- Email: [email protected]
The risk of cytogenetic abnormalities in the late first trimester of pregnancies conceived through assisted reproduction
INFERTILITY The risk of cytogenetic abnormalities in the late first trimester of pregnancies conceived through assisted reproduction Deirdre A. Conway, M.D.,a,b Satin S. Patel, M.D.,a Jennifer Liem, D.O.,a Kenneth J. Fan, B.S.,a Ray Jalian, B.S.,a John Williams, III, M.D.,a,b and Margareta D. Pisarska, M.D.a,b a
Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center; and b Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, California
Objective: To determine if pregnancies conceived through infertility treatment are at increased risk of cytogenetic abnormalities in the late first trimester compared with spontaneously conceived pregnancies, or if there is increased risk when comparing less invasive infertility treatment (in vivo group) to in vitro fertilization (in vitro group). Design: Retrospective case-controlled study. Setting: University hospital. Patient(s): A total of 1,606 women who spontaneously conceived and 559 women who conceived through infertility treatment undergoing chorionic villus sampling (CVS). Intervention(s): None. Main Outcome Measure(s): Cytogenetic abnormalities diagnosed by CVS. Result(s): No difference in cytogenetic abnormalities was found when comparing spontaneously conceived pregnancies to those conceived through infertility treatment (7.0% versus 5.4%). We also found no difference in the prevalence of cytogenetic abnormalities when comparing in vivo and in vitro fertilization subgroups (4.7% versus 5.8%). Finally, no difference was found when comparing the prevalence of different types of cytogenetic abnormalities between groups. Conclusion(s): Infertility treatment does not increase the risk of carrying a cytogenetically abnormal fetus in the late first trimester, nor does it increase the preponderance for any specific type of abnormality. (Fertil Steril 2011;95:503–6. 2011 by American Society for Reproductive Medicine.) Key Words: Infertility, assisted reproductive technology, cytogenetic abnormality
With an increasing number of couples delaying childbearing in the United States, infertility is on the rise, affecting 7.3 million couples or 12% of the reproductive-age population (Centers for Disease Control [CDC] National Survey of Family Growth, 2002). As a result, the utilization of infertility treatment is also increasing, with assisted reproductive technology (ART) accounting for the birth of 57,564 or >1% of infants in the U.S. in 2007 (CDC 2007). Options available for treatment of couples with infertility range from less aggressive modalities, including clomiphene citrate, controlled ovarian hyperstimulation with gonadotropins, and intrauterine insemination (IUI) of sperm, to more aggressive treatment, namely, in vitro fertilization (IVF). Although the success of ART Received June 1, 2010; revised September 11, 2010; accepted September 15, 2010; published online October 14, 2010. D.A.C. has nothing to disclose. S.S.P. has nothing to disclose. J.L. has nothing to disclose. K.J.F. has nothing to disclose. R.J. has nothing to disclose. J.W. has nothing to disclose. M.D.P. has nothing to disclose. The first two authors contributed equally to this work. Supported by Helping Hands of Los Angeles (M.D.P.) Reprint requests: Margareta D. Pisarska, M.D., Center for Fertility and Reproductive Medicine, Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, 8635 West Third Street, Suite 160W, Los Angeles, CA 90048 (E-mail: [email protected]).
0015-0282/$36.00 doi:10.1016/j.fertnstert.2010.09.019
continues to improve, there has also been increasing concern regarding the safety of ART and the fetal and maternal outcomes of pregnancies conceived through this treatment. Infertility treatments have been associated with not only latetrimester adverse pregnancy outcomes, such as preeclampsia, placental abruption, placenta previa, preterm labor and delivery, and intrauterine growth restriction (1–7), but also possible increased risk of major birth defects and chromosomal abnormalities (8–11). The cause of this is not known, although possible explanations could involve epigenetic errors or even genetic problems resulting from the infertility treatment. Studies to date have been conflicting regarding the association between assisted reproduction and chromosomal abnormalities, some noting increased risk in pregnancies conceived through infertility treatment (8, 12–16), and others unable to find an association (4, 17–19). Furthermore, many of the studies are limited by evaluating early embryos or miscarriage specimens, both of which do not accurately reflect the true risk in ongoing pregnancies. However, because of the long-term sequelae involved in children born with chromosomal abnormalities, it is a particularly important outcome worthy of a more targeted investigation. Another key factor in understanding the consequences of ART on cytogenetic abnormalities is to determine whether any difference
Fertility and Sterility Vol. 95, No. 2, February 2011 Copyright ª2011 American Society for Reproductive Medicine, Published by Elsevier Inc.
503
FIGURE 1 Percentage of cytogenetic abnormalities by chorionic villus sampling (CVS) between (A) spontaneously conceived and infertility treatment groups and (B) in vivo and in vitro subgroups.
