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Low-dose aspirin use does not improve in vitro fertilization outcomes in poor responders
Low-dose aspirin use does not improve in vitro fertilization outcomes in poor responders John L. Frattarelli, M.D.,a Grant D. E. McWilliams, D.O.,b Micah J. Hill, D.O.,b Kathleen A. Miller, B.S.,a and Richard T. Scott, Jr., M.D., H.C.L.D.a a Reproductive Medicine Associates of New Jersey, Morristown, New Jersey; and b Tripler Army Medical Center, Honolulu, Hawaii
Objective: To assess if aspirin improves pregnancy outcome in patients undergoing in vitro fertilization (IVF) with a diagnosis of poor response. Design: Retrospective cohort analysis. Setting: Academic private practice. Patient(s): 1250 poor-responder patients undergoing IVF. Intervention(s): Low-dose (81 mg) aspirin before and during an IVF cycle. Main Outcome Measure(s): Live-birth rate. Result(s): Patients taking 81 mg of aspirin had statistically significantly higher basal antral follicle counts, more days of stimulation, more ampules of gonadotropins used, higher peak estradiol levels, and more follicles that were R14 mm in diameter on the day of human chorionic gonadotropin administration. There was a decrease in the overall fertilization rate for the patients taking aspirin. There was no difference in IVF outcome rates (implantation, pregnancy, loss, or live birth). Conclusion(s): Patients with a diagnosis of poor response who were taking a regimen of 81 of mg aspirin showed an increase in many IVF stimulation parameters and a decrease in fertilization rates. No improvement secondary to 81-mg aspirin intake was found in IVF outcome rates. (Fertil Steril 2008;89:1113–7. 2008 by American Society for Reproductive Medicine.) Key Words: Diminished ovarian reserve, poor responders, IVF outcomes, low-dose aspirin, pregnancy, live birth, ovarian response
Aspirin use is a common adjuvant therapy used in assisted reproductive technologies (ART). There has been conflicting evidence on the use of aspirin to improve pregnancy outcomes, specifically in patients with a history of autoimmune disorders such as antiphospholipid antibody syndrome (1–6). The evidence for aspirin’s action originally described by Vane and Botting (7) has become part of the foundation for helping to explain the mechanism. Aspirin selectively acetylates the hydroxyl group within cyclooxygenase or platelet’s prostaglandin G/H synthase (8). This causes an irreversible decrease in platelet production of prostaglandin G2 (PGG2), decreasing both prostaglandin I2 (PGI2) and thromboxane A2. While PGI2 inhibits platelet aggregation and induces vasodilation, thromboxane A2 is vasoconstrictive and has been thought to cause decreased blood flow in the vasculature. Aspirin has been shown to have a dose-dependent affect on the inhibition of G/H synthase, with 100 mg suppressing the majority of thromboxane A2 (9).
Received March 29, 2007; revised and accepted May 2, 2007. The views expressed in this manuscript are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the U. S. government. Reprint requests: John L. Frattarelli, M.D., Reproductive Medicine Associates of New Jersey, 100 Franklin Square Drive, Suite 200, Somerset, NJ 08873 (FAX: 732-537-0134; E-mail: [email protected]).
0015-0282/08/$34.00 doi:10.1016/j.fertnstert.2007.05.007
Aspirin has been studied in the context of in vitro fertilization (IVF), specifically to investigate whether any change occurs in endometrial thickness, ovarian blood flow, or the quality of oocytes (10–19). The results of these studies are mixed. Some studies that noted increased ovarian blood flow with aspirin use hypothesized that the inhibition of PGG2 decreases platelet’s vasoconstrictive properties by lowering the serum level of thromboxane A2. Such an improvement in blood flow may improve the quality of oocytes, leading to higher implantation, pregnancy, and live-birth rates (16, 17). If low-dose aspirin (81 mg) improves the ovarian environment as suggested, the greatest benefit of adjuvant aspirin therapy may be for women who are poor responders or who have a diagnosis of diminished ovarian reserve. Few studies, with limited powers, have evaluated the efficacy of aspirin use in poor-responder patients undergoing IVF (13–20). Our study focused on whether aspirin therapy improved IVF outcomes in patients with a diagnosis as poor responders. MATERIALS AND METHODS Study Design This retrospective study was designed to evaluate the effect of 81 mg of aspirin on the reproductive outcomes of 1250
Fertility and Sterility Vol. 89, No. 5, May 2008 Copyright ª2008 American Society for Reproductive Medicine, Published by Elsevier Inc.
