Placental protein measurements in complicated pregnancies. I. Intrauterine growth retardation

Birth Weight < 3rd Percentile Prediction Using Additional Biochemical Markers-The Uric Acid Level and Angiogenesis Markers (sFlt-1, PlGF)-An Exploratory Study

(1) Aim: Ultrasound is the gold standard for assessing fetal growth disorders. The relationship between high sFlt-1/PlGF scores and LBW (low birth weight) was described. In this study, we attempted to assess whether uric acid could be used as a secondary marker in estimating the pregnancy risk associated with LBW. (2) Material and methods: 665 pregnant women with a suspected or confirmed form of placental insufficiency were enrolled. In each of the patients, sFlt-1 and PlGF and uric acid levels were determined. Patients were divided into two groups according to birth weight below and above the third percentile for the given gestational age with the criteria of the neonatal definition of FGR (fetal growth restriction). (3) Results: A significant negative correlation between neonatal birth weight and the uric acid level across the entire study group was observed. We found a significant negative correlation between neonatal birth weight and the uric acid level with birth weights < 3rd percentile. (4) Conclusions: There is a significant link between the uric acid concentration and LBW in the group with placental insufficiency. Uric acid can improve the prediction of LBW. An algorithm for LBW prognosis that makes use of biophysical (ultrasound) and biochemical (uric acid level, angiogenesis markers) parameters yields better results than using these parameters separately from each other.

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

A proteomic clock of human pregnancy

BACKGROUND

Early detection of maladaptive processes underlying pregnancy-related pathologies is desirable because it will enable targeted interventions ahead of clinical manifestations. The quantitative analysis of plasma proteins features prominently among molecular approaches used to detect deviations from normal pregnancy. However, derivation of proteomic signatures sufficiently predictive of pregnancy-related outcomes has been challenging. An important obstacle hindering such efforts were limitations in assay technology, which prevented the broad examination of the plasma proteome.

OBJECTIVE

The recent availability of a highly multiplexed platform affording the simultaneous measurement of 1310 plasma proteins opens the door for a more explorative approach. The major aim of this study was to examine whether analysis of plasma collected during gestation of term pregnancy would allow identifying a set of proteins that tightly track gestational age. Establishing precisely timed plasma proteomic changes during term pregnancy is a critical step in identifying deviations from regular patterns caused by fetal and maternal maladaptations. A second aim was to gain insight into functional attributes of identified proteins and link such attributes to relevant immunological changes.

STUDY DESIGN

Pregnant women participated in this longitudinal study. In 2 subsequent sets of 21 (training cohort) and 10 (validation cohort) women, specific blood specimens were collected during the first (7-14 weeks), second (15-20 weeks), and third (24-32 weeks) trimesters and 6 weeks postpartum for analysis with a highly multiplexed aptamer-based platform. An elastic net algorithm was applied to infer a proteomic model predicting gestational age. A bootstrapping procedure and piecewise regression analysis was used to extract the minimum number of proteins required for predicting gestational age without compromising predictive power. Gene ontology analysis was applied to infer enrichment of molecular functions among proteins included in the proteomic model. Changes in abundance of proteins with such functions were linked to immune features predictive of gestational age at the time of sampling in pregnancies delivering at term.

RESULTS

An independently validated model consisting of 74 proteins strongly predicted gestational age (P = 3.8 × 10^-14, R = 0.97). The model could be reduced to 8 proteins without losing its predictive power (P = 1.7 × 10^-3, R = 0.91). The 3 top ranked proteins were glypican 3, chorionic somatomammotropin hormone, and granulins. Proteins activating the Janus kinase and signal transducer and activator of transcription pathway were enriched in the proteomic model, chorionic somatomammotropin hormone being the top-ranked protein. Abundance of chorionic somatomammotropin hormone strongly correlated with signal transducer and activator of transcription-5 signaling activity in CD4 T cells, the endogenous cell-signaling event most predictive of gestational age.

