Hum. Reprod. Advance Access originally published online on September 7, 2006
Human Reproduction 2006 21(11):3019-3021; doi:10.1093/humrep/del058
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Correlation between first trimester fetal bone length and maternal serum pregnancy-associated plasma protein-A (PAPP-A)
1 U.O. Ostetricia e Ginecologia, Istituto G. Gaslini, Università di Genova and 2 Laboratorio di Analisi, Istituto G. Gaslini, Genova, Italy
3 To whom correspondence should be addressed at: U.O. Ostetricia e Ginecologia, Istituto G. Gaslini, Largo Gaslini 5, 16147 Genova, Italy. E-mail: fprefumo{at}sgul.ac.uk
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Abstract |
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BACKGROUND: Pregnancy-associated plasma protein-A (PAPP-A) is produced by the embryo and placenta during pregnancy, and its maternal serum concentrations are related to subsequent fetal growth. Evidence from animal models and in vitro experiments suggests that PAPP-A is particularly involved in the regulation of bone development. The aim of this study was to assess the correlation between late first trimester fetal bone length and maternal serum levels of PAPP-A. METHODS: In a cross-sectional observational study, ultrasound measurements of fetal long bones and fluorimetric immunoassays for maternal serum PAPP-A were performed in 514 singleton pregnancies at 10–14 weeks of gestation. RESULTS: There were 501 uncomplicated pregnancies. There were significant correlations between PAPP-A values and length of humerus, femur and tibia [r values 0.12 (P = 0.01), 0.11 (P = 0.01) and 0.10 (P = 0.03), respectively]. The association with the length of ulna and foot did not reach statistical significance (r values 0.08 and –0.03, respectively). CONCLUSIONS: Maternal serum PAPP-A levels at 10–14 weeks of gestation are significantly associated with the length of fetal long bones such as humerus, femur and tibia. This provides further evidence that PAPP-A may be involved in the regulation of bone development.
Key words: bone growth/bone length/fetus/PAPP-A
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Introduction |
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Insulin-like growth factors (IGF) 1 and 2 are important regulatory factors in fetal growth and post-natal development (Stewart and Rotwein, 1996
). IGF activity is modulated by a family of six IGF-binding proteins (IGFBPs) (Firth and Baxter, 2002). Of these, IGFBP-4 appears to be the one functioning most like a traditional binding protein (Mazerbourg et al., 2004) and may serve as a pericellular reservoir for IGFs (Mohan et al., 1989). Pregnancy-associated plasma protein-A (PAPP-A) was identified as a zinc-binding metalloproteinase secreted by normal human fibroblasts with IGFBP-4 as its substrate (Sinosich et al., 1983; Lawrence et al., 1999). Cleavage of IGFBP-4 by PAPP-A results in increased bioavailability and mitogenic effectiveness of IGFs in vitro (Conover et al., 1995; Byun et al., 2001; Ortiz et al., 2003).
PAPP-A is produced in great amounts during pregnancy by the syncytiotrophoblast (Guibourdenche et al., 2003) and can be detected in placental tissue, decidua, maternal serum, amniotic and coelomic fluids (Grudzinskas et al., 1985; Iles et al., 1994). In the mouse, PAPP-A was also shown to be expressed by a number of tissues at all embryonic stages investigated (Conover et al., 2004a). In the same animal model, individuals homozygous for targeted disruption of the PAPP-A gene were viable but 60% the size of wild-type littermates at birth (Conover et al., 2004a). This growth regulatory activity may explain the association between reduced maternal serum PAPP-A levels and fetal growth disturbance observed in human pregnancies (Smith et al., 2002; Dugoff et al., 2004; Krantz et al., 2004).
As recent evidence suggested that IGFBP-4 and PAPP-A may be involved in skeletal growth and remodelling (Miyakoshi et al., 2001; Ortiz et al., 2003; Conover et al., 2004b), we sought to investigate the relationship between maternal serum levels of PAPP-A and fetal bone length in the late first trimester of pregnancy.
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Patients
In this cross-sectional study, measurements of the fetal long bones and maternal serum PAPP-A were performed on consecutive fetuses enrolled in the setting of a screening programme for chromosomal abnormalities based on first trimester combined test (nuchal translucency, maternal serum PAPP-A and free-
-HCG) (De Biasio et al., 1999). Only singleton pregnancies were included. Women with a known medical condition (e.g. diabetes mellitus, connective tissue disease, chronic hypertension) or a history of recurrent miscarriage were excluded. Gestational age was calculated from the last menstrual period, confirmed by crown–rump length measurement (CRL). Local ethical committee approval was obtained for this study, and all women gave their informed consent.
