Placental sonolucency and pregnancy outcome in women with elevated second trimester serum alpha-fetoprotein levels.

BACKGROUND AND PURPOSE: Women with unexplained elevation of serum alpha-fetoprotein (AFP) are at increased risk for adverse pregnancy outcomes, including small for gestational age neonate, preterm labor, abruptio placentae, preeclampsia, intrauterine fetal death, and congenital malformations. This study investigated the association between placental sonolucency, elevation of maternal serum AFP, and pregnancy outcomes. METHODS: Singleton pregnancies (n = 168) with second trimester serum AFP level >/= 2.0 weight-adjusted multiples of the median (MoM) were recruited as the study group. Women with second trimester serum AFP level between 0.4 and 2.0 weight-adjusted MoM (n = 150) served as controls. A maternal Kleihauer-Betke stain was obtained for all participants. All participants were prospectively evaluated and the pregnancy complications were assessed by chart analysis after delivery. RESULTS: Compared with control subjects, women with placental sonolucent areas were not at increased risk for pregnancy complications, while women without sonolucent areas had higher risk of pregnancy complications. Singleton pregnancies with elevated serum AFP level had increased incidence of feto-maternal hemorrhage when placental sonolucency was observed. CONCLUSIONS: Our data suggest that feto-maternal hemorrhage may be the major factor contributing to elevated maternal serum AFP levels in pregnancies carrying placental sonolucencies. Screening for pregnancies with both elevated serum AFP and placental sonolucencies would help to identify the low-risk cases and facilitate cost-effective obstetric management.     

The significance of raised maternal serum alpha-fetoprotein levels.

A radioimmunoassay for alpha-fetoprotein (AFP) is described and normal ranges for both maternal serum and in amniotic fluid throughout pregnancy are defined. Maternal serum AFP levels in at risk pregnancies were found to be no different from those in normal pregnancies. AFP levels in pregnancies complicated by neural tube and other congenital defects, fetal death or maternal hypertension are documented. Eight patients with a fetus deformed by anencephaly or an open spina bifida were tested before 22 weeks; seven of them had raised serum AFP levels. Other causes of raised serum AFP levels are described and the significance of a raised serum AFP level is discussed with particular reference to screening programmes.     

Three-dimensional ultrasound measurement of the placental volume in early pregnancy: method and correlation with biochemical placenta parameters.

Placental size has been an interesting topic of research for many years. The main aim of this study was to investigate the feasibility of measuring the placental volume at the end of the first trimester using three-dimensional (3D) ultrasound and to correlate these volumes to known placental functional indices and to factors affecting the placenta. Women with singleton pregnancies at the end of the first trimester were included into this study. The volume data of the placentae were correlated to the crown-rump length (CRL), placenta-associated plasma protein A (PAPP-A), free beta-human chroangiogonadotropin (f-beta-hCG) and other factors that may affect the placental size or function. A total of 1462 pregnancies could be evaluated. Comparison between CRL and placental volume proved a significant correlation (r=0.43, P< 0.001). Due to the observed proportional growth of CRL and placental volume, a quotient (placental volume/CRL) was calculated for each case. There were no differences between placenta/CRL-quotients in relation to gravidity, parity or smoking. Correlations could be established between the placental volume and PAPP-A and f-beta-hCG (PAPP-A: r=0.28, P< 0.001, f-beta-hCG: r=0.10, P< 0.001). The measurement of the placenta in the first trimester can be performed in a high percentage of cases. The placenta/CRL quotient represents a simple method to compare placentae from different gestational days. The correlation between placental volume and maternal serum screening parameters might provide a chance to refine first trimester Down's syndrome serum screening. Future studies will be needed to evaluate the possible clinical use of first trimester placental volume measurements.     

Prediction of fetal outcome in threatened abortion by maternal serum placental lactogen and alpha fetoprotein.

Abnormally low human placental lactogen (HPL) or high alpha fetoprotein (AFP) levels in maternal serum are unfavorable prognostic signs in women with threatened abortion but normal levels cannot be used to discriminate between viable and nonviable pregnancies. Out of 112 women with threatened abortion, 69 aborted; of these, 36 had a low HPL level and they all aborted. Five women had an increased AFP concentration. Four of these aborted and the remaining case was a twin pregnancy in which one fetus died and the other survived. HPL and AFP levels provide complementary information as to the fetal outcome in threatened abortion. This was indicated by a normal HPL level in all of the five cases with raised maternal AFP, and by a normal AFP level in 35 of the 36 women with low maternal HPL.     