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women with a diagnosis as poor responders who were undergoing fresh IVF cycles at the Reproductive Medicine Associates of New Jersey. The main outcome measure was live-birth rate. Other outcome measures included the number of follicles R14 mm on day of human chorionic gonadotropin (hCG) administration, peak estradiol level (defined as the level of estradiol on the day of hCG administration), ampules of gonadotropins administered, days of stimulation, number of oocytes retrieved, number of embryos, number of embryos with R7 cells on day 3, number of blastocyst embryos on day 5, and outcome rates (pregnancy, implantation, and loss). Approval was obtained from the Western Institutional Review Board of Olympia, Washington. Patients Records were evaluated for all patients (N ¼ 12,574) from January 2000 to July 2006 who underwent a fresh IVF cycle, with or without intracytoplasmic sperm injection (ICSI), at Reproductive Medicine Associates of New Jersey. From these records, patients were identified who had a diagnosis of poor responders or diminished ovarian reserve (n ¼ 1250). The diagnosis of poor response and/or diminished ovarian reserve was defined as patients having one or more of the following characteristics: [1] diagnosis of diminished ovarian reserve, [2] basal follicle-stimulating hormone (FSH) level >12 mIU/mL, [3] basal antral follicle count of %3 associated with a stimulation follicle number %5, and [4] a history of poor response (%5 oocytes, poor quality oocytes, and/or poor quality embryos). Of this cohort, 417 patients used 81 mg of aspirin, and 833 did not use aspirin during their IVF cycle. Data over the course of the stimulation process were recorded into an electronic database in a prospective manner. No egg recipient, gestational carrier, or frozen embryo transfer cycles were included in this analysis. Patient Treatment Protocols Patients underwent controlled ovarian hyperstimulation generally using a step-down protocol, with a typical initiating dose of 375–450 IU/day of recombinant FSH or a combination of recombinant FSH and low-dose hCG administered at 10–20 IU/day. The methods for down-regulation used included gonadotropin-releasing hormone (GnRH) agonist (leuprolide acetate, Lupron; TAP Pharmaceuticals, Deerfield, IL) either in the luteal protocol or a microdose flare protocol, or intracycle GnRH antagonist administration. Aspirin (81 mg) was started on the patients in the menstrual cycle before the IVF stimulation cycle. Early Pregnancy Monitoring Pregnancy was established by measuring the serum level of b-hCG R5 mIU/mL drawn 14 days after oocyte aspiration. A second level was drawn 2 days later to assess the percentage rise. A rise of less than 66.7% resulted in a third level drawn 2 days later. All patients underwent transvaginal ultrasonography 23 or 24 days after oocyte aspiration (37 or 38 1114
Frattarelli et al.
Aspirin with IVF poor responders
days of gestation) to establish the presence of an intrauterine gestation. Cardiac activity was established 1 week later at 44 or 45 days of gestation. Pregnancies with normal sonographic milestones were followed weekly by blood work and ultrasound until 8 weeks of gestation, when patients were discharged to their obstetrician for continued management. Pregnancies with abnormal milestones were followed and managed more closely, depending on the clinical scenario. Pregnancy outcomes were established via written confirmation obtained from the patient and/or obstetrician. Pregnancies and the accompanying rates were defined as follows. Initial pregnancy was documented by a rising serum hCG concentration on luteal days 14 and 16. Biochemical pregnancies were defined as having a positive pregnancy test on luteal day 14 with a rising titer confirmed by a second hCG level but with loss of the pregnancy before sonographic evidence of the pregnancy. Spontaneous pregnancy loss was defined as a pregnancy loss after sonographic visualization of an intrauterine gestational sac at 6 weeks of gestation. Total loss rate was defined as all patients experiencing a biochemical pregnancy only and those patients with a spontaneous pregnancy loss. The live-birth rate was defined as pregnancies that delivered a viable infant. Implantation rate was calculated by dividing the number of gestational sacs visualized on transvaginal ultrasound at 5 weeks of gestation by the number of embryos transferred. Statistical Analysis For normally distributed data, a Student’s t-test was used to compare the mean values between two groups. For data that were not normally distributed, a Mann-Whitney ranksum test was used to compare the mean values between two groups. Differences in outcome rates were analyzed using a chi-square or two-tailed Fisher exact test, where appropriate. An alpha error of .05 was considered statistically significant for all comparisons. Relative risk (RR) and 95% confidence intervals (CI) are displayed where appropriate. All data are reported as the mean with their associated standard deviation. RESULTS A retrospective analysis was performed on a total of 1250 patients undergoing a fresh IVF cycle. Demographic data and prestimulation parameters between the aspirin and the control groups were compared with respect to the patient’s age, total basal antral follicle count, height, weight, body mass index, and those patients undergoing ICSI (Table 1). Patients who took 81 mg of aspirin for at least 1 month had a higher basal antral follicle count (P<.01); no other statistically significant differences were noted. Stimulation parameters between the patient groups are compared in Table 2. There was no difference between the aspirin and nonaspirin cohorts when comparing the endometrial thickness on day of hCG stimulation; however, in the 81-mg aspirin group there was a statistically significant increase in the peak estradiol level (P<.001), the total days Vol. 89, No. 5, May 2008
TABLE 1 Population demographics and prestimulation parameters in nonaspirin and low-dose aspirin (81 mg) users with poor response. Variables Age (years) Total BAFC Height (inches) Weight (pounds) Body mass index (kg/m2) Percent undergoing ICSI
No aspirin (N [ 833)
81 mg of aspirin (N [ 417)
P value
39.7 3.5 7.1 4.4 64.3 3.1 145.5 32.0 24.8 5.3 409/833 (49.1%)
39.6 3.9 8.0 4.1 64.3 2.9 143.1 29.9 24.3 4.7 183/417 (43.9%)
.71 < .01a .83 .33 .49 .08
Note: Values represent the mean and associated standard deviation except for the ICSI percentage, which is represented by the raw data and percentages. BAFC ¼ basal antral follicle count. a Statistically significant value (P< .05). Frattarelli. Aspirin with IVF poor responders. Fertil Steril 2008.