Ultrasound examination
Ultrasound examinations were performed transabdominally with an ATL HDI 5000 ultrasound device (Advanced Technology Laboratories, Bothell, WA, USA) equipped with a 5 MHz curvilinear probe. In each fetus, a midline sagittal view was obtained, and CRL was measured. A single measurement of the length of humerus, ulna, femur, tibia and foot was then attempted from the longest section of each structure, with the fetal image magnified so as to occupy three quarters of the screen as previously described (De Biasio et al., 2002). All examinations were performed by a single investigator experienced in first trimester sonography. The coefficient of variation (CV) ranged from 7.9% for ulnar length to 10.0% for femur and tibia length (De Biasio et al., 2002). In all cases, a careful search for fetal abnormalities was performed. Each fetus was examined only once for the purpose of the study.
PAPP-A measurement
Five millilitres of maternal blood was obtained by venipuncture at the time of the ultrasound scan, allowed to clot into a non-heparinized tube and centrifuged. PAPP-A was assayed on maternal serum by a fluorimetric immunoassay (Kryptor, Brahms, Hennigsdorf, Germany). The assay detection limit was <0.04 IU/l. The inter-assay CV was 5.4%. Absolute concentrations of the analyte were converted into multiples of the median (MoM) corrected for CRL and maternal weight. All marker reference medians were previously determined in the local population (De Biasio et al., 1999).
Statistical analysis
The MoM of PAPP-A were log-transformed. Logarithmic transformation of the data allowed the use of parametric tests because the marker measurements seemed to fit a Gaussian distribution. In order to correct for the normal variation of fetal bone length with CRL, this was expressed as bone length Z scores. Z scores were calculated as the [(actual length – mean length for CRL)/standard deviation for CRL]. Z scores were derived from previously published reference values (De Biasio et al., 2002). The correlation between PAPP-A and bone length was assessed by Pearson’s correlation coefficients. All calculations were performed using the SPSS software package (release 11.5, SPSS Inc., Chicago, IL, USA). P values <0.05 were considered statistically significant. We calculated that in order to detect a correlation coefficient (r) of 0.15 at a level of significance 
= 0.05 and with a power of 90%, a sample size of 400 pregnancies would be required (Bland, 2000).
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Results |
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A total of 514 singleton pregnancies were enrolled into the study. Fetuses with abnormal karyotype (n = 1) or major structural abnormalities (n = 2) were excluded from the study, as well as cases of pregnancy loss (n = 10). In the remaining 501 uncomplicated pregnancies, the mean maternal age was 31.2 years (range 19.6–41.1 years). The mean gestational age at scan was 12.0 weeks (range 10.0–13.9 weeks). Ethnic origin was Caucasian in 99.0% of cases, 67.5% of the women were nulliparous, 8.2% of them were smokers. An ultrasound measurement was obtained in the 96.0% (482/501) of cases for the humerus, 96.0% (483/501) for ulna, 96.0% (481/501) for femur, 96.0% (482/501) for tibia and 93.8% (470/501) of cases for foot. Table I shows the correlation coefficients between log-transformed MoM of maternal serum PAPP-A and fetal limb measurement Z scores. A statistically significant correlation was found between PAPP-A and humerus, femur and tibia length.
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Discussion |
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In this study, we demonstrate that measurements of fetal bone length at 10–14 weeks of gestation are significantly associated with maternal serum levels of PAPP-A. The correlation coefficient between log-transformed PAPP-A MOM and length Z score was 0.12, 0.11 and 0.10, respectively, for humerus, femur and tibia. The correlation with ulnar length approached but did not reach statistical significance (r = 0.08, P = 0.08). Measurements of a composite limb segment, foot length, did not appear to be related to maternal serum PAPP-A. This is not surprising as the direct effect of long bone length is likely to have a reduced impact on the overall length of the foot, as often observed in extreme cases such as congenital skeletal dysplasia (Pilu and Nicolaides, 1999
).
During pregnancy, PAPP-A is detectable in placental tissue, decidua, maternal serum, amniotic and coelomic fluids, and in a number of tissues at different embryonic stages (Grudzinskas et al., 1985; Iles et al., 1994; Guibourdenche et al., 2003; Conover et al., 2004a). Conover et al. (2004a) demonstrated the presence of PAPP-A transcripts in wild-type mice at all embryonic stages between E8.5 and E13.5. Moreover, mice homozygous for targeted disruption of the PAPP-A gene were viable but 60% the size of wild-type littermates at birth. The impact of the mutation was exerted during the early embryonic period prior to organogenesis, resulting in proportional dwarfism (Conover et al., 2004a). A general delay in bone mineralization was also observed. These findings support the view that PAPP-A, through its capacity to modulate the bioavailability of IGF, is central in the regulation of bone remodelling (Miyakoshi et al., 2001; Ortiz et al., 2003; Conover et al., 2004b).