Pregnancy associated plasma protein-A2: A novel biomarker for down syndrome

IntroductionIn an effort to improve prenatal screening for Trisomy 21, we evaluated pregnancy associated plasma protein-A2 (PAPP-A2) as a potential novel second trimester biomarker for Trisomy 21.MethodsTrisomy 21 and normal control mid-trimester placental samples were subjected to quantitative rt PCR analysis of seven genes we had previously found to be differentially expressed in Trisomy 21 placentae. The localization and differential expression of PAPP-A2 in second trimester placentae from normal and Trisomy 21 pregnancies was determined by immunohistochemistry. PAPP-A2 maternal serum protein levels in ten Trisomy 21 and ten diploid pregnancies were compared by Western blotting. Maternal serum PAPP-A2 levels were measured in 30 Down syndrome cases and 142 normal controls, using ELISA. Regression analysis was used to determine the correlation of PAPP-A2 with other existing markers of Trisomy 21.ResultsPAPP-A2 (aka PLAC 3) mRNA and protein expression were both increased in Down syndrome placentae as compared to diploid placentae. PAPP-A2 was also increased in maternal serum from Down syndrome pregnancies as compared to diploid pregnancies. PAPP-A2 expression correlated weakly with established markers.DiscussionThis work takes advantage of our previously performed systematic approach to the discovery of novel maternal serum biomarkers for Trisomy 21, using cDNA microarray analysis. Beginning with the validation of the microarray results, we have tracked PAPP-A2 overexpression in Down syndrome from placental mRNA to maternal serum protein.ConclusionPAPP-A2 could serve as an additional maternal serum marker in prenatal screening for Trisomy 21.     

Maternal serum alpha-fetoprotein and low birth weight in relation to gestational age

To determine when in the first and second trimester a raised serum alpha-fetoprotein (AFP) level best predicts low birth weight a case-control study was performed on 157 singleton low birth-weight (less than or equal to 2.5 kg) and 314 singleton control pregnancies (birth weight greater than 2.5 kg). The association between raised maternal serum AFP and low birth weight was confirmed, but there was no special time in pregnancy before 29 weeks gestation when a raised AFP level predicted low birth weight materially better than at any other time.     

Maternal serum α-fetoprotein and low birth weight in relation to gestational age

Summary. To determine when in the first and second trimester a raised serum α-fetoprotein (AFP) level best predicts low birth weight a case-control study was performed on 157 singleton low birth-weight (2.5 kg) and 314 singleton control pregnancies (birth weight >2.5 kg). The association between raised maternal serum AFP and low birth weight was confirmed, but there was no special time in pregnancy before 29 weeks gestation when a raised AFP level predicted low birth weight materially better than at any other time.     

Relative abundance of placental pro-atrial natriuretic factor mRNA in normal pregnancy and pre-eclampsia

Atrial natriuretic factor (ANF), produced by cytotrophoblast cells of the human placenta, may be involved in the regulation of uteroplacental blood flow. Pre-eclampsia is associated with maternal hypertension and reduced uteroplacental perfusion. The relationship between pre-eclampsia and placental production of ANF is not known. This study measured pro-ANF mRNA levels by Northern blot analysis in placentae delivered by caesarean section at preterm and term gestations from women with normotensive and pre-eclamptic pregnancies and found no significant difference between pre-eclampsia and normal pregnancy at either gestation. This result suggests that placental production of ANF is not altered at the pretranslational level during pre-eclampsia.     

Alpha-fetoprotein levels in placenta, maternal, and cord blood in normal and pathologic pregnancy.

The level of placental alpha-fetoprotein (AFP) in normal pregnancy at term was found to be 5050 +/- ng/g fresh tissue. A significant increase was noted in the toxemic placenta associated with a rise in circulating maternal AFP level and a nonsignificant increase in cord blood. The increase in maternal AFP level in cases of premature delivery before 33 weeks' gestation and postmature delivery after 40 weeks' gestation predicted that maternal AFP measurement throughout the second and third trimester of pregnancy could be clinically established as an index of placental function.     

Vitamin A concentration in amniotic fluid and maternal serum related to neural-tube defects

The vitamin A concentration of amniotic fluid and maternal serum was measured during the second trimester of pregnancy in 106 women, 12 of whom had a baby with a neural-tube defect. In these 12 pregnancies the amniotic fluid vitamin A concentration was significantly higher than in 94 normal pregnancies. There was a highly significant correlation between amniotic fluid vitamin A and both zinc and alpha-fetoprotein (AFP) levels. The maternal serum vitamin A levels were also significantly related to serum zinc levels. Women with a raised serum AFP level, but a normal baby, had significantly higher amniotic fluid vitamin A levels and significantly lower serum vitamin A levels compared with those in women with normal serum AFP levels.     

Prenatal diagnosis of spina bifida aperta after first-trimester valproate exposure.