of stimulation (P<.01), total ampules of gonadotropins used (P<.05), and the number of follicles R14 mm on the day of hCG administration (P<.001). Comparison of embryo data showed no statistically significant difference between the 81-mg aspirin and the nonaspirin users with respect to the number of oocytes retrieved, number of fertilized oocytes on day 1 (two pronuclei), number of embryos transferred, or the number of embryos with R7 cells on day 3 (see Table 2). The pregnancy outcome for the patients with poor response are compared in Table 3. There was no statistically significant difference in implantation rate, pregnancy rate, total loss rate, implantation rate, or live-birth rate. Patients in the nonaspirin group did have a statistically significantly higher fertilization rate (58.2% vs. 54.7%) (P<.01). The power and the number needed to show statistical significance is displayed in Table 3.
DISCUSSION We evaluated the effect of using 81 mg of aspirin in a cohort of 1250 patients with a diagnosis of poor response and/or diminished ovarian reserve. The total number of basal antral follicles was higher in the 81-mg aspirin group. Intuitively, this should translate to improved overall pregnancy outcomes in the 81-mg aspirin group, but the pregnancy outcomes were not improved by the use of aspirin. The 81-mg aspirin cohort did have an increase in the stimulation parameters of peak serum estradiol, total days of stimulation, number of ampules of gonadotropins used for stimulation, and the number of follicles R14mm on day of hCG administration. However, the patients who were not using aspirin had a higher fertilization rate (P<.01). The increase in stimulation parameters might be explained by aspirin’s properties that increase vascular flow (7–9), but no
TABLE 2 Comparison of stimulation parameters and embryo data in nonaspirin and low-dose aspirin (81 mg) users with poor response. Variables
No aspirin (n [ 833)
81 mg aspirin (n [ 417)
P valuea
1281.1 663.7 9.7 2.0 11.7 1.7 50.8 12.7 6.7 3.9
1554.6 990.5 9.9 2.1 12.0 1.7 52.5 13.8 7.7 4.7
< .001a .18 < .01a < .05a .001a
9.0 5.7 5.2 4.0 2.4 2.7 2.6 1.5
9.1 5.7 5.0 3.6 2.1 2.3 2.5 1.6
.81 .76 .13 .50
Peak estradiol (pg/mL) Endometrial thickness (mm) Total days of stimulation Total ampules of gonadotropins Number of follicles R14 mm on day of hCG administration Number of oocytes retrieved Number of 2PN Number of R7 cells on day 3 Number of embryos transferred
Note: Values represent the mean and associated standard deviation. 2PN ¼ two pronuclei; number of fertilized oocytes on day 1 of embryo development. a Statistically significant value (P< .05). Frattarelli. Aspirin with IVF poor responders. Fertil Steril 2008.
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21,133 24,823 NA 17,420 255,400
Recently, studies have suggested that aspirin is not as beneficial as originally thought (13, 14, 18–22). Hurst et al. (14) found that after oocyte retrieval patients on aspirin had a decrease in implantation rate. This was postulated to come from aspirin’s properties of prostaglandin inhibition, in which implantation might be compromised. Other investigators have also shown a similar trend toward improvement in nonaspirin cohorts (20). Likewise, we also noted a slight decrease in the implantation rates for patients using aspirin. Poor pregnancy outcomes in patients with diminished ovarian reserve result from an intrinsic defect in the oocyte. Although aspirin use may improve blood supply to the ovaries, there is evidence for an increased incidence of apoptic granulosa cells within those oocytes harvested from patients taking aspirin (18). Many studies comparing aspirin and nonaspirin users have shown no difference with respect to the number of mature follicles, fertilization rate, ovarian responsiveness, or pregnancy rates, but these studies may have been hampered by insufficient power (13, 19, 21, 22). Our findings are consistent with the earlier studies. In contrast, other studies have shown improvement in clinical pregnancy and livebirth rates by using adjuvant therapy (15, 23). A recent study evaluated a large number of donor oocyte cycles and reported that the use of adjuvant therapy did not statistically significantly improve ultrasonographic endometrial thickness; however, the use of adjuvant therapy may have improved endometrial receptivity, as demonstrated by improved outcome rates in patients undergoing ART (15).