Conway. ART and cytogenetic abnormalities. Fertil Steril 2011.
found is a result of the infertility treatment or inherent to the infertile couple. Regarding birth defects, Olson et al. (10) showed an increased risk in children conceived through IUI, and although that study was not powered to show statistical significance, the authors suggested that it could reflect an inherent risk in the infertile couple, because they did not undergo in vitro fertilization. Therefore, we sought to determine if pregnancies conceived through infertility treatment are at increased risk of cytogenetic abnormalities in the late first trimester by chorionic villus sampling (CVS), compared with spontaneously conceived pregnancies. Furthermore, we compared the risk of cytogenetic abnormalities in pregnancies conceived through less invasive infertility treatments (controlled ovarian hyperstimulation with or without IUI, referred to as the in vivo fertilization group) to pregnancies conceived through IVF (in vitro fertilization group), to determine if in vivo versus in vitro methods play a significant role.
MATERIALS AND METHODS We designed a retrospective case-control study to evaluate all women with singleton pregnancies presenting to our institution for CVS from July 2000 to April 2004. Institutional Review Board approval was obtained at the Cedars-Sinai Medical Center. CVS was performed by one of two highly experienced perinatologists, between 9 and 12 weeks gestational age. The gestational age in days was confirmed by trained sonographers using transvaginal ultrasonography. Depending on operator judgement, a transabdominal or transvaginal route was used to obtain samples. Samples were processed on the premises, and cytogenetic analysis was performed by direct and longterm culture. The cytogenetic analysis for each fetus was reviewed by a team of cytogeneticists. All chromosomal abnormalities were categorized based on the type of defect as follows: autosomal trisomies, autosomal mosaics, inversions, gonosomal trisomies, gonosomal mosaics, translocations, monosomies, and other. Exclusion criteria included women under the age of 35 years, pregnancies conceived through the use of donor oocytes or sperm, zygote intrafallopian transfer (ZIFT) or gamete intrafallopian transfer (GIFT), and women with twins or high-order multiple pregnancies. Women <35 years old were
504
Conway et al.
ART and cytogenetic abnormalities
excluded because they would likely represent a skewed population, more often referred as a result of a known family history of a genetic disorder or abnormal screening results. The study population was then divided into pregnancies conceived spontaneously (n ¼ 1,606) or after receiving infertility treatment (n ¼ 555). Patients in the infertility treatment group were further subcategorized into those who conceived through controlled ovarian hyperstimulation with or without IUI, referred to as the in vivo fertilization group (n ¼ 233), and those who conceived through IVF with or without intracytoplasmic sperm injection (ICSI), referred to as the in vitro fertilization group (n ¼ 326). The mean value for maternal age was calculated for each group. The percentage of cytogenetically abnormal fetuses was also calculated for each group. Differences in means or percentages between groups were compared by using either a t test or the Fisher exact test, respectively. A P value of < .05 was considered to be statistically significant.
RESULTS Data were available for analysis of 1,606 singleton pregnancies of women who conceived spontaneously. After excluding 21 patients who used donor sperm, 15 patients who used donor oocytes, and 7 patients who conceived through GIFT or ZIFT, 559 women were available for analysis in the infertility treatment group. Of the couples that conceived through infertility treatment, 233 conceived through in vivo methods and 326 conceived through in vitro methods. When comparing mean gestational age between groups, the mean maternal ages were 39.0 and 39.4 years in the spontaneously conceived and infertility treatment groups, respectively. This difference was small but statistically significant (P¼.01). No significant difference was found when comparing the mean maternal age of the in vivo and in vitro subgroups, which were 39.4 and 39.5 years, respectively (P¼.34). When comparing the incidence of cytogenetic abnormalities between groups, 112 of 1,606 pregnancies (7.0%) in the spontaneously conceived group had an abnormality compared with 30 of 559 pregnancies (5.4%) in the infertility treatment group (Fig. 1A). Vol. 95, No. 2, February 2011
TABLE 1
TABLE 2
Comparison of the type of cytogenetic abnormality between spontaneously conceived and infertility
Comparison of the type of cytogenetic abnormality between in vivo and in vitro infertility treatment subgroups.
treatment groups.
