Objective: The aim of the present study was to evaluate the effects of fetal gender on serum human chorionic gonadotropin (hCG) and testosterone in normotensive and preeclamptic pregnancies.

Methods: The study consisted of 137 women with singleton pregnancies in the third trimester. Seventy-three pregnancies were uncomplicated; among those were 35 male and 38 female fetuses. Sixty-four pregnancies were complicated by preeclampsia; among those were 33 male and 31 female fetuses. Human chorionic gonadotropin and total testosterone were measured in maternal peripheral blood.

Results: In male-bearing pregnancies, maternal hCG and testosterone serum levels were significantly higher in preeclamptic than normotensive mothers (P < .001). In female-bearing pregnancies, testosterone levels were significantly higher in preeclamptic than normotensive mothers (P < .001), whereas the hCG levels were not significantly different. Male-bearing preeclamptic women had significantly higher testosterone levels than female-bearing preeclamptic women (P < .02), whereas the hCG levels were not significantly different. In uncomplicated pregnancies the hCG levels were significantly higher in female-bearing than in male-bearing mothers (P < .005), whereas the testosterone levels were not significantly different.

Conclusion: In preeclamptic pregnancies with male fetuses, the maternal serum hCG levels were significantly higher than in uncomplicated pregnancies. Total testosterone levels were significantly higher in pregnancies with either gender and significantly higher in male-bearing than in female-bearing pregnancies. This may indicate an androgen influence on the pathophysiologic mechanism of preeclampsia.

^aDepartment of Obstetrics and Gynecology, Haukeland University Hospital, University of Bergen, Bergen, Norway
^bDepartment of Biochemical Endocrinology, Haukeland University Hospital, University of Bergen, Bergen, Norway

(Obstet Gynecol 2002:100:552-556. © 2002 by The American College of Obstetricians and Gynecologists.)

Human chorionic gonadotropin (hCG) is produced in the placental syncytiotrophoblast. The bulk of the hormone is secreted into the maternal circulation. During normal pregnancy the hCG levels increase rapidly until a peak is reached at 60-80 days' gestation. Thereafter, the levels decrease, reaching a nadir at 16-18 weeks' gestation. ^1,2

During the first and second trimesters of normal pregnancy, there are no gender differences in maternal hCG levels. However, from the second to the third trimesters there is a marked shift in maternal hCG serum concentrations. The hCG levels in female-bearing pregnancies increase significantly, whereas they decrease in male-bearing pregnancies. ^3-5

During pregnancy the maternal serum levels of total testosterone increase progressively, whereas the concentration of free testosterone changes little until the third trimester, when it increases two-fold. ^6,7

Elevated hCG levels are found in maternal serum in pregnancies complicated by preeclampsia, and significantly higher testosterone levels are found in preeclamptic than in normotensive pregnancies. ^8,9 The aim of the present study was to evaluate the effects of fetal sex on hCG and testosterone in preeclampsia compared with uncomplicated pregnancies.

Material and Methods

The study consisted of 137 women with singleton pregnancies admitted to our department for antenatal care. Seventy-three of them had uncomplicated pregnancies, and 64 had pregnancies complicated by mild to moderate preeclampsia. In the group of uncomplicated pregnancies 35 were bearing male fetuses and 38 female fetuses. In the group of women with preeclampsia, 33 had male and 31 had female fetuses.

Pregnancies with maternal diabetes, fetal malformations, or chromosomal abnormalities were excluded. Gestational age was calculated from the first day of the last menstrual period, unless ultrasonography results found a discrepancy of 14 days or more.

By the visit when the pregnant women entered the study, they were examined physically. Blood pressure and urine specimens were collected, and detailed ultrasonographic structural examinations of the fetuses were performed. Simultaneously, blood samples were drawn from an antecubital maternal vein for examination of hCG and total testosterone. Hematocrit was analyzed in an ADVIA 120 autoanalyzer (Bayer System, Bayer-Leverkusen, Germany).