In the context of a prospective study on the adverse effects of anti-epileptic drugs on fetal outcome, we evaluated our experience with prenatal diagnosis by ultrasonography and alpha-fetoprotein (AFP) determination in amniotic fluid. We compared these results with AFP values in maternal serum obtained prior to amniocentesis. From November 1985 to July 1990, amniocentesis at 16-18 weeks of gestation was performed in 267 pregnancies of 237 different women using anti-epileptic drugs. Among 92 pregnancies with maternal valproic acid use, five (including one concordantly affected monozygotic twin-pair) were terminated because of a spina bifida aperta, all prenatally diagnosed by AFP determination and acetylcholinesterase electrophoresis in amniotic fluid. The maternal serum AFP level was raised (> or = 2.5 multiples of the median (MOM) for singleton pregnancies and > or = 4.5 MOM for twin pregnancies) in only two of these five affected pregnancies. We emphasize that maternal serum AFP levels may be unreliable for prenatal screening for fetal neural tube defects in women taking valproate and recommend that amniocentesis and fetal ultrasound examination should be offered directly.     

Antenatal screening for congenital nephrosis in Finland by maternal serum α-fetoprotein

Summary. In the Kuopio and North-Karelia districts of Finland 10 724 pregnancies were screened for congenital nephrosis by maternal serum AL-fetoprotein (AFP) measurement. Outcome was known for 10 504 (98%) pregnancies, of which 509 (4.8%) had a serum AFP level ≤ 2.5 multiples of the normal median (MoM) at 15–18 weeks gestation. After exclusion of those women who had a normal serum AFP level (< 2.5 MoM) in a second sample,'wrong dates'or multiple pregnancy, 267 (2.5%) remained with a high serum AFP level. Amniocentesis was carried out in 225 (2.1%) and 16 women had an amniotic fluid AFP level > 10 SD above the normal mean. In this group there were six fetuses with congenital nephrosis (four confirmed and two suspected), six other serious malformations (including an intrauterine death) and four without obvious abnormality. In the 98% pregnancies followed up there were no infants with congenital nephrosis that had been missed. Babies with congenital nephrosis require permanent hospitalization and have a mean survival of 8 months. In Finland, within certain areas, the birth prevalence is as high as 1 in 2600 per year. In such areas maternal serum AFP measurement appears to be a useful method of screening for congenital nephrosis. The service was also well accepted since 94% of the women with raised serum AFP levels wished to be screened again in a future pregnancy.     

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.     

Vitamin A concentration in amniotic fluid and maternal serum related to neural-tube defects

Summary. The vitamin A concentration of amniotic fluid and maternal serum was measured during the second trimester of pregnancy in 106 women, 12 of whom had a baby with a neural-tube defect. In these 12 pregnancies the amniotic fluid vitamin A concentration was significantly higher than in 94 normal pregnancies. There was a highly significant correlation between amniotic fluid vitamin A and both zinc and α-fetoprotein (AFP) levels. The maternal serum vitamin A levels were also significantly related to serum zinc levels. Women with a raised serum AFP level, but a normal baby, had significantly higher amniotic fluid vitamin A levels and significantly lower serum vitamin A levels compared with those in women with normal serum AFP levels.     

Antenatal screening for congenital nephrosis in Finland by maternal serum alpha-fetoprotein

In the Kuopio and North-Karelia districts of Finland 10724 pregnancies were screened for congenital nephrosis by maternal serum alpha-fetoprotein (AFP) measurement. Outcome was known for 10504 (98%) pregnancies, of which 509 (4 X 8%) had a serum AFP level greater than or equal to 2 X 5 multiples of the normal median (MoM) at 15-18 weeks gestation. After exclusion of those women who had a normal serum AFP level (less than 2 X 5 MoM) in a second sample, 'wrong dates' or multiple pregnancy, 267 (2 X 5%) remained with a high serum AFP level. Amniocentesis was carried out in 225 (2 X 1%) and 16 women had an amniotic fluid AFP level greater than 10 SD above the normal mean. In this group there were six fetuses with congenital nephrosis (four confirmed and two suspected), six other serious malformations (including an intrauterine death) and four without obvious abnormality. In the 98% pregnancies followed up there were no infants with congenital nephrosis that had been missed. Babies with congenital nephrosis require permanent hospitalization and have a mean survival of 8 months. In Finland, within certain areas, the birth prevalence is as high as 1 in 2600 per year. In such areas maternal serum AFP measurement appears to be a useful method of screening for congenital nephrosis. The service was also well accepted since 94% of the women with raised serum AFP levels wished to be screened again in a future pregnancy.     