Cytogenetic abnormality Autosomal trisomies Autosomal mosaics Inversions Translocations Gonosomal trisomies Gonosomal mosaics Monosomies Other
Cytogenetic abnormality
Spontaneous (n [ 112), n (%)
Infertility treatment (n [ 30), n (%)
P value
56 (50.0) 23 (20.5) 3 (7.1) 8 (7.1) 7 (6.3) 4 (3.6) 2 (1.8) 4 (3.6)
18 (60.0) 4 (13.3) 2 (6.7) 1 (3.3) 1 (3.3) 1 (3.3) 0 (0.0) 3 (10.0)
NS NS NS NS NS NS NS NS
Autosomal trisomies Autosomal mosaics Inversions Translocations Gonosomal trisomies Gonosomal mosaics Monosomies Other
In vivo (n [ 11), n (%)
In vitro (n [ 19), n (%)
P value
7 (63.6) 0 (0.0) 1 (9.1) 0 (0.0) 0 (0.0) 1 (9.1) 0 (0.0) 2 (18.2)
10 (52.7) 4 (21.2) 1 (5.2) 1 (5.2) 1 (5.2) 0 (0.0) 0 (0.0) 2 (10.5)
NS NS NS NS NS NS NS NS
Conway. ART and cytogenetic abnormalities. Fertil Steril 2011.
Conway. ART and cytogenetic abnormalities. Fertil Steril 2011.
This difference was not statistically significant (P¼.10). When comparing the infertility treatment subgroups, 11 of 233 pregnancies (4.7%) in the in vivo group and 19 of 326 (5.8%) in the in vitro group were cytogenetically abnormal (Fig. 1B). This difference also did not achieve statistical significance (P¼.45). When comparing the type of cytogenetic abnormality between groups, no significant difference was found between spontaneously conceived and infertility treatment groups (Table 1), or between in vivo and in vitro subgroups (Table 2). Autosomal trisomies were the most common abnormality, accounting for 50% and 60% of abnormities found in the spontaneously conceived and infertility treatment groups, respectively. The second most common abnormality was autosomal mosaicism, accounting for 20.5% and 13.3% of abnormities found in spontaneously conceived and infertility treatment groups, respectively. Less prevalent cytogenetic abnormalities in both the spontaneously conceived and infertility treatment groups included inversions, translocations, gonosomal trisomies, gonosomal mosaics, and monosomies. There were also no significant differences when comparing the prevalence of specific types of cytogenetic abnormalities between in vivo and in vitro subgroups. Autosomal trisomies had the highest prevalence in both groups, accounting for 63.6% and 52.7% of abnormalities in the in vivo and in vitro subgroups, respectively. Although autosomal mosaicism accounted for 21.2% of in vitro–conceived abnormalities and none of the in vivo–conceived abnormalities, this difference did not reach statistical significance.
DISCUSSION We found no difference in cytogenetic abnormalities when comparing spontaneously conceived pregnancies to those conceived through infertility treatment. We also found no difference in the incidence of cytogenetic abnormalities when comparing in vivo and in vitro fertilization subgroups. Finally, no difference was found when comparing the type of cytogenetic abnormality between groups. Thus, our results show that infertility treatment does not increase the risk of a carrying a cytogenetically abnormal fetus in the late first trimester, nor does it increase the preponderance for any specific type of abnormality. Although early investigators reported that ART was safe regarding the incidence of birth defects (20–24), recent and more optimally designed studies have been accumulating data to the contrary (8–10). Fertility and Sterility
Most recently, a large case-control study by Reefhuis et al. (11) found a higher incidence of septal heart defects, cleft lip, and esophageal or anorectal atresia among infants conceived through ART. This has raised concern regarding not only what underlying mechanism could account for this association, but also whether there is an overall increased risk of conceiving a cytogenetically abnormal child. Some investigators have suggested that early embryo aneuploidy and the incidence of embryo mosaicism may be affected by ovarian stimulation regimens in IVF (12, 16). However, those studies were suboptimal owing to methodologic limitations of preimplantation genetic screening using fluorescence in situ hybridization and to a lack of pregnancy outcome data. Furthermore, this concept was refuted by a recent study which found no difference in the rate of mosaicism in CVS specimens at the end of the first trimester in pregnancies spontaneously conceived compared with those conceived through infertility treatment (25). Taking a different approach, other investigators have examined miscarriage specimens of pregnancies conceived through IVF with ICSI and found an increased risk of general chromosomal abnormalities (13, 14). However, none have shown any significant risk with IVF alone when compared with spontaneous conceptions (17–19). These studies also are limited, because they do not reflect ongoing pregnancies, with the specimens coming from pregnancies typically selected out early in the first trimester. The present analysis should more accurately represent the true risk of conceiving a cytogenetically abnormal child, because it was performed in ongoing pregnancies during the late first trimester. Our findings are in contrast to a small study of CVS specimens from pregnancies conceived through ART (15) and to those of a study by Hansen et al. (8), which found an increased risk of chromosomal abnormalities in singletons conceived through ART compared with a spontaneously conceived cohort. However, in the study by Hansen et al., couples conceiving through ART were significantly older than those conceiving spontaneously, which could account for differences in the incidence of cytogenetically abnormal pregnancies. Our conclusions are corroborated by a large prospective multicenter study by Shevell et al. (4), which did not find an increased incidence of fetal chromosomal abnormalities in women who conceived through ART. However, the present study most likely reflects the true risk of pregnancies conceived with infertility treatment, because live birth results may be skewed owing to termination of chromosomally affected pregnancies.
