Low maternal serum levels of pregnancy associated plasma protein A (PAPP-A) in the first trimester in association with abnormal fetal karyotype

OBJECTIVE

To assess the relation between maternal serum pregnancy associated plasma protein A (PAPP-A) in the first trimester and the outcome of pregnancy by karyotype.

DESIGN

A retrospective study of PAPP-A levels in blood samples collected prior to chorionic villus sampling.

SETTING

Milan, Italy.

SUBJECTS

Five hundred twenty-two women aged 20 to 47, at 7 to 11 weeks gestation, prior to undergoing chorionic villus sampling. Four hundred forty-five women had a pregnancy with a normal karyotype; in 30 pregnancies the karyotype was abnormal (including 14 cases of Down's syndrome and 7 of trisomy 18).

MAIN OUTCOME MEASURES

Normal or abnormal fetal karyotype. Serum PAPP-A at 6 to 11 weeks gestation measured by radioimmunoassay.

RESULTS

The median value of PAPP-A in the abnormal group was 0.27 multiples of the normal median (MoM). This is significantly lower than the median value in the normal group (1.01 MoM) (95% CI for the difference 0.46-0.84 MoM; P < 0.00001 Mann-Whitney test).

CONCLUSIONS

There is an association between low levels of PAPP-A in the first trimester with chromosome anomalies. Screening by measurement of PAPP-A might detect 60% of cases of Down's syndrome in the first trimester with a false positive rate of 5%.

Is luteal function maintained by factors other than chorionic gonadotrophin in early pregnancy?

Women with ectopic pregnancy (n = 14) and early embryonic arrest ('blighted ovum') (n = 9) were studied 16 days after conception, at a time when they were asymptomatic and serum concentrations of beta-human chorionic gonadotrophin (HCG) were in the normal range and increasing at an apparently normal rate. Serum progesterone and oestradiol concentrations were compared with those from normal women matched for gestational age and serum beta-HCG concentration whose singleton intra-uterine pregnancies proceeded normally beyond 20 weeks. Mean serum progesterone concentrations were significantly lower in the women with ectopic pregnancies than in matched controls (P < 0.002); however, there was no difference in the serum progesterone concentrations between women with blighted ova and matched controls. Statistically significant differences were not seen in serum oestradiol concentrations between either group and matched controls. Similarly there was no difference in serum progesterone or oestradiol concentrations in 20 women who conceived ectopic pregnancies and 20 women conceiving blighted ovum pregnancies and their matched intra-uterine controls when conception followed ovarian stimulation. The low serum progesterone concentrations seen in ectopic pregnancy suggest that there is a specific and selective deficiency in progesterone synthesis, which implies that factors other than HCG may influence luteal function.

The role of trophoblast dysfunction in the aetiology of miscarriage

OBJECTIVE

To investigate the endocrine changes associated with spontaneous miscarriage after fetal heart activity has been demonstrated.

DESIGN

Prospective study during the first trimester of pregnancy comparing the circulating levels of human chorionic gonadotrophin (hCG), Schwangerschaft protein 1 (SP-1), pregnancy-associated plasma protein A (PAPP-A), oestradiol (E2), and progesterone (P), and fetal growth (crown-rump length [CRL] and gestational sac volume [GSV]) in women who miscarried after the identification of fetal heart activity with those of normal singleton and twin pregnancies achieved following in vitro fertilisation (IVF) and embryo transfer (ET).

SETTING

The Assisted Conception Unit of King's College Hospital, London.

SUBJECTS

Nine women who miscarried after demonstration of fetal heart activity, 52 normal singleton and 22 normal twin pregnancies.

INTERVENTIONS

Weekly blood tests and ultrasound assessments of CRL and GSV.

RESULTS

Four fetuses (all singleton) died between 9 and 12 weeks gestation (Group 1), and seven (three singleton and two twin) died between 16 and 20 weeks gestation (Group 2). In Group 1, both fetal growth and placental function, as assessed by serial measurements of CRL and GSV, and of serum levels of PAPP-A, SP-1 and hCG respectively, were reduced before fetal death. In Group 2, while fetal growth was maintained in all but one case, placental function was reduced in 4 of 5 women.

CONCLUSION

These findings suggest that there may be a relationship between trophoblast dysfunction and some forms of miscarriage. Furthermore, the pattern of the reduction in the circulating levels of the placental proteins in later miscarriages suggests that the function of specific cell types may be impaired.