Consistent with the definition of the ACOG, preeclampsia was defined as new-onset hypertension after 20 weeks' gestation, with a diastolic blood pressure of 90 mm Hg or higher with concurrent proteinuria of 300 mg/24 hours or greater. Semiquantitative dipstick tests were used for measurement of proteinuria (1+ and 2+ corresponded to 300 mg/24 hours and 500mg/24 hours, respectively). ¹⁰

Human chorionic gonadotropin was measured with a commercial immunometric assay kit (ImmuliteHCG; Diagnostic Products Corporation, Los Angeles, CA). The Third International Standard for hCG was used as a reference standard. The assay has a detection limit of 3 IU/L. The intraassay coefficient of variation was 3.3 and 7.0 for mean hCG levels at 21 and 1500 IU/L, respectively. The interassay coefficient of variation was 7.2 and 9.1 for hCG levels at 21 and 1500 IU/L, respectively.

Testosterone level was determined by a commercially available test from Orion Diagnostica (Espoo, Finland). The test is based on a radioimmunoassay technique. The expected serum testosterone levels ranged between 0.3 and 2.8 nmol/L. The sensitivity was 0.1 nmol/L. The intraassay coefficient of variation was 7.5 and 5.5 for testosterone levels at 1.6 and 26.5 nmol/L, respectively. The interassay coefficient of variation was 7.0 and 4.8 for testosterone levels at 1.2 and 23.3 nmol/L, respectively.

Statistical analyses were carried out by Mann-Whitney test for group differences. A P value less than .05 was considered statistically significant. For correlations, Pearson and Spearman rank correlation tests were used. The study was approved by the Regional Committee for Biomedical Research in West Norway. All participants gave written consent.

Results

The age of the pregnant women ranged between 19 and 42 years, and the gestational age ranged between 30 and 38 weeks.

In the group of preeclamptic women, the diastolic blood pressure ranged from 90 to 110 mm Hg, and no differences were seen between male- and female-bearing pregnancies. Proteinuria was measured to 1+ and 2+, and no difference was found between pregnancies with male and female fetuses.

In the preeclamptic pregnancies the hematocrit values were within the normal range (0.35-0.44). No difference was seen between male- and female-bearing pregnancies. None of the fetuses were growth restricted, and no weight differences between the sexes were found after delivery. Relevant clinical data are shown in Table 1.

In uncomplicated pregnancies with female fetuses, the maternal serum hCG levels were significantly higher than in those with male fetuses (P < .005), whereas no significant gender differences were found in the maternal serum testosterone values. In preeclamptic pregnancies with male fetuses, the maternal serum hCG levels were significantly higher than in the normotensive male group (P < .001). This difference was not found between preeclamptic and uncomplicated pregnancies with female fetuses.

The maternal serum levels of total testosterone were significantly higher in preeclamptic than in normotensive pregnancies with male as well as with female fetuses (P < .001). Male-bearing preeclamptic pregnancies had significantly higher maternal serum testosterone levels than female-bearing pregnancies complicated by preeclampsia (P < .02).

No statistical correlations were found between hCG and total testosterone in maternal blood either in male- or female-bearing pregnancies. Data for the hCG and testosterone values are given in Tables 2 and 3,respectively.

Discussion

The present study confirmed the previously reported findings of significantly higher hCG levels in maternal serum in third-trimester uncomplicated female-bearing pregnancies than in uncomplicated male-bearing pregnancies. ^3-5 Several studies have found elevated hCG concentrations in maternal blood in preeclamptic pregnancies but without regard to fetal gender. ^8,10-14 In the present study the hCG levels in maternal blood in male-bearing preeclamptic pregnancies were significantly higher compared with male-bearing uncomplicated pregnancies, whereas in preeclampsia with female fetuses no significant increase in the maternal hCG level was observed.