505
Regarding the infertile couple, our results suggest that they do not have an inherently increased risk of conceiving a cytogenetically abnormal child, because there was no difference when comparing pregnancies conceived spontaneously with those conceived through infertility treatment. It also does not appear that in vitro manipulation confers any increased risk, because pregnancies conceived through in vitro treatment had similar risk to those conceived through in vivo treatment modalities. Limitations of the present study are those inherent to any retrospective study and the fact that our database originates from one center in a large western U.S. metropolitan city. Therefore, whether the conclusions of our study can be extended to different patient populations remains to be seen. Finally, sample size limitations preclude us from comparing the incidence of cytogenetic abnormalities between pregnancies conceived through conventional IVF and IVF
with ICSI. Despite this limitation, the fact that the overall risk of a cytogenetically abnormal pregnancy was not increased among all patients with infertility, as well as those undergoing IVF, is encouraging. As the use of ART continues to rise, it is increasingly important to understand the consequences of infertility treatment and the risks to the infertile couple. The outcome of cytogenetic abnormalities is particularly important, owing to the resulting long-term sequelae in children born to these couples. Reassuringly, we have found that couples conceiving through infertility treatment are at the same general risk of carrying a cytogenetically abnormal pregnancy as the general population when diagnosed by CVS in the late first trimester. Despite this, clinicians should continue to offer aneuploidy screening and invasive diagnostic testing to all couples, regardless of the mode of conception.
REFERENCES 1. Tan SL, Doyle P, Campbell S, Beral V, Rizk B, Brindsen P, et al. Obstetric outcome of in vitro fertilization pregnancies compared with normally conceived pregnancies. Am J Obstet Gynecol 1992;167: 778–84. 2. Reubinoff BE, Samueloff A, Ben-Haim M, Friedler S, Schenker JG, Lewin A. Is the obstetric outcome of in vitro fertilized singleton gestations different from natural ones? A controlled study. Fertil Steril 1997;67:1077–83. 3. Jackson RA, Gibson KA, Wu YW, Croughan MS. Perinatal outcomes in singletons following in vitro fertilization: a meta-analysis. Obstet Gynecol 2004;103: 551–63. 4. Shevell T, Malone FD, Vidaver J, Porter TF, Luthy DA, Comstock CH, et al. Assisted reproductive technology and pregnancy outcome. Obstet Gynecol 2005;106(5 pt 1):1039–45. 5. Verlaenen H, Cammu H, Derde MP, Amy JJ. Singleton pregnancy after in vitro fertilization: expectations and outcome. Obstet Gynecol 1995;86:906–10. 6. Reddy UM, Wapner RJ, Rebar RW, Tasca RJ. Infertility, assisted reproductive technology, and adverse pregnancy outcomes: executive summary of a National Institute of Child Health and Human Development workshop. Obstet Gynecol 2007;109:967–77. 7. Schieve LA, Ferre C, Peterson HB, Macaluso M, Reynolds MA, Wright VC. Perinatal outcome among singleton infants conceived through assisted reproductive technology in the United States. Obstet Gynecol 2004;103:1144–53. 8. Hansen M, Kurinczuk JJ, Bower C, Webb S. The risk of major birth defects after intracytoplasmic sperm injection and in vitro fertilization. N Engl J Med 2002;346:725–30.
506
Conway et al.
9. Koivurova S, Hartikainen AL, Gissler M, Hemminki E, Sovio U, Jarvelin MR. Neonatal outcome and congenital malformations in children born after in-vitro fertilization. Hum Reprod 2002;17:1391–8. 10. Olson CK, Keppler-Noreuil KM, Romitti PA, Budelier WT, Ryan G, Sparks AE, et al. In vitro fertilization is associated with an increase in major birth defects. Fertil Steril 2005;84:1308–15. 11. Reefhuis J, Honein MA, Schieve LA, Correa A, Hobbs CA, Rasmussen SA. Assisted reproductive technology and major structural birth defects in the United States. Hum Reprod 2009;24:360–6. 12. Baart EB, Martini E, Eijkemans MJ, Opstal DV, Beckers NG, Verhoeff A, et al. Milder ovarian stimulation for in-vitro fertilization reduces aneuploidy in the human preimplantation embryo: a randomized controlled trial. Hum Reprod 2007;22: 980–8. 13. Lathi RB, Milki AA. Rate of aneuploidy in miscarriages following in vitro fertilization and intracytoplasmic sperm injection. Fertil Steril 2004;81: 1270–2. 14. Retzloff MG, Hornstein MD. Is intracytoplasmic sperm injection safe? Fertil Steril 2003;80:851–9. 15. In’t Veld PA, van Opstal D, van den Berg C, van Ooijen M, Brandenburg H, Pijpers L, et al. Increased incidence of cytogenetic abnormalities in chorionic villus samples from pregnancies established by in vitro fertilization and embryo transfer (IVF-ET). Prenat Diagn 1995;15:975–80. 16. Munne S, Magli C, Adler A, Wright G, de Boer K, Mortimer D, et al. Treatment-related chromosome abnormalities in human embryos. Hum Reprod 1997;12:780–4.