Predicting fetal chromosome anomalies in the first trimester using pregnancy associated plasma protein-A: a comparison of statistical methods

The analysis of the clinical efficiency of a biochemical parameter in the prediction of chromosome anomalies is described, using a database of 475 cases including 30 abnormalities. A comparison was made of two different approaches to the statistical analysis: the use of Gaussian frequency distributions and likelihood ratios, and logistic regression. Both methods computed that for a 5% false-positive rate approximately 60% of anomalies are detected on the basis of maternal age and serum PAPP-A. The logistic regression analysis is appropriate where the outcome variable (chromosome anomaly) is binary and the detection rates refer to the original data only. The likelihood ratio method is used to predict the outcome in the general population. The latter method depends on the data or some transformation of the data fitting a known frequency distribution (Gaussian in this case). The precision of the predicted detection rates is limited by the small sample of abnormals (30 cases). Varying the means and standard deviations (to the limits of their 95% confidence intervals) of the fitted log Gaussian distributions resulted in a detection rate varying between 42% and 79% for a 5% false-positive rate. Thus, although the likelihood ratio method is potentially the better method in determining the usefulness of a test in the general population, larger numbers of abnormal cases are required to stabilise the means and standard deviations of the fitted log Gaussian distributions.

Serum placental protein 14 concentrations in the first trimester of ovum donation pregnancies

The concentration of the endometrial glycoprotein placental protein 14 (PP14) has been measured at weekly intervals during the first trimester in serum obtained from women who had become pregnant naturally (n = 15, all singleton) or following ovum donation (n = 16, 15 singleton and one twin) after ovarian failure (n = 13), Turner's syndrome (n = 2) or post-chemotherapy (n = 1). The concentration of PP14 failed to rise in ovum donation pregnancies, and was significantly reduced compared to the concentration in natural conceptions from 5 to 13 weeks gestation (P < 0.05-0.01). These findings demonstrate that the corpus luteum is essential for the normal increase in serum PP14 in the first trimester. Furthermore, they suggest that progesterone is not the major stimulus to PP14 synthesis in early pregnancy.

Circulating placental protein 14: in the first trimester of spontaneous and IVF pregnancies

Circulating placental protein 14 (PP14) levels were measured during the first trimester in three groups of pregnant women: (i) natural conception (n = 15); (ii) pituitary desensitization with buserelin and ovarian stimulation with human menopausal gonadotrophin (HMG) followed by in-vitro fertilization and embryo transfer (IVF-ET) (n = 15); and (iii) ovarian stimulation with clomiphene citrate and HMG, followed by IVF-ET (n = 16). A 7- to 8-fold increase in serum PP14 levels was observed in normal pregnancies between weeks 4 and 10. This increase was earlier and less marked in group (ii) and absent in group (iii). These findings support the concept that endometrial function is altered in pregnancies achieved following ovarian stimulation. Alternatively, if the ovary is an important source of PP14, then these data suggest that in contrast to ovarian synthesis of steroids and the peptide relaxin, ovarian stimulation results in an impairment of PP14 synthesis, and that this is most marked when clomiphene citrate has been used.

Endocrinology of in-vitro fertilization pregnancies during the first trimester

The endocrine function of the corpus luteum and placenta and the inter-relationships between ovarian steroids and the placental proteins in pregnancies achieved following ovarian stimulation, in-vitro fertilization and embryo transfer (IVF-ET) have been investigated. The serum concentrations of human chorionic gonadotrophin (HCG), Schwangerschaft protein-1 (SP-1), pregnancy-associated plasma protein A (PAPP-A), progesterone and oestradiol were measured at weekly intervals between the 4th (ET plus 2 weeks) and 14th week of gestation in 86 pregnancies. The mean concentrations of the placental proteins and oestradiol were significantly higher in twin than in singleton pregnancies from as early as 5 weeks gestation, but the mean concentrations of progesterone were significantly higher only at the end of the first trimester. Ranking, as demonstrated by the presence of statistically significant correlations between serum levels of each substance analysed in week 13 with those of preceding weeks, was established for progesterone and SP-1 from the 5th week, for oestradiol and PAPP-A from the 7th week and for HCG from the 8th week of gestation. The presence of statistically significant correlations between each substance analysed suggests that the placenta becomes the dominant source of oestradiol from 8 weeks gestation and of progesterone not until 12 weeks gestation, and that the placental synthesis of HCG, SP-1, PAPP-A, oestradiol and progesterone appear to be linked. There were no statistically significant correlations between the serum concentrations of HCG and either progesterone or oestradiol until the production of each had become predominantly placental.