Estimating a woman's risk of having a pregnancy associated with Down's syndrome using her age and serum alpha-fetoprotein level

The risk of an individual woman having a pregnancy associated with Down's syndrome was estimated from her age and her serum alpha-fetoprotein (AFP) level at 14-20 weeks gestation. The estimates were made using published data on the risk of Down's syndrome in relation to maternal age from 4528 affected and over 5 million unaffected pregnancies, and on the risk in relation to serum AFP from 68 affected and 36,645 unaffected pregnancies. Separate estimates were derived for AFP levels using gestational age based on the time since the first day of the last menstrual period and on an ultrasound biparietal diameter measurement. In each case this was done with and without adjusting AFP levels to take account of maternal weight. The same sources of data were also used to construct six Down's syndrome screening policies, each combining information on maternal age and serum AFP. For example with one policy the detection rate would be 28% and would involve selecting 2.8% of unaffected pregnancies for amniocentesis; using age alone the same detection rate could only be achieved by selecting 4.3% of unaffected pregnancies for amniocentesis--an increase of 50%. In general, screening for Down's syndrome using both maternal age and serum AFP is more efficient than either alone.     

Placental growth from the first to the second trimester of pregnancy in SGA-foetuses and pre-eclamptic pregnancies compared to normal foetuses

The aim of this study was to determine placental growth between 12-22 weeks in normal pregnancies compared to pregnancies complicated by foetal SGA and maternal pre-eclampsia (PE). The placentae of 1199 women were measured 3D sonographically at 12, 16 and 22 weeks of gestation. Placental volume growth was then calculated. Neonatal birthweight, birth centile and the occurrence of pre-eclampsia were recorded in every woman and correlated with placental growth (four groups: normals, SGA, PE, SGA+PE). SGA-placentae are already smaller at 12 weeks but then develop in a similar way to normal placentae. PE placentae are slightly, but significantly, larger at 12 weeks, grow rapidly until 16 weeks and then stop growing normally between 16 and 22 weeks. If SGA goes together with PE, both placental volume (PV) at 12 weeks as well as growth is reduced significantly. Nevertheless, placental growth between week 12 and 22 is too heterogeneous to justify using this method as a clinical tool, but it can provide new information on placental physiology underlying unfavourable obstetric outcomes.     

Maternal serum second trimester AFP and hCG in pregnancies with placenta previa

This study was undertaken to investigate the association between placenta previa and Down syndrome screening analytes-alpha-fetoprotein (AFP) and hCG-during the second trimester. Measurements of maternal serum AFP and hCG concentrations were retrospectively analysed in relation to placenta previa in a cohort of 46 consecutive singleton pregnancies affected by placenta previa from January 1993 through December 1997 at the University Hospital of Kuopio, Finland, and then compared with those in healthy singleton control pregnancies (N=9560) from the same clinic over the same period of time. Geometric means of maternal serum AFP and hCG concentrations in pregnancies with placenta previa were 1.13 and 0. 85 multiples of the median (MoM), respectively. The mean maternal age was higher in the subjects than in the controls (30.9 years compared with 28.8 years) (p<0.01). In relation to Down syndrome risk assessment, the pattern of the two markers together with maternal age indicated high risk as often in the study subjects as in the controls. Even though the maternal serum AFP and hCG differences were not statistically significant, they may be of some clinical importance, and further studies are needed to evaluate whether placental site should be taken into account in maternal serum screening.     

Placental GPI-PLD is of maternal origin and its GPI substrate is absent from placentae of pregnancies associated with pre-eclampsia

Pre-eclampsia (PE) is a disorder affecting 5-10% of all pregnancies and is characterised by abnormal trophoblast invasion, maternal endothelial cell dysfunction and a systemic maternal response. A unifying factor responsible for eliciting these effects remains unknown. However, levels of the autocrine insulin mediators, inositolphosphoglycans (IPG), are elevated 3-fold in pre-eclamptic placentae compared with controls and are also elevated 3-fold in maternal urine of pre-eclamptic women, suggesting an abnormal paracrine role of the mediator in the systemic maternal response. At the placental level, IPGs are metabolic second messengers capable of eliciting some of the characteristic features of PE, such as the 10-fold increase in glycogen synthesis and 16-fold increase in the activity of the IPG-dependent enzyme glycogen synthase. IPGs are derived from their lipidic precursors, the glycosylphosphatidylinositols (GPI), in membrane associated caveolae by the action of a GPI-specific phospholipase D whose activity is regulated by its membrane microenvironment. We show that the lipidic GPI precursor was detected in total placental membrane and microvillous membrane from normal placentae. The presence of GPI could not be detected in PE placentae, suggesting that the GPI/IPG signalling system is dysregulated in this disorder. Equivalent amounts of a proteolytically-cleaved 50 kDa GPI-PLD protein is detected in both normal and PE placentae. However, GPI-PLD mRNA is absent, suggesting a mechanism of uptake from maternal serum. Since GPI-PLD, whose presence is required for hydrolysis of GPI and release of free IPG, is detectable with equal activity in both normal and PE placentae, we postulate that dysregulation of the tubular caveolar structure of the microvilli in pre-eclamptic placentae provides an environment which promotes the unregulated hydrolysis of GPI in this disorder.