Frattarelli. Aspirin with IVF poor responders. Fertil Steril 2008.
Note: Values represent raw data (percent). a Statistically significant value (P< .05).
0.15 0.07 NA 0.12 0.06 0.92 (0.76, 1.1) 0.94 (0.71, 1.24) 0.94 (0.90, 0.98) 0.93, (0.77, 1.12) 0.97 (0.75, 1.25) .35 .65 < .01a .42 .79 134/742 (18.1) 44/116 (37.9) 1476/2698 (54.7) 116/417 (27.8) 72/417 (17.3)
Frattarelli et al.
Implantation rate Total loss rate Fertilization rate Pregnancy rate Live-birth rate
282/1429 (19.7) 101/250 (40.6) 2886/4955 (58.2) 250/833 (30.0) 149/833 (17.9)
RR (95% CI) Aspirin Variables
No aspirin
P value
Power
Number needed to show statistical significance
Pregnancy outcomes for the poor responders group, which was further subdivided into patients who received aspirin (81 mg) and those who did not receive aspirin.
TABLE 3 1116
improvement in overall IVF pregnancy outcome was noted in this large cohort of patients.
Aspirin with IVF poor responders
Weaknesses of our study include its retrospective nature. Large-scale, prospective, randomized trials are difficult to conduct in IVF patients, which makes retrospective studies more functional for obtaining the necessary power to evaluate differences in treatment outcomes. In this setting, selection bias could have been introduced by the clinician’s and/or the patient’s preference to treat or be treated with 81 mg of aspirin. Our analysis showed that the two cohorts were similar in critical baseline characteristics, minimizing but not excluding the possibility of bias. Strengths of the study include the large population pool and the fact that the data were derived from a prospective database; therefore, no chart review was necessary, and no patients were lost to follow-up evaluation. This decreases the possibility of information biases. Patients with a diagnosis of poor response who took 81 mg of aspirin during their IVF cycle were associated with an increase in basal antral follicles, peak estradiol levels, days of stimulation, and total gonadotropin use. In contrast, a decrease in fertilization rates was noted in aspirin users. Aspirin’s effects on ovarian blood flow may increase basal antral follicle count and IVF stimulation parameters, but this may be offset by aspirin’s possible inhibition of prostaglandins and potential decrease in implantation rates. These data do not support a beneficial effect of aspirin use as an Vol. 89, No. 5, May 2008
adjuvant therapy in IVF cycles for patients with poor response and/or diminished ovarian reserve.
13.
REFERENCES 1. Kutteh WH, Yetman DL, Chantilis SJ, Crain J. Effect of antiphospholipid antibodies in women undergoing in-vitro fertilization: role of heparin and aspirin. Hum Reprod 1997;12:1171–5. 2. Hasegawa I, Yamanoto Y, Suzuki M, Murakawa H, Kurabavashi T, Takakuwa K, Tanaka K. Prednisolone plus low-dose aspirin improves the implantation rate in women with autoimmune conditions who are undergoing in vitro fertilization. Fertil Steril 1998;70:1044–8. 3. Sher G, Feinman M, Zouves C, Kuttner G, Maassarani G, Salem R, et al. High fecundity rates following in-vitro fertilization and embryo transfer in antiphospholipid antibody seropositive women treated with heparin and aspirin. Hum Reprod 1994;9:2278–83. 4. Chilcott IT, Maragara R, Cohen H, Rai R, Skull J, Pickering W, Regan L. Pregnancy outcome is not affected by antiphospholipid antibody status in women referred for in vitro fertilization. Fertil Steril 2000;73:526–30. 5. Stern C, Chamley L, Norris H, Hale L, Baker HW. A randomized, double-blind, placebo-controlled trial of heparin and aspirin for women with in vitro fertilization implantation failure and antiphospholipid or antinuclear antibodies. Fertil Steril 2003;80:376–83. 6. Geva E, Amit A, Lerner-Geva L, Yaron Y, Daniel Y, Schwartz T, et al. Prednisone and aspirin improve pregnancy rate in patients with reproductive failure and autoimmune antibodies: a prospective study. Am J Reprod Immunol 2000;43:36–40. 7. Vane JR, Botting RM. The mechanism of action of aspirin. Thromb Res 2003;110:255–8. 8. Patrono C. Aspirin as an antiplatelet drug. N Engl J Med 1994;330:1287–94. 9. Patrignani P, Filabozzi P, Patrono C. Selective cumulative inhibition of platelet thromboxane production by low-dose aspirin in healthy subjects. J Clin Invest 1982;69:1366–72. 10. Weckstein LN, Jacobson A, Galen D, Hampton K, Hammel J. Low-dose aspirin for oocyte donation recipients with a thin endometrium: prospective randomized study. Fertil Steril 1997;68:927–30. 11. Wada I, Hsu CC, Williams G, Macnamee MC, Brinsden PR. The benefits of low-dose aspirin therapy in women with impaired uterine perfusion during assisted conception. Hum Reprod 1994;9:1954–7. 12. Tassa JM, Marshburn PB, Papadakis MA, Loeb TA, Matthews MM, Hurst BS. Low-dose aspirin does not improve ovarian stimulation, endo-