Another important site of PAPP-A expression is the placenta. In particular, the differentiating syncytiotrophoblast seems to be its most important source (Guibourdenche et al., 2003). Abnormalities in placental development are likely to affect the amount of PAPP-A released by syncytiotrophoblast into the maternal circulation, and therefore explain the association between reduced maternal serum PAPP-A levels and fetal growth disturbance observed in human pregnancies (Smith et al., 2002; Dugoff et al., 2004; Krantz et al., 2004).
However, the dynamics of PAPP-A transport between the fetus, the placenta and the mother are not well studied. Despite the fact that PAPP-A is detectable in embryonic and fetal tissues as well as in amniotic and coelomic fluids (Grudzinskas et al., 1985; Iles et al., 1994; Conover et al., 2004a), its presence in the fetal blood is reported in only one study (Grudzinskas et al., 1985). Therefore, it is equally possible that PAPP-A produced in the placenta may be partly transferred to the fetal circulation, as well as PAPP-A of fetal origin being transferred to the maternal circulation.
Our finding of a correlation between fetal bone length in the first trimester and maternal serum levels of PAPP-A supports the existence of some relationship between the maternal and fetal compartments. This is reinforced by the findings of Leung and colleagues, who recently found a significant correlation between fetal maxillary length and maternal serum PAPP-A at a similar gestational age (Leung et al., 2006). It can be argued that fetal bone length may just be a result of overall fetal growth, and therefore the correlation between bone length and PAPP-A may just reflect that between fetal size and PAPP-A. However, both PAPP-A and fetal bone length measurements used in our analysis were corrected for CRL, which is the most widely employed indicator of fetal growth at this gestational age. Therefore, the correlation observed seems to be specific and independent of overall fetal size.
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Acknowledgements |
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Dr Prefumo was supported by a Marie Curie Reintegration Fellowship of the European Community under contract number MERG-CT-2004-006365.
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References |
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Bland JM. (2000) An Introduction to Medical Statistics(Oxford University Press, Oxford.).
Byun D, Mohan S, Yoo M, Sexton C, Baylink DJ, Qin X. (2001) Pregnancy-associated plasma protein-A accounts for the insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4) proteolytic activity in human pregnancy serum and enhances the mitogenic activity of IGF by degrading IGFBP-4 in vitro. J Clin Endocrinol Metab 86:847–854.
Conover CA, Durham SK, Zapf J, Masiarz FR, Kiefer MC. (1995) Cleavage analysis of insulin-like growth factor (IGF)-dependent IGF-binding protein-4 proteolysis and expression of protease-resistant IGF-binding protein-4 mutants. J Biol Chem 270:4395–4400.
Conover CA, Bale LK, Overgaard MT, Johnstone EW, Laursen UH, Fuchtbauer EM, Oxvig C, van Deursen J. (2004a) Metalloproteinase pregnancy-associated plasma protein A is a critical growth regulatory factor during fetal development. Development 131:1187–1194.
Conover CA, Chen BK, Resch ZT. (2004b) Regulation of pregnancy-associated plasma protein-A expression in cultured human osteoblasts. Bone 34:297–302.[Medline]
De Biasio P, Siccardi M, Volpe G, Famularo L, Santi F, Canini S. (1999) First-trimester screening for Down syndrome using nuchal translucency measurement with free beta-hCG and PAPP-A between 10 and 13 weeks of pregnancy—the combined test. Prenat Diagn 19:360–363.[CrossRef][Web of Science][Medline]
De Biasio P, Prefumo F, Lantieri PB, Venturini PL. (2002) Reference values for fetal limb biometry at 10–14 weeks of gestation. Ultrasound Obstet Gynecol 19:588–591.[CrossRef][Web of Science][Medline]
Dugoff L, Hobbins JC, Malone FD, Porter TF, Luthy D, Comstock CH, Hankins G, Berkowitz RL, Merkatz I, Craigo SD, et al. (2004) First-trimester maternal serum PAPP-A and free-beta subunit human chorionic gonadotropin concentrations and nuchal translucency are associated with obstetric complications: a population-based screening study (The FASTER Trial). Am J Obstet Gynecol 191:1446–1451.[CrossRef][Web of Science][Medline]
Firth SM and Baxter RC. (2002) Cellular actions of the insulin-like growth factor binding proteins. Endocr Rev 23:824–854.