CONCLUSION

Results indicate that precisely timed changes in the plasma proteome during term pregnancy mirror a proteomic clock. Importantly, the combined use of several plasma proteins was required for accurate prediction. The exciting promise of such a clock is that deviations from its regular chronological profile may assist in the early diagnoses of pregnancy-related pathologies, and point to underlying pathophysiology. Functional analysis of the proteomic model generated the novel hypothesis that chrionic somatomammotropin hormone may critically regulate T-cell function during pregnancy.

Novel biomarkers for predicting intrauterine growth restriction: a systematic review and meta-analysis

BACKGROUND

Several biomarkers for predicting intrauterine growth restriction (IUGR) have been proposed in recent years. However, the predictive performance of these biomarkers has not been systematically evaluated.

OBJECTIVE

To determine the predictive accuracy of novel biomarkers for IUGR in women with singleton gestations.

SEARCH STRATEGY

Electronic databases, reference list checking and conference proceedings.

SELECTION CRITERIA

Observational studies that evaluated the accuracy of novel biomarkers proposed for predicting IUGR.

DATA COLLECTION AND ANALYSIS

Data were extracted on characteristics, quality and predictive accuracy from each study to construct 2×2 tables. Summary receiver operating characteristic curves, sensitivities, specificities and likelihood ratios (LRs) were generated.

MAIN RESULTS

A total of 53 studies, including 39,974 women and evaluating 37 novel biomarkers, fulfilled the inclusion criteria. Overall, the predictive accuracy of angiogenic factors for IUGR was minimal (median pooled positive and negative LRs of 1.7, range 1.0-19.8; and 0.8, range 0.0-1.0, respectively). Two small case-control studies reported high predictive values for placental growth factor and angiopoietin-2 only when IUGR was defined as birthweight centile with clinical or pathological evidence of fetal growth restriction. Biomarkers related to endothelial function/oxidative stress, placental protein/hormone, and others such as serum levels of vitamin D, urinary albumin:creatinine ratio, thyroid function tests and metabolomic profile had low predictive accuracy.

CONCLUSIONS

None of the novel biomarkers evaluated in this review are sufficiently accurate to recommend their use as predictors of IUGR in routine clinical practice. However, the use of biomarkers in combination with biophysical parameters and maternal characteristics could be more useful and merits further research.

First trimester maternal serum pregnancy-specific beta-1-glycoprotein (SP1) as a marker of adverse pregnancy outcome

OBJECTIVE

To establish the first trimester levels of pregnancy-specific beta-1-glycoprotein (SP1) in pregnancies with adverse outcome. Furthermore, to determine the screening performance for adverse outcome using SP1 alone and in combination with other first trimester markers including proMBP and PAPP-A.

METHODS

A case-control study was conducted in a primary hospital setting. The SP1 concentration was measured in first trimester maternal serum in pregnancies with small-for-gestational age fetuses (SGA) (n = 150), spontaneous preterm delivery (n = 88), preeclampsia (n = 40) and in controls (n = 500). Concentrations were converted to multiples of the median (MoM) in controls and groups were compared using Mann-Whitney U-test. Logistic regression analysis was used to determine significant factors for predicting adverse pregnancy outcome. Screening performance was assessed using receiver operating characteristic (ROC) curves.

RESULTS

The SP1 MoM median was significantly reduced in cases with SGA (0.76 MoM, p < 0.0005) and spontaneous preterm delivery (0.77 MoM, p < 0.0005) whereas no alteration was found in cases with preeclampsia (0.94 MoM, p = 0.723). A significant correlation (r = 0.217) between log(10)(SP1 MoM) and the birth weight percentile was found in the SGA group. Screening performance was only slightly improved when SP1 was combined with PAPP-A or proMBP.

CONCLUSION

SP1 is a first trimester maternal serum marker of SGA and preterm delivery.