ART and cytogenetic abnormalities
17. Martinez MC, Mendez C, Ferro J, Nicolas M, Serra V, Landeras J. Cytogenetic analysis of early nonviable pregnancies after assisted reproduction treatment. Fertil Steril 2010;93:289–92. 18. Bettio D, Venci A, Levi Setti PE. Chromosomal abnormalities in miscarriages after different assisted reproduction procedures. Placenta 2008;29(Suppl 8). 19. Shields LE, Serafini PC, Schenken RS, Moore CM. Chromosomal analysis of pregnancy losses in patients undergoing assisted reproduction. J Assist Reprod Genet 1992;9:57–60. 20. Rizk B, Doyle P, Tan SL, Rainsbury P, Betts J, Brinsden P, et al. Perinatal outcome and congenital malformations in in-vitro fertilization babies from the Bourn-Hallam group. Hum Reprod 1991;6:1259–64. 21. French In Vitro National (FIVNAT). Pregnancies and births resulting from in vitro fertilization: French national registry, analysis of data 1986 to 1990. Fertil Steril 1995;64:746–56. 22. Olivennes F, Kerbrat V, Rufat P, Blanchet V, Fanchin R, Frydman R. Follow-up of a cohort of 422 children aged 6 to 13 years conceived by in vitro fertilization. Fertil Steril 1997;67:284–9. 23. Tanbo T, Dale PO, Lunde O, Moe N, Abyholm T. Obstetric outcome in singleton pregnancies after assisted reproduction. Obstet Gynecol 1995;86:188–92. 24. Morin NC, Wirth FH, Johnson DH, Frank LM, Presburg HJ, Van de Water VL, et al. Congenital malformations and psychosocial development in children conceived by in vitro fertilization. J Pediatr 1989;115: 222–7. 25. Huang A, Adusumalli J, Patel S, Liem J, Williams III J, Pisarska MD. Prevalence of chromosomal mosaicism in pregnancies from couples with infertility. Fertil Steril 2009;91:2355–60.
Vol. 95, No. 2, February 2011
Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center; and b Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, California
Objective: To determine if pregnancies conceived through infertility treatment are at increased risk of cytogenetic abnormalities in the late first trimester compared with spontaneously conceived pregnancies, or if there is increased risk when comparing less invasive infertility treatment (in vivo group) to in vitro fertilization (in vitro group). Design: Retrospective case-controlled study. Setting: University hospital. Patient(s): A total of 1,606 women who spontaneously conceived and 559 women who conceived through infertility treatment undergoing chorionic villus sampling (CVS). Intervention(s): None. Main Outcome Measure(s): Cytogenetic abnormalities diagnosed by CVS. Result(s): No difference in cytogenetic abnormalities was found when comparing spontaneously conceived pregnancies to those conceived through infertility treatment (7.0% versus 5.4%). We also found no difference in the prevalence of cytogenetic abnormalities when comparing in vivo and in vitro fertilization subgroups (4.7% versus 5.8%). Finally, no difference was found when comparing the prevalence of different types of cytogenetic abnormalities between groups. Conclusion(s): Infertility treatment does not increase the risk of carrying a cytogenetically abnormal fetus in the late first trimester, nor does it increase the preponderance for any specific type of abnormality. (Fertil Steril 2011;95:503–6. 2011 by American Society for Reproductive Medicine.) Key Words: Infertility, assisted reproductive technology, cytogenetic abnormality
With an increasing number of couples delaying childbearing in the United States, infertility is on the rise, affecting 7.3 million couples or 12% of the reproductive-age population (Centers for Disease Control [CDC] National Survey of Family Growth, 2002). As a result, the utilization of infertility treatment is also increasing, with assisted reproductive technology (ART) accounting for the birth of 57,564 or >1% of infants in the U.S. in 2007 (CDC 2007). Options available for treatment of couples with infertility range from less aggressive modalities, including clomiphene citrate, controlled ovarian hyperstimulation with gonadotropins, and intrauterine insemination (IUI) of sperm, to more aggressive treatment, namely, in vitro fertilization (IVF). Although the success of ART Received June 1, 2010; revised September 11, 2010; accepted September 15, 2010; published online October 14, 2010. D.A.C. has nothing to disclose. S.S.P. has nothing to disclose. J.L. has nothing to disclose. K.J.F. has nothing to disclose. R.J. has nothing to disclose. J.W. has nothing to disclose. M.D.P. has nothing to disclose. The first two authors contributed equally to this work. Supported by Helping Hands of Los Angeles (M.D.P.) Reprint requests: Margareta D. Pisarska, M.D., Center for Fertility and Reproductive Medicine, Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, 8635 West Third Street, Suite 160W, Los Angeles, CA 90048 (E-mail: [email protected]).
