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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology and the Hospital for Children and Adolescents, Helsinki University Central Hospital; and Department of Clinical Chemistry, University of Helsinki, Helsinki, Finland.
Address reprint requests to: Mikko Loukovaara, MD, Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Haartmaninkatu 2, 00290 Helsinki, Finland; e-mail: mikko.loukovaara{at}hus.fi.
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ABSTRACT |
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METHODS: Cord serum epidermal growth factor concentrations were measured at birth by a sandwich-type time-resolved immunofluorometric assay in 63 pregnancies complicated by insulin-dependent diabetes mellitus, in 25 pregnancies complicated by insulin-treated gestational diabetes, and in 56 normal pregnancies.
RESULTS: Cord serum epidermal growth factor correlated positively with the duration of pregnancy in diabetic and normal pregnancies. In a subgroup of women at similar gestational ages (38–39 weeks), cord serum epidermal growth factor concentrations were higher in pregnancies complicated by insulin-dependent diabetes mellitus (962 ± 211 ng/L, P = .047; n = 9) and in pregnancies complicated by gestational diabetes (1133 ± 115 ng/L, P = .001; n = 9) than in controls (564 ± 75 ng/L; n = 22). In multiple regression analysis, only umbilical artery hemoglobin in diabetic pregnancies and vaginal delivery in normal pregnancies were associated with cord serum epidermal growth factor.
CONCLUSION: Epidermal growth factor concentrations are higher than normal in fetuses of diabetic mothers at term. Pregnancy complications, such as hypertensive disorders, fetal hypoxia and fetal malgrowth, may not explain the rise in epidermal growth factor levels. We hypothesize that the rise in epidermal growth factor levels is a metabolic response of the fetoplacental unit to diabetes-related hyperglycemia.
LEVEL OF EVIDENCE: III
Epidermal growth factor may play an important role in the physiology of human pregnancy. First, epidermal growth factor increases the placental secretion of chorionic gonadotropin.2,3 Second, epidermal growth factor may regulate fetoplacental growth through its mitogenic action. Concordant with this, low maternal urine epidermal growth factor levels in early pregnancy predict the development of intrauterine growth restriction.4 Intra-uterine growth restriction also is associated with suppressed epidermal growth factor levels in amniotic fluid5,6 and cord serum.7 Epidermal growth factor levels in the first urine to be voided are lower than normal both in infants with intrauterine growth restriction and in infants with macrosomia.8
Maternal diabetes frequently is associated with fetoplacental malgrowth, especially macrosomia. Furthermore, as a response to hyperglycemia, diabetes causes increased insulin synthesis in the fetus.9 Thus, based on the proposed role of epidermal growth factor in the regulation of fetal growth4–8 and on the recent finding that epidermal growth factor exerts insulin-like effects,10 it is of interest to study whether maternal diabetes is associated with altered epidermal growth factor levels in the fetus. The purpose of this study was to examine cord serum epidermal growth factor concentrations in pregnancies complicated by insulin-dependent diabetes mellitus, in pregnancies complicated by insulin-treated gestational diabetes, and in normal pregnancies.
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MATERIALS AND METHODS |
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). An attempt was made to enroll all diabetic women during this period. Control women were enrolled prospectively during the same time period as diabetic women. All study subjects gave their informed consent. The study was conducted with the approval of the local institutional review board in accordance with the tenets of the Declaration of Helsinki.
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Twenty-five women had insulin-treated gestational diabetes. Gestational diabetes was diagnosed with a 2-hour oral glucose tolerance test (75 g) after overnight fasting. Abnormal plasma glucose values for fasting, 1-hour, and 2-hour values were at or above 4.8, 10, and 8.7 mmol/L, respectively, which represent the 97.5 percentile values of pregnant Finnish women.11 Women with at least 2 abnormal values on the oral glucose tolerance test were hospitalized for a 24-hour blood glucose profile (7 values). All women were treated by diet (1800–2000 kcal/day). Insulin was added when the preprandial capillary whole blood glucose was at least 5.5 mmol/L repeatedly or 1 preprandial value was at least 5.5 mmol/L and 1 postprandial value at least 7.8 mmol/L in the 24-hour glucose profile. The control population consisted of 56 healthy pregnant women. They were either without any risk factors for gestational diabetes (n = 23) or had a normal oral glucose tolerance test (n = 33).
In diabetic women, hemoglobin A1C (Hb A1C) was assessed every 4–6 weeks by ion-exchange high-performance liquid chromatography (Diamat, Bio-Rad Laboratories, Hercules, CA). The last Hb A1C value during pregnancy was used for statistical analyses. The last measurement was performed at a median of 16 days (range, 0–153) before delivery.
After the delivery of the infant, the umbilical cord was double clamped and venous blood collected. Serum was separated by centrifugation, and samples were stored at -80°C until analyzed. Epidermal growth factor concentrations were measured by a sandwich-type time-resolved immunofluorometric assay.12 The sensitivity of the assay is 2.5 ng/L, and the measuring range is 2.5–5,000 ng/L. The intra- and interassay imprecisions are 5.1% to 6.7% and 6.9% to 8.6%, respectively.