Placental and ovarian hormones in anembryonic pregnancy

The circulating levels of human chorionic gonadotrophin (HCG), pregnancy-associated plasma protein-A (PAPP-A), Schwangerschaft protein 1 (SP-1), oestradiol and progesterone were measured in 81 pregnant patients between 4 and 11 weeks gestation, following in-vitro fertilization and embryo transfer. The patients were divided as follows: singleton anembryonic pregnancies, n = 22; singleton pregnancies which spontaneously aborted following the demonstration of fetal heart activity, n = 7; and normal singleton pregnancies, n = 52. The levels of all substances measured were significantly reduced in women with anembryonic compared to those with singleton pregnancies which proceeded to term. The serum levels of SP-1, weeks 6-8 (P < 0.01); HCG, weeks 6-8 (P < 0.05); oestradiol, weeks 5-8 (P < 0.05) and progesterone, weeks 6-8 (P < 0.05), were lower in anembryonic pregnancies than in those of pregnancies which spontaneously aborted. These differences may be a reflection of the fact that miscarriage, after the demonstration of fetal heart activity, represents fetal demise at a later stage in pregnancy. In anembryonic pregnancies, significant associations were found between HCG and both oestradiol and progesterone levels from weeks 6 and 8, suggesting that in the absence of an embryo, HCG is the prime determinant of steroid synthesis by the corpus luteum.

Human endometrial peptides: a review of their potential role in implantation and placentation

This paper reviews human endometrial peptide synthesis and discusses the biological function of these peptides in relation to implantation and placentation. Despite the substantial literature on quantitative and qualitative peptide synthesis by the endometrium, it has not been possible to define the function of most of these substances. Various aspects of endometrial morphology, especially the endometrial leukocytes, are discussed in an attempt to relate cellular structure and function. A number of serum proteins are produced by the endometrial glandular epithelium and may play a role in early embryo development. Extracellular matrix proteins produced by stromal cells are important for endometrial structure and integrity but also provide a site for trophoblast attachment. Several hormones and binding proteins are also produced by stromal cells and probably influence endometrial metabolism. Complement factors and secretory component may have a role in maintaining a sterile intrauterine environment. Many other endometrial proteins have been less well characterized and their role in endometrial physiology at present remains uncertain. Perhaps the most exciting advance has been the realization that a number of peptide regulatory factors (cytokines and growth factors) are not only produced by the endometrium but play an integral part in the mediation of oestrogen-induced growth and differentiation of the endometrium and with the local metabolic and physiological processes.

Change in obstetric practice in response to fear of litigation in the British Isles

The increased number of medical negligence claims against obstetricians and gynaecologists has led to concerns about a trend towards defensive medical practice in the UK. The attitudes of obstetricians in the British Isles to tests of fetal and maternal wellbeing, which may influence decisions about patient care, were investigated in 3194 Fellows and Members of the Royal College of Obstetricians and Gynaecologists. Perceived accuracy of tests ranged from 86.3% for fetal blood sampling to 25.9% for biochemical tests. Despite some tests being perceived as having poor accuracy, all were widely used even by those who deemed them inaccurate. The most frequent explanations given for this paradoxical finding were that such tests were an aid to clinical judgement and were necessary for medicolegal reasons. Our data indicate that tests deemed to be inaccurate are used in clinical practice because some obstetricians fear litigation. Our findings were not influenced by age, gender, grade of doctor, or site of practice.

Patterns of maternal weight gain in pregnancy

A retrospective study of 1145 pregnant women showed that trends in mean maternal weight gain from the time of booking until delivery were not linear. Statistically significant lower rates of maternal weight gain were seen before 16 weeks, after 36 weeks and between 28 and 32 weeks gestation (P less than 0.05). The mean maternal weight gain was 10.71 kg (SD 4.3) and the mean weekly weight gain was 0.38 kg (SD 0.16). A wide variation of maternal weight gain was seen in women with a normal outcome. The mean weight gain in heavy (greater than 68 kg) and light (less than 55.4 kg) women was less than that in women whose weight was in the third quartile (60-68 kg, P less than 0.05). The mean maternal weight gain was less in young (less than 20 years) women than in older women (greater than 25 years; P less than 0.05), less in parous than in primigravid women from week 37 onwards (P less than 0.05), less in smokers than in non-smokers from 20 weeks onwards (P less than 0.05), and greater in hypertensive women (BP less than 140/90) than in normotensive women (P less than 0.05) from week 24 onwards. The mean weight gain in women who had small for gestational age (SGA) infants was not significantly different from that in women who had infants that were of appropriate size for gestational age. After taking into account infant and placental weight using multiple regression analysis, the factors that were associated with statistically significant differences in average weekly weight gain were parity, body mass index, smoking habit and raised blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Repeated measurement of maternal weight during pregnancy. Is this a useful practice?

A retrospective study of 1092 pregnant women showed that the use of a centile chart of maternal weight gain was not effective at detecting women who give birth to small for gestational age (SGA) infants. Multiple regression analysis showed that of the various weight measurements recorded, weekly weight gain and maternal size at booking were the only factors which had a significant association with infant birthweight after taking into account maternal gestation, age, smoking habit and parity. Low maternal booking weight (less than 51 kg) was the most effective maternal weight measurement for antenatal detection of SGA infants (positive predictive value 20.0%). Low average weekly maternal weight gain (less than 0.20 kg) had a positive predictive value of only 12.9% for detecting these pregnancies. Weight loss or failure to gain weight over a 2-week interval occurring in the third trimester was observed in 46% of all women studied. Maternal smoking had a positive predictive value of 16.3% in antenatal detection of SGA infants. Maternal weight need be recorded only at booking, with the exception of patients in whom nutrition is of concern. The subsequent routine weighing of patients may produce unnecessary anxiety and should cease.