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metrial response, or pregnancy rates for in vitro fertilization. Fertil Steril 2002;78:S257–8. Lok IH, Yip SK, Cheung LP, Yin Leung PH, Haines CJ. Adjuvant lowdose aspirin therapy in poor responders undergoing in vitro fertilization: a prospective, randomized, double-blind, placebo-controlled trial. Fertil Steril 2004;81:556–61. Hurst BS, Bhojwani JT, Marshburn PB, Papadakis MA, Loeb TA, Matthews ML. Low-dose aspirin does not improve ovarian stimulation, endometrial response, or pregnancy rates for in vitro fertilization. J Exp Clin Assist Reprod 2005;2:8. Frattarelli JL, Miller BT, Scott RT Jr. Adjuvant therapy enhances endometrial receptivity in patients undergoing assisted reproduction. Reprod Biomed Online 2006;12:722–9. Rubinstein M, Marazzi A, Polak de Fried E. Low dose aspirin treatment improves implantation and pregnancy rates in IVF patients: a prospective, randomized, double blind study. Fertil Steril 1997;67:S49–50. Rubinstein M, Marazzi A, Polak de Fried E. Low-dose aspirin treatment improves ovarian responsiveness, uterine and ovarian blood flow velocity, implantation, and pregnancy rates in patients undergoing in vitro fertilization: a prospective, randomized, double-blind placebo-controlled assay. Fertil Steril 1999;71:825–9. Saito H, Kaneko T, Kawachiya S, Du B, Ishida GM, Kurachi H. Effects of aspirin on the oocyte quality [abstract]. Fertil Steril 2001;76: S131. Pakkila M, Rasanen J, Heinonen S, Tinkanen H, Tuomivaara L, Makikallio K, et al. Low-dose aspirin does not improve ovarian responsiveness or pregnancy rate in IVF and ICSI patients: a randomized, placebo-controlled double-blind study. Hum Reprod 2005;20:2211–4. Scoccia H, Puccini M, Horlick N, Winston N. Advancing maternal age and low-dose aspirin effect in poor responders undergoing in vitro fertilization. Fertil Steril 2005;84:S248. Zhang L, Marynick SP, Putman JM, Pinto AB. Low-dose aspirin administration during ovarian stimulation adversely influences pregnancy outcome in in-vitro fertilization/embryo transfer (IVF/ET) patients [abstract]. Fertil Steril 2005;83:S14. Van Dooren IM, Schoot BC, Dargel E, Maas P. Low-dose aspirin demonstrates no positive effect on clinical results in the first in vitro fertilization (IVF) cycle [abstract]. Fertil Steril 2004;82:S18. Waldenstrom U, Hellberg D, Nilsson S. Low-dose aspirin in a short regimen as standard treatment in in vitro fertilization: a randomized, prospective study. Fertil Steril 2004;81:1560–4.
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Objective: To assess if aspirin improves pregnancy outcome in patients undergoing in vitro fertilization (IVF) with a diagnosis of poor response. Design: Retrospective cohort analysis. Setting: Academic private practice. Patient(s): 1250 poor-responder patients undergoing IVF. Intervention(s): Low-dose (81 mg) aspirin before and during an IVF cycle. Main Outcome Measure(s): Live-birth rate. Result(s): Patients taking 81 mg of aspirin had statistically significantly higher basal antral follicle counts, more days of stimulation, more ampules of gonadotropins used, higher peak estradiol levels, and more follicles that were R14 mm in diameter on the day of human chorionic gonadotropin administration. There was a decrease in the overall fertilization rate for the patients taking aspirin. There was no difference in IVF outcome rates (implantation, pregnancy, loss, or live birth). Conclusion(s): Patients with a diagnosis of poor response who were taking a regimen of 81 of mg aspirin showed an increase in many IVF stimulation parameters and a decrease in fertilization rates. No improvement secondary to 81-mg aspirin intake was found in IVF outcome rates. (Fertil Steril 2008;89:1113–7. 2008 by American Society for Reproductive Medicine.) Key Words: Diminished ovarian reserve, poor responders, IVF outcomes, low-dose aspirin, pregnancy, live birth, ovarian response
Aspirin use is a common adjuvant therapy used in assisted reproductive technologies (ART). There has been conflicting evidence on the use of aspirin to improve pregnancy outcomes, specifically in patients with a history of autoimmune disorders such as antiphospholipid antibody syndrome (1–6). The evidence for aspirin’s action originally described by Vane and Botting (7) has become part of the foundation for helping to explain the mechanism. Aspirin selectively acetylates the hydroxyl group within cyclooxygenase or platelet’s prostaglandin G/H synthase (8). This causes an irreversible decrease in platelet production of prostaglandin G2 (PGG2), decreasing both prostaglandin I2 (PGI2) and thromboxane A2. While PGI2 inhibits platelet aggregation and induces vasodilation, thromboxane A2 is vasoconstrictive and has been thought to cause decreased blood flow in the vasculature. Aspirin has been shown to have a dose-dependent affect on the inhibition of G/H synthase, with 100 mg suppressing the majority of thromboxane A2 (9).