Relative birth weight was expressed as standard deviation (SD) units (z score) using a large Finnish standard population as a reference.13 Newborn infants were considered large-for-gestational age when the relative birth weight exceeded 2 SDs.
Blood pressure was considered increased when the following 2 criteria were met at 2 measuring sessions of at least 24 hours apart: first, the diastolic pressure increased 15 mm Hg or more from the first measurement during pregnancy until the end of pregnancy, and second, the final level reached 90 mm Hg or more. Chronic hypertension and pregnancy-induced hypertension were defined as high blood pressure before 20 weeks and after 20 weeks of gestation, respectively. Preeclampsia was defined as high blood pressure and proteinuria (0.3 g or more/24 hours) after 20 weeks of gestation. According to these criteria, 5 women with insulin-dependent diabetes mellitus had chronic hypertension, 1 had pregnancy-induced hypertension, and 7 had preeclampsia. Of the women with gestational diabetes, 3 had chronic hypertension, 3 had pregnancy-induced hypertension, and 3 had preeclampsia.
The SPSS statistical package (SPSS Inc, Chicago, IL) was used for data analysis. Continuous variables were compared by analysis of variance followed by Dunnett’s multiple comparisons test. Categorical data were compared by the Fisher exact test. Spearman correlation coefficients were calculated to examine bivariate relationships. Multiple regression analyses were performed with the stepwise procedure with P 
.15 as the entry criterion. Based on the previously reported SD of about 30% in cord serum epidermal growth factor concentrations,7 we calculated that 6 subjects per group would be needed for a power of 80% to show a 50% difference between groups at P level of .05. The results are presented as mean ± standard error of the mean unless otherwise stated. P < .05 was considered statistically significant.
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RESULTS |
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The duration of pregnancy was shorter in women with diabetes than in healthy women (Table 1
). However, cord serum epidermal growth factor correlated positively with the duration of pregnancy (Table 2). We therefore compared cord serum epidermal growth factor concentrations in women delivering at similar gestational ages, that is, at 38–39 weeks (266–279 days). In this subgroup, epidermal growth factor values were higher in pregnancies with insulin-dependent diabetes mellitus and in pregnancies with gestational diabetes than in controls (Figure 1).
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. In addition to the positive correlation between cord serum epidermal growth factor and the duration of pregnancy, there was a positive correlation between cord serum epidermal growth factor and umbilical artery hemoglobin both in diabetic and in normal pregnancies. Cord serum epidermal growth factor did not correlate with maternal age, prepregnancy body mass index, Hb A1C, birth weight, birth weight z score, or umbilical artery gas variables.
For multiple regression analysis, cord serum epidermal growth factor was included as the dependent variable, and continuous variables in Table 2 were included as independent variables. Smoking, hypertensive disorders, and delivery mode were included as dichotomous variables. In this model, umbilical artery hemoglobin was significantly associated with epidermal growth factor in diabetic pregnancies (R2 = 0.13, P = .001), and vaginal delivery was significantly associated with epidermal growth factor in normal pregnancies (R2 = 0.18, P = .001). Other variables did not show a significant independent effect.
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DISCUSSION |
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Multiple regression analysis suggested that pregnancy complications, such as hypertensive disorders, fetal hypoxia and fetal malgrowth, may not explain the raised cord serum epidermal growth factor levels in diabetes. Thus, maternal diabetes per se appears to cause the rise in cord serum epidermal growth factor levels. The result is concordant with a study in nonpregnant diabetic subjects in whom diabetes itself and not its complications raise epidermal growth factor levels in blood.16 The mechanism by which the diabetic hormonal environment alters epidermal growth factor levels remains obscure. However, it is interesting to note that epidermal growth factor exerts a full insulin-like effect on human fat cells and that epidermal growth factor requires a much lower concentration than insulin to elicit these effects.10 Based on this, it could be hypothesized that the rise in cord serum epidermal growth factor levels is a metabolic response of the fetoplacental unit to diabetes-related hyperglycemia.
A study by Hofmann et al17 demonstrated similar urinary epidermal growth factor concentrations in women with insulin-treated gestational diabetes and in healthy pregnant women. It is obvious that epidermal growth factor in maternal urine originates from a different source than epidermal growth factor in cord serum because epidermal growth factor does not cross the placenta.18 Thus, together with our data, the finding by Hofmann et al17 suggests that diabetes has different effects on epidermal growth factor metabolism in the mother and in the fetus.
Epidermal growth factor stimulates the synthesis of its own receptor.19,20 It may therefore seem difficult to reconcile our finding of raised epidermal growth factor levels in diabetic pregnancies with the observation that the levels of epidermal growth factor receptors and corresponding mRNA are suppressed in placentas obtained from diabetic women.21 Because good glycemic control appears to restore the amount of maximal binding sites,21 the discrepancy may be explained by the good glycemic control in our subjects, as evidenced by the relatively low Hb A1C levels.