0015-0282/$36.00 doi:10.1016/j.fertnstert.2010.09.019
continues to improve, there has also been increasing concern regarding the safety of ART and the fetal and maternal outcomes of pregnancies conceived through this treatment. Infertility treatments have been associated with not only latetrimester adverse pregnancy outcomes, such as preeclampsia, placental abruption, placenta previa, preterm labor and delivery, and intrauterine growth restriction (1–7), but also possible increased risk of major birth defects and chromosomal abnormalities (8–11). The cause of this is not known, although possible explanations could involve epigenetic errors or even genetic problems resulting from the infertility treatment. Studies to date have been conflicting regarding the association between assisted reproduction and chromosomal abnormalities, some noting increased risk in pregnancies conceived through infertility treatment (8, 12–16), and others unable to find an association (4, 17–19). Furthermore, many of the studies are limited by evaluating early embryos or miscarriage specimens, both of which do not accurately reflect the true risk in ongoing pregnancies. However, because of the long-term sequelae involved in children born with chromosomal abnormalities, it is a particularly important outcome worthy of a more targeted investigation. Another key factor in understanding the consequences of ART on cytogenetic abnormalities is to determine whether any difference
Fertility and Sterility Vol. 95, No. 2, February 2011 Copyright ª2011 American Society for Reproductive Medicine, Published by Elsevier Inc.
503
FIGURE 1 Percentage of cytogenetic abnormalities by chorionic villus sampling (CVS) between (A) spontaneously conceived and infertility treatment groups and (B) in vivo and in vitro subgroups.
Conway. ART and cytogenetic abnormalities. Fertil Steril 2011.
found is a result of the infertility treatment or inherent to the infertile couple. Regarding birth defects, Olson et al. (10) showed an increased risk in children conceived through IUI, and although that study was not powered to show statistical significance, the authors suggested that it could reflect an inherent risk in the infertile couple, because they did not undergo in vitro fertilization. Therefore, we sought to determine if pregnancies conceived through infertility treatment are at increased risk of cytogenetic abnormalities in the late first trimester by chorionic villus sampling (CVS), compared with spontaneously conceived pregnancies. Furthermore, we compared the risk of cytogenetic abnormalities in pregnancies conceived through less invasive infertility treatments (controlled ovarian hyperstimulation with or without IUI, referred to as the in vivo fertilization group) to pregnancies conceived through IVF (in vitro fertilization group), to determine if in vivo versus in vitro methods play a significant role.
MATERIALS AND METHODS We designed a retrospective case-control study to evaluate all women with singleton pregnancies presenting to our institution for CVS from July 2000 to April 2004. Institutional Review Board approval was obtained at the Cedars-Sinai Medical Center. CVS was performed by one of two highly experienced perinatologists, between 9 and 12 weeks gestational age. The gestational age in days was confirmed by trained sonographers using transvaginal ultrasonography. Depending on operator judgement, a transabdominal or transvaginal route was used to obtain samples. Samples were processed on the premises, and cytogenetic analysis was performed by direct and longterm culture. The cytogenetic analysis for each fetus was reviewed by a team of cytogeneticists. All chromosomal abnormalities were categorized based on the type of defect as follows: autosomal trisomies, autosomal mosaics, inversions, gonosomal trisomies, gonosomal mosaics, translocations, monosomies, and other. Exclusion criteria included women under the age of 35 years, pregnancies conceived through the use of donor oocytes or sperm, zygote intrafallopian transfer (ZIFT) or gamete intrafallopian transfer (GIFT), and women with twins or high-order multiple pregnancies. Women <35 years old were
504
Conway et al.
ART and cytogenetic abnormalities
excluded because they would likely represent a skewed population, more often referred as a result of a known family history of a genetic disorder or abnormal screening results. The study population was then divided into pregnancies conceived spontaneously (n ¼ 1,606) or after receiving infertility treatment (n ¼ 555). Patients in the infertility treatment group were further subcategorized into those who conceived through controlled ovarian hyperstimulation with or without IUI, referred to as the in vivo fertilization group (n ¼ 233), and those who conceived through IVF with or without intracytoplasmic sperm injection (ICSI), referred to as the in vitro fertilization group (n ¼ 326). The mean value for maternal age was calculated for each group. The percentage of cytogenetically abnormal fetuses was also calculated for each group. Differences in means or percentages between groups were compared by using either a t test or the Fisher exact test, respectively. A P value of < .05 was considered to be statistically significant.