Received March 29, 2007; revised and accepted May 2, 2007. The views expressed in this manuscript are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the U. S. government. Reprint requests: John L. Frattarelli, M.D., Reproductive Medicine Associates of New Jersey, 100 Franklin Square Drive, Suite 200, Somerset, NJ 08873 (FAX: 732-537-0134; E-mail: [email protected]).
0015-0282/08/$34.00 doi:10.1016/j.fertnstert.2007.05.007
Aspirin has been studied in the context of in vitro fertilization (IVF), specifically to investigate whether any change occurs in endometrial thickness, ovarian blood flow, or the quality of oocytes (10–19). The results of these studies are mixed. Some studies that noted increased ovarian blood flow with aspirin use hypothesized that the inhibition of PGG2 decreases platelet’s vasoconstrictive properties by lowering the serum level of thromboxane A2. Such an improvement in blood flow may improve the quality of oocytes, leading to higher implantation, pregnancy, and live-birth rates (16, 17). If low-dose aspirin (81 mg) improves the ovarian environment as suggested, the greatest benefit of adjuvant aspirin therapy may be for women who are poor responders or who have a diagnosis of diminished ovarian reserve. Few studies, with limited powers, have evaluated the efficacy of aspirin use in poor-responder patients undergoing IVF (13–20). Our study focused on whether aspirin therapy improved IVF outcomes in patients with a diagnosis as poor responders. MATERIALS AND METHODS Study Design This retrospective study was designed to evaluate the effect of 81 mg of aspirin on the reproductive outcomes of 1250
Fertility and Sterility Vol. 89, No. 5, May 2008 Copyright ª2008 American Society for Reproductive Medicine, Published by Elsevier Inc.
1113
women with a diagnosis as poor responders who were undergoing fresh IVF cycles at the Reproductive Medicine Associates of New Jersey. The main outcome measure was live-birth rate. Other outcome measures included the number of follicles R14 mm on day of human chorionic gonadotropin (hCG) administration, peak estradiol level (defined as the level of estradiol on the day of hCG administration), ampules of gonadotropins administered, days of stimulation, number of oocytes retrieved, number of embryos, number of embryos with R7 cells on day 3, number of blastocyst embryos on day 5, and outcome rates (pregnancy, implantation, and loss). Approval was obtained from the Western Institutional Review Board of Olympia, Washington. Patients Records were evaluated for all patients (N ¼ 12,574) from January 2000 to July 2006 who underwent a fresh IVF cycle, with or without intracytoplasmic sperm injection (ICSI), at Reproductive Medicine Associates of New Jersey. From these records, patients were identified who had a diagnosis of poor responders or diminished ovarian reserve (n ¼ 1250). The diagnosis of poor response and/or diminished ovarian reserve was defined as patients having one or more of the following characteristics: [1] diagnosis of diminished ovarian reserve, [2] basal follicle-stimulating hormone (FSH) level >12 mIU/mL, [3] basal antral follicle count of %3 associated with a stimulation follicle number %5, and [4] a history of poor response (%5 oocytes, poor quality oocytes, and/or poor quality embryos). Of this cohort, 417 patients used 81 mg of aspirin, and 833 did not use aspirin during their IVF cycle. Data over the course of the stimulation process were recorded into an electronic database in a prospective manner. No egg recipient, gestational carrier, or frozen embryo transfer cycles were included in this analysis. Patient Treatment Protocols Patients underwent controlled ovarian hyperstimulation generally using a step-down protocol, with a typical initiating dose of 375–450 IU/day of recombinant FSH or a combination of recombinant FSH and low-dose hCG administered at 10–20 IU/day. The methods for down-regulation used included gonadotropin-releasing hormone (GnRH) agonist (leuprolide acetate, Lupron; TAP Pharmaceuticals, Deerfield, IL) either in the luteal protocol or a microdose flare protocol, or intracycle GnRH antagonist administration. Aspirin (81 mg) was started on the patients in the menstrual cycle before the IVF stimulation cycle. Early Pregnancy Monitoring Pregnancy was established by measuring the serum level of b-hCG R5 mIU/mL drawn 14 days after oocyte aspiration. A second level was drawn 2 days later to assess the percentage rise. A rise of less than 66.7% resulted in a third level drawn 2 days later. All patients underwent transvaginal ultrasonography 23 or 24 days after oocyte aspiration (37 or 38 1114
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Aspirin with IVF poor responders
