Early pregnancy factor
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Background
Early pregnancy factor (EPF) or early conception factor (ECF) is a protein associated with mammalian embryos shortly after fertilization.[1][2] It may be composed of more than one molecule.[3][4] It was first described in 1976.[4]
Detection
Early pregnancy factor is tested for rosette inhibition test. EPF is present in the maternal serum (blood plasma) shortly after fertilization; EPF is also present in cervical mucus[5] and in amniotic fluid.[6]
EPF may be detected in sheep within 72 hours of mating,[7] in mice within 24 hours of mating,[8] and in samples from media surrounding human embryos fertilized in vitro within 48 hours of fertilization[9] (although another study failed to duplicate this finding for in vitro embryos).[10] EPF has been detected as soon as within six hours of mating.[11]
Because the rosette inhibition test for EPF is indirect, substances that have similar effects may confound the test. Pig semen, like EPF, has been shown to inhibit rosette formation - the rosette inhibition test was positive for one day in sows mated with a vasectomized boar, but not in sows similarly stimulated without semen exposure.[12] A number of studies in the years after the discovery of EPF were unable to reproduce the consistent detection of EPF in post-conception females, and the validity of the discovery experiments was questioned.[13] However, progress in characterization of EPF has been made and its existence is well-accepted in the scientific community.[3][14]
Origin and function
Early embryos are not believed to directly produce EPF. Rather, embryos are believed to produce some other chemical that induces the maternal system to create EPF.[15] After implantation, EPF may be produced by the conceptus directly.[10]
EPF is an immunosuppresant. Along with other substances associated with early embryos, EPF believed to play a role in preventing the immune system of the pregnant female from attacking the embryo.[11][16] Injecting anti-EPF antibodies into mice after mating significantly reduced the number of successful pregnancies and number of pups;[17] no effect on growth was seen when mice embryos were cultured in media containing anti-EPF antibodies.[18] While some actions of EPF are the same in all mammals (namely rosette inhibition), other immunosuppresant mechanism vary between species.[19]
In mice, EPF levels are high in early pregnancy, but on day 15 decline to levels found in non-pregnanct mice.[20] In humans, EPF levels are high for about the first twenty weeks, then decline, becoming undetectable within eight weeks of delivery.[21]
Recent research has suggested that EPF may be associated with cell proliferation in a wide variety of biological situations, not just embryo development.[22]
Clinical utility
Pregnancy testing
In 1979, it was suggested that EPF could be used as a marker for a very early pregnancy test, and as a way to monitor the viability of ongoing pregnancies in livestock.[7] Interest in EPF for this purpose has continued,[23] although current test methods have not proved sufficiently accurate for the requirements of livestock management.[2][24]
In humans, modern pregnancy tests detect human chorionic gonadotropin (hCG). hCG is not present until after implantation, which occurs six to twelve days after fertilization.[25] In contrast, EPF is present within hours of fertilization. While several other pre-implantation signals have been identified, EPF is believed to be the earliest possible marker of pregnancy.[8][26] The accuracy of EPF as a pregnancy test in humans has been found to be high by several studies.[27]
Birth control research
EPF may also be used to determine whether pregnancy prevention mechanism of birth control methods act before or after fertilization. A study evaluating EPF levels in women with IUDs concluded that post-fertilization mechanisms contribute significantly to the effectiveness of these devices.[28]
For groups that define pregnancy as beginning with fertilization, birth control methods that have postfertilization mechanisms are abortifacient. There is currently contention over whether hormonal contraception methods have post-fertilization methods, specifically the most popular method - the combined oral contraceptive pill (COCP). The group Pharmicists for Life has called for a large-scale clinical trial to evaluate EPF in women taking COCPs; this would be the most conclusive evidence available to determine whether COCPs have postfertilization mechanisms.[29]
Infertility and early pregnancy loss
EPF is useful when investigating embryo loss prior to implantation. One study in healthy human women seeking pregnancy detected fourteen pregnancies with EPF. Of these, six were lost within ten days of ovulation (43% rate of early conceptus loss).[30]
Use of EPF has been proposed to distinguish infertility caused by failure to conceive versus infertility caused by failure to implant.[31] EPF has also been proposed as a marker of viable pregnancy, more useful in distinguishing ectopic or other nonviable pregnancies than other chemical markers such as hCG and progesterone.[32]
A study of EPF in women taking clomifene to treat infertility found fertilization rates of about 40%-50% per cycle. In cycles where fertilization was detected, nearly 80% resulted in subclinical embryonic loss, a rate much higher than that found in healthy women.[33]
A study of EPF in women undergoing in vitro fertilization (IVF) concluded that, while a significant number of embryos simply failed to implant, an equally significant number of embryos were likely damaged or killed by the transfer process itself. The researchers used these findings to call for more attention to the effective transfer of embryos during IVF procedures.[34]
As a tumour marker
Although almost exclusively associated with pregnancy, EPF-like activity has also been detected in tumors of germ cell origin[35] and in other types of tumors.[36] Its utility as a tumour marker, to evaluate the success of surgical treatment, has been suggested.[37]
References
- ↑ Smart Y, Roberts T, Clancy R, Cripps A (1981). "Early pregnancy factor: its role in mammalian reproduction--research review". Fertil Steril. 35 (4): 397–402. PMID 7011853.