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Footnotes |
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doi: 10.1097/01.AOG.0000110545.64874.49
Received August 22, 2003. Received in revised form November 3, 2003. Accepted November 13, 2003.
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REFERENCES |
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2. Lai WH, Guyda HJ. Characterization and regulation of epidermal growth factor receptors in human placental cell cultures. J Clin Endocrinol Metab 1984;58:344–52.[Abstract]
3. Maruo T, Matsuo H, Oishi T, Hayashi M, Nishino R, Mochizuki M. Induction of differentiation and secretion of human chorionic gonadotropin and placental lactogen in normal human placenta. J Clin Endocrinol Metab 1987; 64:744–50.[Abstract]
4. Lindqvist P, Grennert L, Marsal K. Epidermal growth factor in maternal urine—a predictor of intrauterine growth restriction? Early Hum Dev 1999;56:143–50.[Medline]
5. Varner MW, Dildy GA, Hunter C, Dudley DJ, Clark SL, Mitchell MD. Amniotic fluid epidermal growth factor levels in normal and abnormal pregnancies. J Soc Gynecol Investig 1996;3:17–9.[Medline]
6. Watanabe H. Epidermal growth factor in urine of pregnant women and in amniotic fluid throughout pregnancy. Gynecol Endocrinol 1990;4:43–50.[Medline]
7. Ichiba H, Fujimura M, Takeuchi T. Levels of epidermal growth factor in human cord blood. Biol Neonate 1992; 61:302–7.[Medline]
8. Styne DM. Fetal growth [review]. Clin Perinatol 1998;25: 917–38.[Medline]
9. Schwartz R, Teramo KA. Effect of diabetic pregnancy on the fetus and newborn [review]. Semin Perinatol 2000;24: 120–35.[Medline]
10. Gogg S, Smith U. Epidermal growth factor and transforming growth factor 
mimic the effects of insulin in human fat cells and augment downstream signaling in insulin resistance. J Biol Chem 2002;277:36045–51.
11. Hyvönen K. Gestaatiodiabeteksen esiintyvyys ja seulonta (Incidence and screening of gestational diabetes). Publications of the University of Kuopio, Finland. Original reports 6/1991. Kuopio 1991.
12. Pesonen K, Alfthan H, Stenman U-H, Viinikka L, Perheentupa J. An ultrasensitive time-resolved immunofluorometric assay of human epidermal growth factor. Anal Biochem 1986;157:208–11.[Medline]
13. Pihkala J, Hakala T, Voutilainen P, Raivio K. Uudet suomalaiset sikiön kasvukäyrät (Characteristic of recent fetal growth curves in Finland) [review]. Duodecim 1989; 105:1540–6.[Medline]
14. Scott SM, Buenaflor GG, Orth DN. Immunoreactive human epidermal growth factor concentrations in amniotic fluid, umbilical artery and vein serum, and placenta in full-term and preterm infants. Biol Neonate 1989;56: 246–51.[Medline]
15. Oval J, Hershberg R, Gansbacher B, Gilboa E, Schlessinger J, Taetle R. Expression of functional epidermal growth factor receptors in a human hematopoietic cell line. Cancer Res 1991;51:150–6.
16. Lev-Ran A, Hwang DL. Epidermal growth factor and platelet-derived growth factor in blood in diabetes mellitus. Acta Endocrinol (Copenh) 1990;123:326–30.[Medline]
17. Hofmann GE, Rao CV, Brown MJ, Murray LF, Schultz GS, Siddiqi TA. Epidermal growth factor in urine of nonpregnant women and pregnant women throughout pregnancy and at delivery. J Clin Endocrinol Metab 1988; 66:119–23.[Abstract]
18. Hofmann GE, Abramowicz JS. Epidermal growth factor (EGF) concentrations in amniotic fluid and maternal urine during pregnancy. Acta Obstet Gynecol Scand 1990;69: 217–21.[Medline]
19. Clark AJL, Ishii S, Richert N, Merlino GT, Pastan I. Epidermal growth factor regulates the expression of its own receptor. Proc Natl Acad Sci USA 1985;82:8374–8.
20. Earp HS, Austin KS, Blaisdell J, Rubin RA, Nelson KG, Lee LW, et al. Epidermal growth factor (EGF) stimulates EGF receptor synthesis. J Biol Chem 1986;261:4777–80.
21. Fujita Y, Kurachi H, Morishige K, Amemiya K, Terakawa N, Miyake A, et al. Decrease in epidermal growth factor receptor and its messenger ribonucleic acid levels in intra-uterine growth-retarded and diabetes mellitus-complicated pregnancies. J Clin Endocrinol Metab 1991;72:1340–5.[Abstract]
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P = .004, 
P = .047 (vs controls).