often than for the paired controls and these pregnancies may not be considered at high risk for adverse outcome. Our study supports a strong association between unexplained elevated MSAFP and adverse neonatal outcomes of low birth weight, fetal death, preterm delivery, and fetal growth retardation. The highest frequency of adverse neonatal outcome occurred when the multiple of median value was > or = 4.0. Our study does not support an association between elevated MSAFP and maternal complications of hypertensive disorder, oligohydramnios, or placental abruption.

Antenatal Screening for Down's Syndrome

Background In 1968 the first antenatal diagnosis of Down's syndrome was made and screening on the basis of selecting women of advanced maternal age for amniocentesis was gradually introduced into medical practice. In 1983 it was shown that low maternal serum alpha fetoprotein (AFP) was associated with Down's syndrome. Later, raised maternal serum human chorionic gonadotrophin (hCG), and low unconjugated oestriol (uE3) were found to be markers of Down's syndrome. In 1988 the three biochemical markers were used together with maternal age as a method of screening, and this has been widely adopted. PRINCIPLES OF ANTENATAL SCREENING FOR DOWN'S SYNDROME: Methods of screening need to be fully evaluated before being introduced into routine clinical practice. This included choosing markers for which there is sufficient scientific evidence of efficacy, quantifying performance in terms of detection and false positive rates, and establishing methods of monitoring performance. Screening needs to be provided as an integrated service, coordinating and managing the separate aspects of the screening process. SERUM MARKERS AT 15-22 WEEKS OF PREGNANCY: A large number of serum markers have been found to be associated with Down's syndrome between 15 and 22 weeks of pregnancy. The principal markers are AFP, hCG or its individual subunits (free alpha- and free beta-hCG), uE3, and inhibin A. Screening performance varies according to the choice of markers used and whether ultrasound is used to estimate gestational age (table 1). When an ultrasound scan is used to estimate gestational age the detection rate for a 5% false positive rate is estimated to be 59% using the double test (AFP and hCG), 69% using the triple test (AFP, hCG, uE3), and 76% using the quadruple test (AFP, hCG, uE3, inhibin A), all in combination with maternal age. Other factors that can usefully be taken into account in screening are maternal weight, the presence of insulin dependent diabetes mellitus, multiple pregnancy, ethnic origin, previous Down's syndrome pregnancy, and whether the test is the first one in a pregnancy or a repeat. Factors such as parity and smoking are associated with one or more of the serum markers, but the effect is too small to justify adjusting for these factors in interpreting a screening test. Urinary markers and fetal cells in maternal blood Urinary beta-core hCG has been investigated in a number of studies and shown to be raised in pregnancies with Down's syndrome. This area is currently the subject of active research and the use of urine in future screening programmes may be a practical possibility. Other urinary markers, such as total oestriol and free beta-hCG may also be of value. Fetal cells can be identified in the maternal circulation and techniques such as fluorescent in situ hybridisation can be used to identify aneuploidies, including Down's syndrome and trisomy 18. This approach may, in the future, be of value in screening or diagnosis. Currently, the techniques available do not have the performance, simplicity, or economy needed to replace existing methods. Demonstration projects Demonstration projects are valuable in determining the feasibility of screening and in refining the practical application of screening. They are of less value in determining the performance of different screening methods. Several demonstration projects have been conducted using the triple and double tests. In general, the uptake of screening was about 80%. The screen positive rates were about 5-6%. About 80% of women with positive screening results had an invasive diagnostic test, and of those found to have a pregnancy with Down's syndrome, about 90% chose to have a termination of pregnancy. ULTRASOUND MARKERS AT 15-22 WEEKS OF PREGNANCY: There are a number of ultrasound markers of Down's syndrome at 15-22 weeks, including nuchal fold thickness, cardiac abnormalities, duodenal atresia, femur length, humerus length, pyelectasis, and hyperechogenic bowel. (ABSTRA

Clinical significance of low levels of second-trimester maternal serum human chorionic gonadotropin.

To determine if unexplained low second-trimester maternal serum human chorionic gonadotropin (MShCG) is a useful predictor of complications of pregnancy. Between 2/1/90 and 1/3/91, 3,116 patients underwent prenatal screening using second-trimester maternal serum alpha-fetoprotein (MSAFP), MShCG and maternal serum unconjugated estriol (MSuE3). Among these, there were 160 patients with complete obstetrical history who had second-trimester MShCG < 0.4 multiples of the median (MoM). These were compared to 261 controls with complete obstetrical history and a normal second-trimester MSAFP, MSuE3 and MShCG. No differences were found in gestational age at delivery, neonatal weight, premature rupture of membranes or pregnancy loss. The relative risk of pregnancy-induced hypertension in the study group was 0.29 (p < 0.01) and that of gestational diabetes was 0.3 (p < 0.05). Only when low MShCG was associated with a high or low MSAFP or low MSuE3 was there a significantly increased loss of pregnancy (relative risk 11.7; p < 0.0001). The data suggest that second-trimester MShCG < 0.4 MoM by itself has no influence on the outcome of pregnancy.