A risk of malignancy index incorporating CA 125, ultrasound and menopausal status for the accurate preoperative diagnosis of ovarian cancer

Age, ultrasound score, menopausal status, a clinical impression score and serum CA 125 level were assessed to see how they could best distinguish between patients with benign (n = 101) and malignant (n = 42) pelvic masses. Each criteria used alone provided statistically significant discrimination. The most useful individual criteria were a serum CA 125 level of 30 U/ml (sensitivity 81%, specificity 75%) and an ultrasound score of 2 (sensitivity 71%, specificity 83%). Three criteria could be combined in a risk of malignancy index (RMI) which is simply calculated using the product of the serum CA 125 level (U/ml), the ultrasound scan result (expressed as a score of 0, 1 or 3) and the menopausal status (1 if premenopausal and 3 if postmenopausal). This index was statistically virtually as effective a discriminant between cancer and benign lesions as more formal methods. Using an RMI cut-off level of 200, the sensitivity was 85% and the specificity was 97%. Patients with an RMI score of greater than 200 had, on average, 42 times the background risk of cancer and those with a lower value 0.15 times the background risk.

A risk of malignancy index incorporating CA 125, ultrasound and menopausal status for the accurate preoperative diagnosis of ovarian cancer

Age, ultrasound score, menopausal status, a clinical impression score and serum CA 125 level were assessed to see how they could best distinguish between patients with benign (n = 101) and malignant (n = 42) pelvic masses. Each criteria used alone provided statistically significant discrimination. The most useful individual criteria were a serum CA 125 level of 30 U/ml (sensitivity 81%, specificity 75%) and an ultrasound score of 2 (sensitivity 71%, specificity 83%). Three criteria could be combined in a risk of malignancy index (RMI) which is simply calculated using the product of the serum CA 125 level (U/ml), the ultrasound scan result (expressed as a score of 0, 1 or 3) and the menopausal status (1 if premenopausal and 3 if postmenopausal). This index was statistically virtually as effective a discriminant between cancer and benign lesions as more formal methods. Using an RMI cut-off level of 200, the sensitivity was 85% and the specificity was 97%. Patients with an RMI score of greater than 200 had, on average, 42 times the background risk of cancer and those with a lower value 0.15 times the background risk.

A biochemical test for the direct assessment of endometrial function: measurement of the major secretory endometrial protein PP14 in serum during menstruation in relation to ovulation and luteal function

Circulating PP14 was measured by radioimmunoassay in ovulating (n = 12) and anovulatory (n = 3) women throughout the menstrual cycle, the highest levels of serum PP14 being seen during menstruation and in the late luteal phase in ovulating women. Mean serum PP14 levels on days 1-7 and 24-28 of the menstrual cycle were significantly higher than those observed from days 8 to 23 (P less than 0.0005 and P = 0.005 respectively). There was no difference in mean PP14 levels observed in the menstrual and luteal phase. By contrast, serum PP14 was rarely detected in anovulatory cycles. During the luteal phase, mean serum PP14 levels were apparently not related to serum progesterone levels. However, mean PP14 levels during the menstrual phase were significantly higher in the group of women with the highest progesterone production (Pmax greater than 39 nmol/l) (P less than 0.002) in comparison with levels seen in ovulating women with lower progesterone production (Pmax less than 32 nmol/l). These findings suggest that the synthesis and secretion of PP14 is influenced by ovulation and luteal function. Serum PP14 measurements may provide useful information about the endometrium in relation to fertility, and that these measurements during the menstrual cycle may distinguish between ovulatory and anovulatory cycles.

De novo synthesis of placental protein-14 (PP14) and not PP12 by monolayer cultures of glandular epithelium of gestational endometrium

Nine monolayer cell cultures of glandular epithelium from gestational endometrium were established from six apparently healthy women undergoing elective termination of pregnancy (7-11 weeks gestation). Radiolabel incorporation studies showed increasing incorporation of [35S]methionine into proteins present in supernatant and cytosol fractions over 48 h. The secreted proteins represented approximately 20% of the total incorporation of methionine into cytosolic proteins. De novo synthesis and secretion of placental protein-14 (PP14) and not PP12 was identified by a novel combination of line immunoelectrophoresis and autoradiography. All monolayer cultures demonstrated the presence of radiolabeled PP14, but not PP12, in the culture supernatants. These observations suggest that the glandular epithelial cells are the major site of synthesis and secretion of PP14 in human gestational endometrium.