Serum screening with Down's syndrome markers to predict pre-eclampsia and small for gestational age: systematic review and meta-analysis

Background

Reliable antenatal identification of pre-eclampsia and small for gestational age is crucial to judicious allocation of monitoring resources and use of preventative treatment with the prospect of improving maternal/perinatal outcome. The purpose of this systematic review was to determine the accuracy of five serum analytes used in Down's serum screening for prediction of pre-eclampsia and/or small for gestational age.

Methods

The data sources included Medline, Embase, Cochrane library, Medion (inception to February 2007), hand searching of relevant journals, reference list checking of included articles, contact with experts. Two reviewers independently selected the articles in which the accuracy of an analyte used in Downs's serum screening before the 25^th gestational week was associated with the occurrence of pre-eclampsia and/or small for gestational age without language restrictions. Two authors independently extracted data on study characteristics, quality and results.

Results

Five serum screening markers were evaluated. 44 studies, testing 169,637 pregnant women (4376 pre-eclampsia cases) and 86 studies, testing 382,005 women (20,339 fetal growth restriction cases) met the selection criteria. The results showed low predictive accuracy overall. For pre-eclampsia the best predictor was inhibin A>2.79MoM positive likelihood ratio 19.52 (8.33,45.79) and negative likelihood ratio 0.30 (0.13,0.68) (single study). For small for gestational age it was AFP>2.0MoM to predict birth weight < 10^th centile with birth < 37 weeks positive likelihood ratio 27.96 (8.02,97.48) and negative likelihood ratio 0.78 (0.55,1.11) (single study). A potential clinical application using aspirin as a treatment is given as an example.

There were methodological and reporting limitations in the included studies thus studies were heterogeneous giving pooled results with wide confidence intervals.

Conclusion

Down's serum screening analytes have low predictive accuracy for pre-eclampsia and small for gestational age. They may be a useful means of risk assessment or of use in prediction when combined with other tests.

The expression of ovine placental lactogen, StAR and progesterone-associated steroidogenic enzymes in placentae of overnourished growing adolescent ewes

Overnourishing pregnant adolescent sheep promotes maternal growth but reduces placental mass, lamb birth weight and circulating progesterone. This study aimed to determine whether altered progesterone reflected transcript abundance for StAR (cholesterol transporter) and the steroidogenic enzymes (Cyp11A1, Hsd3b and Cyp17). Circulating and placental expression of ovine placental lactogen (oPL) was also investigated. Adolescent ewes with singleton pregnancies were fed high (H) or moderate (M) nutrient intake diets to restrict or support placental growth. Experiment 1: peripheral progesterone and oPL concentrations were measured in H (n=7) and M (n=6) animals across gestation (days 7-140). Experiment 2: progesterone was measured to mid- (day 81; M: n=11, H: n=13) or late gestation (day 130; M: n=21, H: n=22), placental oPL, StAR and steroidogenic enzymes were measured by qPCR and oPL protein by immunohistochemistry. Experiment 1: in H vs M animals, term placental (P<0.05), total cotyledon (P<0.01) and foetal size (P<0.05) were reduced. Circulating oPL and progesterone were reduced at mid- (P<0.001, P<0.01) and late gestation (P<0.01, P<0.05) and oPL detection was delayed (P<0.01). Experiment 2: placental oPL was not altered by nutrition. In day 81 H animals, progesterone levels were reduced (P<0.001) but not related to placental or foetal size. Moreover, placental steroidogenic enzymes were unaffected. Day 130 progesterone (P<0.001) and Cyp11A1 (P<0.05) were reduced in H animals with intrauterine growth restriction (H+IUGR). Reduced mid-gestation peripheral oPL and progesterone may reflect altered placental differentiation and/or increased hepatic clearance respectively. Restricted placental growth and reduced biosynthesis may account for reduced progesterone in day 130 H+IUGR ewes.