The placenta seems to play a fundamental role in preeclampsia, as the condition improves rapidly after its removal. Examinations of the placenta in pregnancies complicated by preeclampsia have revealed focal cellular necrosis with increased mitotic activity in the syncytiotrophoblast and cellular proliferation in the cytotrophoblast. A transformation of the cytotrophoblast into the syncytiotrophoblast also has been reported. ^15,16 These changes might explain the elevated maternal serum hCG levels in male-bearing preeclamptic pregnancies, but there is still no explanation for no increase in maternal serum hCG levels in female-bearing pregnancies with preeclampsia.

The serum levels of total testosterone increase throughout normal pregnancy and are primarily a result of progressive estrogen-induced increase in the concentration in sex hormone-binding globulin concentrations. ^6,7 In preeclamptic pregnancies, however, studies have found lower maternal serum levels of estrogen than in normal pregnancies, so it is likely that other mechanisms mediate the maternal serum testosterone levels. ¹⁷

The sources for the increased testosterone levels in maternal serum are not known but could be the ovarian theca-interstitial cells and the maternal adrenal cortex, which might be stimulated by hCG throughout pregnancy. The fetal serum levels of testosterone are much lower than the maternal levels. Because of the stimulating effect of hCG on the fetal testis, the testosterone levels in male fetuses are significantly higher than in female fetuses. The fetal ovaries are regarded as hormonally inactive in the first part of pregnancy, but later they might have steroidogenic capacity. ^18-21

In the present study no correlations were found between maternal serum levels of hCG and total testosterone. In uncomplicated pregnancies no significant gender differences were found. The significantly increased maternal serum testosterone levels in preeclamptic pregnancies with male fetuses as well as with female fetuses, and the significantly higher total testosterone maternal serum levels in male- than in female-bearing preeclamptic pregnancies, were not related to maternal hCG levels only.

It has been postulated that preeclampsia could result from a mutation in a paternally imprinted, maternally active gene. It is also known that only the paternal allele is expressed in human placenta. ^22,23 A paternal immunogenetic factor has been suggested, because significantly more preeclampsia is found in pregnancies with changed paternity. ²⁴

Preeclampsia is a complex disease of unknown origin. A placental involvement in the pathophysiologic mechanism of the disease is likely, and our observations could indicate an androgenic-mediated effect on preeclampsia.

References

1. Bagshave KD, Searle E, Wass MB. Human gonadotropin. In: Gray CH, James VTH, eds. Hormones in blood. 3rd ed. Vol 1. London: Academic Press, 1979:363-408.

2. Braunstein GD, Rasor J, Adler R, Danzer H, Wade ME. Serum human chorionic gonadotropin levels throughout normal pregnancy. Am J Obstet Gynecol 1976;126:678-81.

3. Danzer H, Braunstein GD, Rasor J, Forsythe AW. Maternal serum chorionic gonadotropin concentrations and fetal sex prediction. Fertil Steril 1984;34:336-40.

4. Steier JA, Myking OL, Ulstein M. Human chorionic gonadotropin in cord blood and peripheral maternal blood in singleton and twin pregnancies at delivery. Acta Obstet Gynecol Scand 1989;68:689-92.

5. Steier JA, Myking OL, Bergsjø PB. Correlation between fetal sex and human chorionic gonadotropin in peripheral maternal blood and amniotic fluid in second and third trimester normal pregnancies. Acta Obstet Gynecol Scand 1999;78:363-71.

6. Bammann BL, Coulam CB, Yang NS. Total and free testosterone during pregnancy. Am J Obstet Gynecol 1980;137:293-8.

7. Rivarola MA, Forest MG, Migeon CJ. Testosterone, androstendione and dehydroepiandrosterone in plasma during pregnancy and delivery: Concentration and protein binding. J Clin Endocrinol Metab 1968;28:34-40.