RESULTS Data were available for analysis of 1,606 singleton pregnancies of women who conceived spontaneously. After excluding 21 patients who used donor sperm, 15 patients who used donor oocytes, and 7 patients who conceived through GIFT or ZIFT, 559 women were available for analysis in the infertility treatment group. Of the couples that conceived through infertility treatment, 233 conceived through in vivo methods and 326 conceived through in vitro methods. When comparing mean gestational age between groups, the mean maternal ages were 39.0 and 39.4 years in the spontaneously conceived and infertility treatment groups, respectively. This difference was small but statistically significant (P¼.01). No significant difference was found when comparing the mean maternal age of the in vivo and in vitro subgroups, which were 39.4 and 39.5 years, respectively (P¼.34). When comparing the incidence of cytogenetic abnormalities between groups, 112 of 1,606 pregnancies (7.0%) in the spontaneously conceived group had an abnormality compared with 30 of 559 pregnancies (5.4%) in the infertility treatment group (Fig. 1A). Vol. 95, No. 2, February 2011
TABLE 1
TABLE 2
Comparison of the type of cytogenetic abnormality between spontaneously conceived and infertility
Comparison of the type of cytogenetic abnormality between in vivo and in vitro infertility treatment subgroups.
treatment groups.
Cytogenetic abnormality Autosomal trisomies Autosomal mosaics Inversions Translocations Gonosomal trisomies Gonosomal mosaics Monosomies Other
Cytogenetic abnormality
Spontaneous (n [ 112), n (%)
Infertility treatment (n [ 30), n (%)
P value
56 (50.0) 23 (20.5) 3 (7.1) 8 (7.1) 7 (6.3) 4 (3.6) 2 (1.8) 4 (3.6)
18 (60.0) 4 (13.3) 2 (6.7) 1 (3.3) 1 (3.3) 1 (3.3) 0 (0.0) 3 (10.0)
NS NS NS NS NS NS NS NS
Autosomal trisomies Autosomal mosaics Inversions Translocations Gonosomal trisomies Gonosomal mosaics Monosomies Other
In vivo (n [ 11), n (%)
In vitro (n [ 19), n (%)
P value
7 (63.6) 0 (0.0) 1 (9.1) 0 (0.0) 0 (0.0) 1 (9.1) 0 (0.0) 2 (18.2)
10 (52.7) 4 (21.2) 1 (5.2) 1 (5.2) 1 (5.2) 0 (0.0) 0 (0.0) 2 (10.5)
NS NS NS NS NS NS NS NS
Conway. ART and cytogenetic abnormalities. Fertil Steril 2011.
Conway. ART and cytogenetic abnormalities. Fertil Steril 2011.
This difference was not statistically significant (P¼.10). When comparing the infertility treatment subgroups, 11 of 233 pregnancies (4.7%) in the in vivo group and 19 of 326 (5.8%) in the in vitro group were cytogenetically abnormal (Fig. 1B). This difference also did not achieve statistical significance (P¼.45). When comparing the type of cytogenetic abnormality between groups, no significant difference was found between spontaneously conceived and infertility treatment groups (Table 1), or between in vivo and in vitro subgroups (Table 2). Autosomal trisomies were the most common abnormality, accounting for 50% and 60% of abnormities found in the spontaneously conceived and infertility treatment groups, respectively. The second most common abnormality was autosomal mosaicism, accounting for 20.5% and 13.3% of abnormities found in spontaneously conceived and infertility treatment groups, respectively. Less prevalent cytogenetic abnormalities in both the spontaneously conceived and infertility treatment groups included inversions, translocations, gonosomal trisomies, gonosomal mosaics, and monosomies. There were also no significant differences when comparing the prevalence of specific types of cytogenetic abnormalities between in vivo and in vitro subgroups. Autosomal trisomies had the highest prevalence in both groups, accounting for 63.6% and 52.7% of abnormalities in the in vivo and in vitro subgroups, respectively. Although autosomal mosaicism accounted for 21.2% of in vitro–conceived abnormalities and none of the in vivo–conceived abnormalities, this difference did not reach statistical significance.