- ↑ 2.0 2.1 Greco C, Vivas A, Bosch R (1992). "Evaluation of the method for early pregnancy factor detection (EPF) in swine. Significance in early pregnancy diagnosis". Acta Physiol Pharmacol Ther Latinoam. 42 (1): 43–50. PMID 1294272.
- ↑ 3.0 3.1 Di Trapani G, Orosco C, Perkins A, Clarke F (1991). "Isolation from human placental extracts of a preparation possessing 'early pregnancy factor' activity and identification of the polypeptide components". Hum Reprod. 6 (3): 450–7. PMID 1955557.
- ↑ 4.0 4.1 Clarke F (1992). "Identification of molecules and mechanisms involved in the 'early pregnancy factor' system". Reprod Fertil Dev. 4 (4): 423–33. PMID 1461993.
- ↑ Cheng S, Zheng Z (2004). "Early pregnancy factor in cervical mucus of pregnant women". Am J Reprod Immunol. 51 (2): 102–5. PMID 14748834.
- ↑ Zheng Z, Qin Z, Ma A, Qiao C, Wang H. "Detection of early pregnancy factor-like activity in human amniotic fluid". Am J Reprod Immunol. 22 (1–2): 9–11. PMID 2346595.
- ↑ 7.0 7.1 Morton H, Clunie G, Shaw F (1979). "A test for early pregnancy in sheep". Res Vet Sci. 26 (2): 261–2. PMID 262615.
- ↑ 8.0 8.1 Cavanagh A, Morton H, Rolfe B, Gidley-Baird A (1982). "Ovum factor: a first signal of pregnancy?". Am J Reprod Immunol. 2 (2): 97–101. PMID 7102890.
- ↑ Smart Y, Cripps A, Clancy R, Roberts T, Lopata A, Shutt D (1981). "Detection of an immunosuppressive factor in human preimplantation embryo cultures". Med J Aust. 1 (2): 78–9. PMID 7231254.
- ↑ 10.0 10.1 Nahhas F, Barnea E. "Human embryonic origin early pregnancy factor before and after implantation". Am J Reprod Immunol. 22 (3–4): 105–8. PMID 2375830.
- ↑ 11.0 11.1 Shaw F, Morton H (1980). "The immunological approach to pregnancy diagnosis: a review". Vet Rec. 106 (12): 268–70. PMID 6966439.
- ↑ Koch E, Ellendorff F (1985). "Detection of activity similar to that of early pregnancy factor after mating sows with a vasectomized boar". J Reprod Fertil. 74 (1): 39–46. PMID 4020773.
- ↑ Chard T, Grudzinskas J (1987). "Early pregnancy factor". Biol Res Pregnancy Perinatol. 8 (2 2D Half): 53–6. PMID 3322417.
- ↑ Cavanagh A (1996). "Identification of early pregnancy factor as chaperonin 10: implications for understanding its role". Rev Reprod. 1 (1): 28–32. PMID 9414435.
- ↑ Orozco C, Perkins T, Clarke F (1986). "Platelet-activating factor induces the expression of early pregnancy factor activity in female mice". J Reprod Fertil. 78 (2): 549–55. PMID 3806515.