Predictive value of hormone measurements in maternal and fetal complications of pregnancy

Intrauterine tissues (placenta, amnion, chorion, decidua) express hormones and cytokines that play a decisive role in maternal-fetal physiological interactions. The excessive or deficient release of some placental hormones in association with gestational diseases may reflect an abnormal differentiation of the placenta, an impaired fetal metabolism, or an adaptive response of the feto-placental unit to adverse conditions. This review is focused on the applicability of hormone measurements in the risk assessment, early diagnosis, and management of pregnancies complicated by Down's syndrome, fetal growth restriction, preeclampsia, preterm delivery, and diabetes mellitus. Combined hormonal tests or the combination of hormones and ultrasound may achieve reasonable sensitivity, but research continues to simplify the screening programs without sacrificing their accuracy. Only in a few instances is there sufficient evidence to firmly recommend the routine use of hormone tests to predict maternal and fetal complications, but the judicious use of selected tests may enhance the sensitivity of the risk assessment based solely on clinical and ultrasound examination.

Serial measurements of serum human placental lactogen (hPL) and serial ultrasound examinations in the evaluation of fetal growth

Serial serum hPL measurements and serial ultrasound fetometry were compared in the evaluation of fetal growth by relating these two parameters to size at birth and to clinical factors known to influence size at birth. The data were from a prospective study of 1000 consecutive pregnant women considered to be at risk for fetal growth retardation with retrospective analysis. Serum hPL was measured by radioimmunoassay and fetal weight estimated by ultrasound every 3 weeks during the last trimester. hPL values were expressed as multiples of the median (MoM) and linear regression analysis of the hPL MoM values was carried out for each pregnancy to find the slope of the line (hPL-slope); at least 3 serum hPL values were required. The estimated fetal weight and weight-for-age at birth was expressed in Z-scores. The individual intrauterine growth velocity was calculated by regression analysis and expressed as change in Z-score for 12 weeks. At least two ultrasound measurements over an interval of at least 42 days were used to estimate the fetal growth velocity. In 588 women the file was complete. The main outcome measures were the individual mean hPL, hPL-slope, fetal growth velocity, birth weight deviation, smoking in pregnancy and diagnosis of preeclampsia. A significant correlation was found between the hPL-slope and the intrauterine fetal growth velocity (r=0.34), and between hPL-slope and birth weight deviation (r=0.32). Mean hPL was correlated to birth weight deviation (r=0.27), but only very weakly to intrauterine growth velocity (r=0.08). hPL-slope and intrauterine growth velocity independently predicted birth weight deviation. Heavy smoking which was stopped before the third trimester was not associated with low intrauterine growth velocity, but with a low hPL-slope. Preeclampsia was associated with a trend towards low and decreasing hPL and with an increasing intrauterine growth velocity and birth weight deviation. In conclusion the rate of change of serial hPL measurements correlated well to intrauterine fetal growth velocity in the third trimester as estimated by ultrasound and to the deviation in birth weight, but hPL seems to have a separate physiological significance, since it did not pick up when smoking was stopped and growth velocity was normalised and it did not at all detect the increased growth associated with preeclampsia.

Maternal serum levels of free beta-hCG and PAPP-A in the first trimester of pregnancy are not associated with subsequent fetal growth retardation or preterm delivery