8. Sorensen TK, Williams MA, Zingheim RW, Clement SJ, Hickok DE. Elevated second-trimester human chorionic gonadotropin and subsequent pregnancy-induced hypertension. Am J Obstet Gynecol 1993;169:834-8.

9. Acromite MT, Mantzoros CS, Leach RE, Hurwitz J, Doney LG. Androgens in preeclampsia. Am J Obstet Gynecol 1999;180:60-3.

10. Levine RJ, Ewell MG, Hauth JC, Curet LB, Catalano PM, Morris CD, et al. Should the definition of preeclampsia include a rise in diastolic blood pressure of 15 mm Hg to a level of <90 mm Hg in association with proteinuria? Am J Obstet Gynecol 2000;183:787-92.

11. Said ME, Campbell DM, Azzam ME, MacGilligan I. Beta human chorionic gonadotropin levels before and after the development of preeclampsia. Br J Obstet Gynecol 1984;91:772-6.

12. Witlin AG, Saade GR, Mattar F, Sibai BM. Predictors of neonatal outcome in women with severe preeclampsia or eclampsia between 24 and 33 weeks of gestation. Am J Obstet Gynecol 2000;82:607-11.

13. Feinberg RF, Kliman HJ, Cohen AW. Preeclampsia, trisomy 13, and the placental bed. Obstet Gynecol 1991;78:505-8.

14. Rijhsinghani A, Yankowitz J, Strauss RA, Kuller JA, Patil S, Williamson RA. Risk of preeclampsia in second-trimester triploid pregnancies. Obstet Gynecol 1997;90:884-8.

15. Jones CJP, Fox H. An ultrastructural and ultrahistochemical study of the human placenta in maternal pre-eclampsia. Placenta 1980;1:61-76.

16. Hoshina M, Ashitaka Y, Tojo S. Immunohistochemical interaction on antisera to hCG and its subunits with chorionic tissue of early gestation. Endocrinol Jpn 1979;26:175-84.

17. MacGillivray I. Pre-eclampsia. The hypertensive disorder of pregnancy. London: W.B. Saunders Company Ltd, 1983:56-163.

18. Huhtaniemi IT, Korenbrot CC, Jaffe RB. hCG binding and stimulation of testosterone biosynthesis in human fetal testis. J Clin Endocrinol Metab 1977;44:963-7.

19. Jaffe RB, Serón-Ferré M, Huhtaniemi I, Korenbrot C. Regulation of the primate fetal adrenal gland and testis in vitro and in vivo. J Steroid Biochem 1977;8:479-90.

20. Jaffe RB. Neuroendocrine-metabolic regulation of pregnancy. In: Yen SSC, Jaffe RB, Barbieri RL, eds. Reproductive endocrinology. Physiology, pathophysiology, and clinical management. Philadelphia: WB Saunders Company, 1999:751-811.

21. Rodeck CH, Gill D, Rosenberg DA, Collins WP. Testosterone levels in midtrimester maternal and fetal plasma and amniotic fluid. Prenat Diagn 1985;5:175-80.

22. Graves JA. Genomic imprinting development and disease—Is pre-eclampsia caused by a maternally imprinted gene? Reprod Fertil Dev 1998;10:23-9.

23. Hiby SE, Lough M, Keverne EB, Surani MA, Loke YW, King A. Paternal monoallelic expression of PEG3 in the human placenta. Hum Mol Genet 2001;10:1093-100.

24. Feeney JG. Pre-eclampsia and changed paternity. In: Bonnar J, MacGillivray I, Symonds M, eds. Pregnancy hypertenson. Lancaster, United Kingdom: MTP Press Limited, 1980:41-4.

Address reprint requests to: Johan Arnt Steier, MD, IVF Department, Maternity Clinic, Haukeland University Hospital, NO-5021 Bergen, Norway; E-mail: jste@haukeland.no

Received December 7, 2001.
Received in revised form April 2, 2002.
Accepted April 18, 2002.