Roberts T, Adamson L, Smart Y, Stanger J, Murdoch R (1987). "An evaluation of peripheral blood platelet enumeration as a monitor of fertilization and early pregnancy". Fertil Steril. 47 (5): 848–54. PMID 3569561.
Sueoka K, Dharmarajan A, Miyazaki T, Atlas S, Wallach E (1988). "Platelet activating factor-induced early pregnancy factor activity from the perfused rabbit ovary and oviduct". Am J Obstet Gynecol. 159 (6): 1580–4. PMID 3207134.
Cavanagh A, Morton H, Athanasas-Platsis S, Quinn K, Rolfe B (1991). "Identification of a putative inhibitor of early pregnancy factor in mice". J Reprod Fertil. 91 (1): 239–48. PMID 1995852.
Cavanagh A, Rolfe B, Athanasas-Platsis S, Quinn K, Morton H (1991). "Relationship between early pregnancy factor, mouse embryo-conditioned medium and platelet-activating factor". J Reprod Fertil. 93 (2): 355–65. PMID 1787455. - ↑ Bose R, Cheng H, Sabbadini E, McCoshen J, MaHadevan M, Fleetham J (1989). "Purified human early pregnancy factor from preimplantation embryo possesses immunosuppresive properties". Am J Obstet Gynecol. 160 (4): 954–60. PMID 2712125.
- ↑ Igarashi S (1987). "Significance of early pregnancy factor (EPF) on reproductive immunology". Nippon Sanka Fujinka Gakkai Zasshi. 39 (2): 189–94. PMID 2950188.
Athanasas-Platsis S, Quinn K, Wong T, Rolfe B, Cavanagh A, Morton H (1989). "Passive immunization of pregnant mice against early pregnancy factor causes loss of embryonic viability". J Reprod Fertil. 87 (2): 495–502. PMID 2600905. - ↑ Athanasas-Platsis S, Morton H, Dunglison G, Kaye P (1991). "Antibodies to early pregnancy factor retard embryonic development in mice in vivo". J Reprod Fertil. 92 (2): 443–51. PMID 1886100.
- ↑ Rolfe B, Cavanagh A, Quinn K, Morton H (1988). "Identification of two suppressor factors induced by early pregnancy factor". Clin Exp Immunol. 73 (2): 219–25. PMID 3180511.
- ↑ Takimoto Y, Hishinuma M, Takahashi Y, Kanagawa H (1989). "Detection of early pregnancy factor in superovulated mice". Nippon Juigaku Zasshi. 51 (5): 879–85. PMID 2607739.
- ↑ Qin Z, Zheng Z (1987). "Detection of early pregnancy factor in human sera". Am J Reprod Immunol Microbiol. 13 (1): 15–8. PMID 2436493.
Wang H, Zheng Z (1990). "Detection of early pregnancy factor in fetal sera". Am J Reprod Immunol. 23 (3): 69–72. PMID 2257053. - ↑ Cavanagh A, Morton H (1994). "The purification of early-pregnancy factor to homogeneity from human platelets and identification as chaperonin 10". Eur J Biochem. 222 (2): 551–60. PMID 7912672.
- ↑ Sakonju I, Enomoto S, Kamimura S, Hamana K (1993). "Monitoring bovine embryo viability with early pregnancy factor". J Vet Med Sci. 55 (2): 271–4. PMID 8513008.
- ↑ Sasser R, Ruder C. "Detection of early pregnancy in domestic ruminants". J Reprod Fertil Suppl. 34: 261–71. PMID 3305923.
Gandy B, Tucker W, Ryan P, Williams A, Tucker A, Moore A, Godfrey R, Willard S (2001). "Evaluation of the early conception factor (ECF) test for the detection of nonpregnancy in dairy cattle". Theriogenology. 56 (4): 637–47. PMID 11572444.
Cordoba M, Sartori R, Fricke P (2001). "Assessment of a commercially available early conception factor (ECF) test for determining pregnancy status of dairy cattle". J Dairy Sci. 84 (8): 1884–9. PMID 11518314. - ↑ Wilcox A, Baird D, Weinberg C (1999). "Time of implantation of the conceptus and loss of pregnancy". N Engl J Med. 340 (23): 1796–9. PMID 10362823.
- ↑ Straube W (1989). "Early embryonal signals". Zentralbl Gynakol. 111 (10): 629–33. PMID 2665388.