days of gestation) to establish the presence of an intrauterine gestation. Cardiac activity was established 1 week later at 44 or 45 days of gestation. Pregnancies with normal sonographic milestones were followed weekly by blood work and ultrasound until 8 weeks of gestation, when patients were discharged to their obstetrician for continued management. Pregnancies with abnormal milestones were followed and managed more closely, depending on the clinical scenario. Pregnancy outcomes were established via written confirmation obtained from the patient and/or obstetrician. Pregnancies and the accompanying rates were defined as follows. Initial pregnancy was documented by a rising serum hCG concentration on luteal days 14 and 16. Biochemical pregnancies were defined as having a positive pregnancy test on luteal day 14 with a rising titer confirmed by a second hCG level but with loss of the pregnancy before sonographic evidence of the pregnancy. Spontaneous pregnancy loss was defined as a pregnancy loss after sonographic visualization of an intrauterine gestational sac at 6 weeks of gestation. Total loss rate was defined as all patients experiencing a biochemical pregnancy only and those patients with a spontaneous pregnancy loss. The live-birth rate was defined as pregnancies that delivered a viable infant. Implantation rate was calculated by dividing the number of gestational sacs visualized on transvaginal ultrasound at 5 weeks of gestation by the number of embryos transferred. Statistical Analysis For normally distributed data, a Student’s t-test was used to compare the mean values between two groups. For data that were not normally distributed, a Mann-Whitney ranksum test was used to compare the mean values between two groups. Differences in outcome rates were analyzed using a chi-square or two-tailed Fisher exact test, where appropriate. An alpha error of .05 was considered statistically significant for all comparisons. Relative risk (RR) and 95% confidence intervals (CI) are displayed where appropriate. All data are reported as the mean with their associated standard deviation. RESULTS A retrospective analysis was performed on a total of 1250 patients undergoing a fresh IVF cycle. Demographic data and prestimulation parameters between the aspirin and the control groups were compared with respect to the patient’s age, total basal antral follicle count, height, weight, body mass index, and those patients undergoing ICSI (Table 1). Patients who took 81 mg of aspirin for at least 1 month had a higher basal antral follicle count (P<.01); no other statistically significant differences were noted. Stimulation parameters between the patient groups are compared in Table 2. There was no difference between the aspirin and nonaspirin cohorts when comparing the endometrial thickness on day of hCG stimulation; however, in the 81-mg aspirin group there was a statistically significant increase in the peak estradiol level (P<.001), the total days Vol. 89, No. 5, May 2008
TABLE 1 Population demographics and prestimulation parameters in nonaspirin and low-dose aspirin (81 mg) users with poor response. Variables Age (years) Total BAFC Height (inches) Weight (pounds) Body mass index (kg/m2) Percent undergoing ICSI
No aspirin (N [ 833)
81 mg of aspirin (N [ 417)
P value
39.7 3.5 7.1 4.4 64.3 3.1 145.5 32.0 24.8 5.3 409/833 (49.1%)
39.6 3.9 8.0 4.1 64.3 2.9 143.1 29.9 24.3 4.7 183/417 (43.9%)
.71 < .01a .83 .33 .49 .08
Note: Values represent the mean and associated standard deviation except for the ICSI percentage, which is represented by the raw data and percentages. BAFC ¼ basal antral follicle count. a Statistically significant value (P< .05). Frattarelli. Aspirin with IVF poor responders. Fertil Steril 2008.
of stimulation (P<.01), total ampules of gonadotropins used (P<.05), and the number of follicles R14 mm on the day of hCG administration (P<.001). Comparison of embryo data showed no statistically significant difference between the 81-mg aspirin and the nonaspirin users with respect to the number of oocytes retrieved, number of fertilized oocytes on day 1 (two pronuclei), number of embryos transferred, or the number of embryos with R7 cells on day 3 (see Table 2). The pregnancy outcome for the patients with poor response are compared in Table 3. There was no statistically significant difference in implantation rate, pregnancy rate, total loss rate, implantation rate, or live-birth rate. Patients in the nonaspirin group did have a statistically significantly higher fertilization rate (58.2% vs. 54.7%) (P<.01). The power and the number needed to show statistical significance is displayed in Table 3.