The purpose of this case-control study was to examine the association of first-trimester concentrations of free beta-human chorionic gonadotropin (free beta-hCG) and pregnancy-associated plasma protein A (PAPP-A) in maternal serum with subsequent preterm delivery or small-for-gestational age (SGA) fetuses. We collected all the blood samples before chorionic villus sampling in the first trimester. Concentrations of free beta-hCG and PAPP-A were expressed in multiples of the median (MOM) for gestational age. We compared the levels of both analytes in 73 SGA pregnancies (birth weight below the fifth percentile) with those in 292 normal controls, who were matched for gestational age, maternal age, parity, maternal weight, and smoking habits. We also compared the levels in 87 pregnancies with a preterm delivery (delivery before 37 completed weeks) with those in 348 matched controls. The median concentrations of PAPP-A and free beta-hCG, expressed in MOMs, in the 73 SGA pregnancies were 0.83 and 0.95, respectively, compared with 0.98 and 1.01, respectively, in the 292 matched controls (P=0.08 and 0.19, respectively). In the 87 pregnancies with a preterm delivery, the median concentrations of PAPP-A and free beta-hCG were 0.98 and 0.94, respectively, compared with 0.99 and 0.99, respectively, in the 348 matched controls (P=0.82 and 0.10, respectively). In contrast with the maternal serum analytes used in second-trimester screening--alpha-fetoprotein and human chorionic gonadotropin--this study showed that concentrations of PAPP-A and free beta-hCG in the first trimester were not associated with subsequent fetal growth retardation or preterm delivery.

Fenoterol increases erythropoietin concentrations during tocolysis

AIMS

The present study was carried out to assess the effect of the selective beta2-adrenoceptor agonists on erythropoietin (EPO) production.

METHODS

Routine tocolysis with fenoterol (using the regular rate of 2 microg min[-1]) was used as a clinically easily accessible model.

RESULTS

EPO concentrations had doubled 24 h after the start of tocolysis (P < 0.001). This increase lasted over the entire observation period of 48 h. Potassium concentrations fell significantly during the first hours of fenoterol infusion. There was no increase of human placenta lactogen during the period of EPO increase.

CONCLUSIONS

The data confirm our earlier results that fenoterol increases EPO concentrations following haemorrhage. In this model it was not necessary to stimulate EPO production prior to pharmacological treatment.

Placental isoferritin in pregnancies with small-for-gestational age fetuses

The secretion of placental isoferritin (PLF) during pregnancy could be responsible for the diminished immunoreaction of maternal lymphocytes against the embryo. In this study, serum levels of PLF in 335 pregnant women were correlated with birth weight, percentile of birth weight, gestational age, and pulsatility index of the uterine artery, as well as with diastolic notching. Women with small-for-gestational age (SGA) infants (birth weight below or equal to the tenth percentile) showed significantly lower PLF levels (11.7 U/ml) compared with women whose newborns were of normal weight (19.4 U/ml) (P < 0.05). In line with this finding, a strong correlation was observed between PLF levels and the percentile of birth weight, pulsatility index of the uterine artery, and the presence of diastolic notching. The strong correlation of low PLF values and SGA newborns suggests that determination of PLF could serve as a marker to identify women at risk of having such babies.

The efficacy of biochemical assays in assessing an IUGR risk-group, preselected with ultrasound fetometry

Dehydroepiandrosterone sulphate, progesterone, estradiol, estriol and human placental lactogen (hPL) were biochemically assayed in a group of 92 pregnancies in which intra-uterine growth retardation was suspected. The group was selected with ultrasound fetometry at 32 weeks of gestation, and maternal blood was sampled at 33, 35, 37 and 39 weeks of gestation. The IUGR group consisted of 30 pregnancies resulting in the birth of an infant with a birthweight of 2 standard deviations or more below the mean for gestational age in the Malmö population. Intra-uterine growth trends were defined by serial ultrasound fetometry performed every second week. Both serum hormone and hPL content were examined in relation to birth-weight, occurrence of imminent asphyxia at delivery, Apgar score, and pH in the umbilical vein. Neither dehydroepiandrosterone sulphate, nor progesterone nor estradiol values correlated to any of the outcome variables. To some extent estriol values distinguished IUGR from non-IUGR fetuses but not until the 39th gestational week, whereas hPL was effective in this respect in all weeks studied. An hPL value below 4 mg/l predicted IUGR with a sensitivity ranging from 52% to 74%, and a specificity ranging from 85% to 78%. HPL correlated well with the subsequent intra-uterine growth rate, but not with the outcome variables studied.