- ↑ Smart Y, Roberts T, Fraser I, Cripps A, Clancy R (1982). "Validation of the rosette inhibition test for the detection of early pregnancy in women". Fertil Steril. 37 (6): 779–85. PMID 6177559.
Bessho T, Taira S, Ikuma K, Shigeta M, Koyama K, Isojima S (1984). "Detection of early pregnancy factor in the sera of conceived women before nidation". Nippon Sanka Fujinka Gakkai Zasshi. 36 (3): 391–6. PMID 6715922.
Straube W, Tiemann U, Loh M, Schütz M (1989). "Detection of early pregnancy factor (EPF) in pregnant and nonpregnant subjects with the rosette inhibition test". Arch Gynecol Obstet. 246 (3): 181–7. PMID 2619332.
Fan X, Zheng Z (1997). "A study of early pregnancy factor activity in preimplantation". Am J Reprod Immunol. 37 (5): 359–64. PMID 9196793. - ↑ Smart Y, Fraser I, Clancy R, Roberts T, Cripps A (1982). "Early pregnancy factor as a monitor for fertilization in women wearing intrauterine devices". Fertil Steril. 37 (2): 201–4. PMID 6174375.
- ↑ Template:Cite paper
- ↑ Smart Y, Fraser I, Roberts T, Clancy R, Cripps A (1982). "Fertilization and early pregnancy loss in healthy women attempting conception". Clin Reprod Fertil. 1 (3): 177–84. PMID 6196101.
- ↑ Mesrogli M, Maas D, Schneider J (1988). "Early abortion rate in sterility patients: early pregnancy factor as a parameter". Zentralbl Gynakol. 110 (9): 555–61. PMID 3407357.
- ↑ Straube W, Loh M, Leipe S (1988). "Significance of the detection of early pregnancy factor for monitoring normal and disordered early pregnancy". Geburtshilfe Frauenheilkd. 48 (12): 854–8. PMID 2466731.
Gerhard I, Katzer E, Runnebaum B. "The early pregnancy factor (EPF) in pregnancies of women with habitual abortions". Early Hum Dev. 26 (2): 83–92. PMID 1720719.
Shu-Xin H, Zhen-Qun Z (1993). "A study of early pregnancy factor activity in the sera of patients with unexplained spontaneous abortion". Am J Reprod Immunol. 29 (2): 77–81. PMID 8329108.
Shahani S, Moniz C, Bordekar A, Gupta S, Naik K (1994). "Early pregnancy factor as a marker for assessing embryonic viability in threatened and missed abortions". Gynecol Obstet Invest. 37 (2): 73–6. PMID 8150373. - ↑ Shahani S, Moniz C, Gokral J, Meherji P (1995). "Early pregnancy factor (EPF) as a marker for detecting subclinical embryonic loss in clomiphene citrate-treated women". Am J Reprod Immunol. 33 (5): 350–3. PMID 7576116.
- ↑ Mesrogli M, Nitsche U, Maas D, Degenhardt F, Dieterle S, Schlösser H (1991). "Rate of early abortion after in vitro fertilization and embryo transfer". Geburtshilfe Frauenheilkd. 51 (9): 688–93. PMID 1720752.
Mesrogli M, Dieterle S (1993). "Embryonic losses after in vitro fertilization and embryo transfer". Acta Obstet Gynecol Scand. 72 (1): 36–8. PMID 8382429. - ↑ Rolfe B, Morton H, Cavanagh A, Gardiner R (1983). "Detection of an early pregnancy factor-like substance in sera of patients with testicular germ cell tumors". Am J Reprod Immunol. 3 (2): 97–100. PMID 6859385.
Mehta A, Shahani S (1987). "Detection of early pregnancy factor-like activity in women with gestational trophoblastic tumors". Am J Reprod Immunol Microbiol. 14 (3): 67–9. PMID 2823620. - ↑ Quinn K, Athanasas-Platsis S, Wong T, Rolfe B, Cavanagh A, Morton H (1990). "Monoclonal antibodies to early pregnancy factor perturb tumour cell growth". Clin Exp Immunol. 80 (1): 100–8. PMID 2323098.
- ↑ Bojahr B, Straube W, Reddemann H (1993). "Case observations on the significance of early pregnancy factor as a tumor marker". Zentralbl Gynakol. 115 (3): 125–8. PMID 7682025.