DISCUSSION We evaluated the effect of using 81 mg of aspirin in a cohort of 1250 patients with a diagnosis of poor response and/or diminished ovarian reserve. The total number of basal antral follicles was higher in the 81-mg aspirin group. Intuitively, this should translate to improved overall pregnancy outcomes in the 81-mg aspirin group, but the pregnancy outcomes were not improved by the use of aspirin. The 81-mg aspirin cohort did have an increase in the stimulation parameters of peak serum estradiol, total days of stimulation, number of ampules of gonadotropins used for stimulation, and the number of follicles R14mm on day of hCG administration. However, the patients who were not using aspirin had a higher fertilization rate (P<.01). The increase in stimulation parameters might be explained by aspirin’s properties that increase vascular flow (7–9), but no
TABLE 2 Comparison of stimulation parameters and embryo data in nonaspirin and low-dose aspirin (81 mg) users with poor response. Variables
No aspirin (n [ 833)
81 mg aspirin (n [ 417)
P valuea
1281.1 663.7 9.7 2.0 11.7 1.7 50.8 12.7 6.7 3.9
1554.6 990.5 9.9 2.1 12.0 1.7 52.5 13.8 7.7 4.7
< .001a .18 < .01a < .05a .001a
9.0 5.7 5.2 4.0 2.4 2.7 2.6 1.5
9.1 5.7 5.0 3.6 2.1 2.3 2.5 1.6
.81 .76 .13 .50
Peak estradiol (pg/mL) Endometrial thickness (mm) Total days of stimulation Total ampules of gonadotropins Number of follicles R14 mm on day of hCG administration Number of oocytes retrieved Number of 2PN Number of R7 cells on day 3 Number of embryos transferred
Note: Values represent the mean and associated standard deviation. 2PN ¼ two pronuclei; number of fertilized oocytes on day 1 of embryo development. a Statistically significant value (P< .05). Frattarelli. Aspirin with IVF poor responders. Fertil Steril 2008.
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21,133 24,823 NA 17,420 255,400
Recently, studies have suggested that aspirin is not as beneficial as originally thought (13, 14, 18–22). Hurst et al. (14) found that after oocyte retrieval patients on aspirin had a decrease in implantation rate. This was postulated to come from aspirin’s properties of prostaglandin inhibition, in which implantation might be compromised. Other investigators have also shown a similar trend toward improvement in nonaspirin cohorts (20). Likewise, we also noted a slight decrease in the implantation rates for patients using aspirin. Poor pregnancy outcomes in patients with diminished ovarian reserve result from an intrinsic defect in the oocyte. Although aspirin use may improve blood supply to the ovaries, there is evidence for an increased incidence of apoptic granulosa cells within those oocytes harvested from patients taking aspirin (18). Many studies comparing aspirin and nonaspirin users have shown no difference with respect to the number of mature follicles, fertilization rate, ovarian responsiveness, or pregnancy rates, but these studies may have been hampered by insufficient power (13, 19, 21, 22). Our findings are consistent with the earlier studies. In contrast, other studies have shown improvement in clinical pregnancy and livebirth rates by using adjuvant therapy (15, 23). A recent study evaluated a large number of donor oocyte cycles and reported that the use of adjuvant therapy did not statistically significantly improve ultrasonographic endometrial thickness; however, the use of adjuvant therapy may have improved endometrial receptivity, as demonstrated by improved outcome rates in patients undergoing ART (15).
Frattarelli. Aspirin with IVF poor responders. Fertil Steril 2008.
Note: Values represent raw data (percent). a Statistically significant value (P< .05).
0.15 0.07 NA 0.12 0.06 0.92 (0.76, 1.1) 0.94 (0.71, 1.24) 0.94 (0.90, 0.98) 0.93, (0.77, 1.12) 0.97 (0.75, 1.25) .35 .65 < .01a .42 .79 134/742 (18.1) 44/116 (37.9) 1476/2698 (54.7) 116/417 (27.8) 72/417 (17.3)
Frattarelli et al.
Implantation rate Total loss rate Fertilization rate Pregnancy rate Live-birth rate
282/1429 (19.7) 101/250 (40.6) 2886/4955 (58.2) 250/833 (30.0) 149/833 (17.9)
RR (95% CI) Aspirin Variables
No aspirin
P value
Power
Number needed to show statistical significance
Pregnancy outcomes for the poor responders group, which was further subdivided into patients who received aspirin (81 mg) and those who did not receive aspirin.
TABLE 3 1116
improvement in overall IVF pregnancy outcome was noted in this large cohort of patients.
Aspirin with IVF poor responders
Weaknesses of our study include its retrospective nature. Large-scale, prospective, randomized trials are difficult to conduct in IVF patients, which makes retrospective studies more functional for obtaining the necessary power to evaluate differences in treatment outcomes. In this setting, selection bias could have been introduced by the clinician’s and/or the patient’s preference to treat or be treated with 81 mg of aspirin. Our analysis showed that the two cohorts were similar in critical baseline characteristics, minimizing but not excluding the possibility of bias. Strengths of the study include the large population pool and the fact that the data were derived from a prospective database; therefore, no chart review was necessary, and no patients were lost to follow-up evaluation. This decreases the possibility of information biases. Patients with a diagnosis of poor response who took 81 mg of aspirin during their IVF cycle were associated with an increase in basal antral follicles, peak estradiol levels, days of stimulation, and total gonadotropin use. In contrast, a decrease in fertilization rates was noted in aspirin users. Aspirin’s effects on ovarian blood flow may increase basal antral follicle count and IVF stimulation parameters, but this may be offset by aspirin’s possible inhibition of prostaglandins and potential decrease in implantation rates. These data do not support a beneficial effect of aspirin use as an Vol. 89, No. 5, May 2008
adjuvant therapy in IVF cycles for patients with poor response and/or diminished ovarian reserve.
13.
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