Complement activation, circulating protease inhibitors and pregnancy-associated proteins in severe pre-eclampsia

Circulating protease inhibitors, pregnancy-associated proteins and the split product of complement factor 3 (C3d) were measured in 14 women with severe pre-eclampsia and their matched controls. Only the mean levels of antithrombin III were observed to be significantly lower in pre-eclampsia (P less than 0.02).

Estimation of gestational age by last menstrual period, by ultrasound scan and by SP1 concentration: comparisons with date of delivery

The date of delivery in 62 normal pregnant women was predicted by last menstrual period, by ultrasound scan and by the serum concentration of Schwangerschaftsprotein 1 (SP1). It was found that SP1 concentration in the first trimester gave as reliable an indication of when labour would occur as did the last menstrual period or ultrasound scan.

Placental protein and hormone measurements in twin pregnancy

Maternal serum levels of human placental lactogen (hPL), schwangerschaftsprotein 1 (SP1), pregnancy-associated plasma protein A (PAPP-A), placental protein 5 (PP5) and total oestriol (E3) were measured serially in 35 twin pregnancies during the third trimester. Eighteen pregnancies had major complications including dysmaturity of one or both fetuses in nine, premature labour in six, and placental abruption in three. Serum levels of all five variables were higher than in singletons, this distinction being greatest for hPL and lowest for SP1 and E3. The levels of hPL, PP5 and E3 just before delivery were significantly correlated with the total birthweight, a correlation with placental weight being evident only for hPL and PP5. A significant correlation between the five biochemical variables at 33-34 weeks was only seen between hPL and PAPP-A. Protein and hormone levels in the abnormal twin pregnancies were not apparently different from those in the normal twin pregnancies. These data suggest that only hPL levels biochemically reflect this extreme of fetal and placental growth, but that neither the levels of hPL nor any of the other biochemical indices examined are altered in abnormalities in twin pregnancy.

Placental protein measurements in complicated pregnancies. III. Premature labour

Maternal serum levels of pregnancy-associated plasma protein. A (PAPP-A), human placental lactogen (hPL) and schwangerschafts-protein 1 (SP1) were measured serially during second and third trimester in 753 women with normal pregnancy when they were recruited to the study. In 24 women spontaneous premature labour occurred before 37 completed weeks and these women had significantly lower mean levels of serum SP1 at 29-31 weeks and at 33-34 weeks gestations but similar mean levels of serum PAPP-A and hPL at all gestations compared with corresponding values in normal pregnancy. The predictive value of an abnormal SP1 result was 5.2% at 29-31 weeks and 10.3% at 33-34 weeks. Furthermore, trends of levels of the three placental proteins in individual patients were similar to those seen in normal pregnancy, and the trends were unrelated to the occurrence of other complications and the time of onset of labour. This study suggests that measurements of the three placental proteins are unlikely to be of any value in the prediction of spontaneous premature labour.

Placental protein measurements in complicated pregnancies. II. Pregnancy-related hypertension

Maternal serum levels of pregnancy-associated plasma protein A (PAPP-A), human placental lactogen (hPL) and schwangerschafts-protein 1 (SP1) were measured serially during the second and third trimesters in 753 women with a normal pregnancy when recruited during the second trimester. Thirty-seven pregnancies were complicated by pregnancy-related hypertension after 28 weeks gestation. Maternal levels of PAPP-A and SP1, and trends of levels in individual patients, could generally not be distinguished from those seen in patients with a normal pregnancy, and were unrelated to the time of onset of the disease, its severity or the occurrence of other complications with one exception, in which decreased levels of SP1 and hPL were seen. Mean levels of hPL were significantly lower (P less than 0.05) at 35 weeks gestation. These data suggest that the measurement of the placental proteins examined here is of no value in the prediction of occurrence of pregnancy-related hypertension.