Grudzinskas JG, Obiekwe BC, Perry LA, Houghton DJ, Sinosich MJ, Bolton AE, Chard T. (1985) The relation of pregnancy associated plasma protein A (PAPP-A) in the umbilical circulation of the human fetus to oestriol production by the placenta. Asia Oceania J Obstet Gynaecol 11:425–428.[Medline]
Guibourdenche J, Frendo JL, Pidoux G, Bertin G, Luton D, Muller F, Porquet D, Evain-Brion D. (2003) Expression of pregnancy-associated plasma protein-A (PAPP-A) during human villous trophoblast differentiation in vitro. Placenta 24:532–539.[CrossRef][Web of Science][Medline]
Iles RK, Wathen NC, Sharma KB, Campbell J, Grudzinskas JG, Chard T. (1994) Pregnancy-associated plasma protein A levels in maternal serum, extraembryonic coelomic and amniotic fluids in the first trimester. Placenta 15:693–699.[Web of Science][Medline]
Krantz D, Goetzl L, Simpson JL, Thom E, Zachary J, Hallahan TW, Silver R, Pergament E, Platt LD, Filkins K, et al. (2004) Association of extreme first-trimester free human chorionic gonadotropin-beta, pregnancy-associated plasma protein A, and nuchal translucency with intrauterine growth restriction and other adverse pregnancy outcomes. Am J Obstet Gynecol 191:1452–1458.[CrossRef][Web of Science][Medline]
Lawrence JB, Oxvig C, Overgaard MT, Sottrup-Jensen L, Gleich GJ, Hays LG, Yates JR, Conover CA 3rd. (1999) The insulin-like growth factor (IGF)-dependent IGF binding protein-4 protease secreted by human fibroblasts is pregnancy-associated plasma protein-A. Proc Natl Acad Sci USA 96:3149–3153.
Leung TY, Chan LW, Leung TN, Fung TY, Sahota DS, Lau TK. (2006) First-trimester maternal serum level of pregnancy-associated plasma protein-A is an independent predictor of fetal maxillary bone length. Ultrasound Obstet Gynecol 27:9–12.[CrossRef][Web of Science][Medline]
Mazerbourg S, Callebaut I, Zapf J, Mohan S, Overgaard M, Monget P. (2004) Up date on IGFBP-4: regulation of IGFBP-4 levels and functions, in vitro and in vivo. Growth Horm IGF Res 14:71–84.[CrossRef][Web of Science][Medline]
Miyakoshi N, Qin X, Kasukawa Y, Richman C, Srivastava AK, Baylink DJ, Mohan S. (2001) Systemic administration of insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4) increases bone formation parameters in mice by increasing IGF bioavailability via an IGFBP-4 protease-dependent mechanism. Endocrinology 142:2641–2648.
Mohan S, Bautista CM, Wergedal J, Baylink DJ. (1989) Isolation of an inhibitory insulin-like growth factor (IGF) binding protein from bone cell-conditioned medium: a potential local regulator of IGF action. Proc Natl Acad Sci USA 86:8338–8342.
Ortiz CO, Chen BK, Bale LK, Overgaard MT, Oxvig C, Conover CA. (2003) Transforming growth factor-beta regulation of the insulin-like growth factor binding protein-4 protease system in cultured human osteoblasts. J Bone Miner Res 18:1066–1072.[CrossRef][Web of Science][Medline]
Pilu G and Nicolaides KH. (1999) Diagnosis of Fetal Abnormalities. The 18–23 Week Scan(Parthenon, Carnforth.).
Sinosich MJ, Davey MW, Teisner B, Grudzinskas JG. (1983) Comparative studies of pregnancy associated plasma protein-A and alpha 2-macroglobulin using metal chelate chromatography. Biochem Int 7:33–42.[Web of Science][Medline]
Smith GC, Stenhouse EJ, Crossley JA, Aitken DA, Cameron AD, Connor JM. (2002) Early-pregnancy origins of low birth weight. Nature 417:916.[CrossRef][Medline]
Stewart CE and Rotwein P. (1996) Growth, differentiation, and survival: multiple physiological functions for insulin-like growth factors. Physiol Rev 76:1005–1026.
Submitted on December 21, 2005; resubmitted on February 2, 2006; accepted on February 7, 2006.
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