DISCUSSION We found no difference in cytogenetic abnormalities when comparing spontaneously conceived pregnancies to those conceived through infertility treatment. We also found no difference in the incidence of cytogenetic abnormalities when comparing in vivo and in vitro fertilization subgroups. Finally, no difference was found when comparing the type of cytogenetic abnormality between groups. Thus, our results show that infertility treatment does not increase the risk of a carrying a cytogenetically abnormal fetus in the late first trimester, nor does it increase the preponderance for any specific type of abnormality. Although early investigators reported that ART was safe regarding the incidence of birth defects (20–24), recent and more optimally designed studies have been accumulating data to the contrary (8–10). Fertility and Sterility
Most recently, a large case-control study by Reefhuis et al. (11) found a higher incidence of septal heart defects, cleft lip, and esophageal or anorectal atresia among infants conceived through ART. This has raised concern regarding not only what underlying mechanism could account for this association, but also whether there is an overall increased risk of conceiving a cytogenetically abnormal child. Some investigators have suggested that early embryo aneuploidy and the incidence of embryo mosaicism may be affected by ovarian stimulation regimens in IVF (12, 16). However, those studies were suboptimal owing to methodologic limitations of preimplantation genetic screening using fluorescence in situ hybridization and to a lack of pregnancy outcome data. Furthermore, this concept was refuted by a recent study which found no difference in the rate of mosaicism in CVS specimens at the end of the first trimester in pregnancies spontaneously conceived compared with those conceived through infertility treatment (25). Taking a different approach, other investigators have examined miscarriage specimens of pregnancies conceived through IVF with ICSI and found an increased risk of general chromosomal abnormalities (13, 14). However, none have shown any significant risk with IVF alone when compared with spontaneous conceptions (17–19). These studies also are limited, because they do not reflect ongoing pregnancies, with the specimens coming from pregnancies typically selected out early in the first trimester. The present analysis should more accurately represent the true risk of conceiving a cytogenetically abnormal child, because it was performed in ongoing pregnancies during the late first trimester. Our findings are in contrast to a small study of CVS specimens from pregnancies conceived through ART (15) and to those of a study by Hansen et al. (8), which found an increased risk of chromosomal abnormalities in singletons conceived through ART compared with a spontaneously conceived cohort. However, in the study by Hansen et al., couples conceiving through ART were significantly older than those conceiving spontaneously, which could account for differences in the incidence of cytogenetically abnormal pregnancies. Our conclusions are corroborated by a large prospective multicenter study by Shevell et al. (4), which did not find an increased incidence of fetal chromosomal abnormalities in women who conceived through ART. However, the present study most likely reflects the true risk of pregnancies conceived with infertility treatment, because live birth results may be skewed owing to termination of chromosomally affected pregnancies.
505
Regarding the infertile couple, our results suggest that they do not have an inherently increased risk of conceiving a cytogenetically abnormal child, because there was no difference when comparing pregnancies conceived spontaneously with those conceived through infertility treatment. It also does not appear that in vitro manipulation confers any increased risk, because pregnancies conceived through in vitro treatment had similar risk to those conceived through in vivo treatment modalities. Limitations of the present study are those inherent to any retrospective study and the fact that our database originates from one center in a large western U.S. metropolitan city. Therefore, whether the conclusions of our study can be extended to different patient populations remains to be seen. Finally, sample size limitations preclude us from comparing the incidence of cytogenetic abnormalities between pregnancies conceived through conventional IVF and IVF
with ICSI. Despite this limitation, the fact that the overall risk of a cytogenetically abnormal pregnancy was not increased among all patients with infertility, as well as those undergoing IVF, is encouraging. As the use of ART continues to rise, it is increasingly important to understand the consequences of infertility treatment and the risks to the infertile couple. The outcome of cytogenetic abnormalities is particularly important, owing to the resulting long-term sequelae in children born to these couples. Reassuringly, we have found that couples conceiving through infertility treatment are at the same general risk of carrying a cytogenetically abnormal pregnancy as the general population when diagnosed by CVS in the late first trimester. Despite this, clinicians should continue to offer aneuploidy screening and invasive diagnostic testing to all couples, regardless of the mode of conception.
REFERENCES 1. Tan SL, Doyle P, Campbell S, Beral V, Rizk B, Brindsen P, et al. Obstetric outcome of in vitro fertilization pregnancies compared with normally conceived pregnancies. Am J Obstet Gynecol 1992;167: 778–84. 2. Reubinoff BE, Samueloff A, Ben-Haim M, Friedler S, Schenker JG, Lewin A. Is the obstetric outcome of in vitro fertilized singleton gestations different from natural ones? A controlled study. Fertil Steril 1997;67:1077–83. 3. Jackson RA, Gibson KA, Wu YW, Croughan MS. Perinatal outcomes in singletons following in vitro fertilization: a meta-analysis. Obstet Gynecol 2004;103: 551–63. 4. Shevell T, Malone FD, Vidaver J, Porter TF, Luthy DA, Comstock CH, et al. Assisted reproductive technology and pregnancy outcome. Obstet Gynecol 2005;106(5 pt 1):1039–45. 5. Verlaenen H, Cammu H, Derde MP, Amy JJ. Singleton pregnancy after in vitro fertilization: expectations and outcome. Obstet Gynecol 1995;86:906–10. 6. Reddy UM, Wapner RJ, Rebar RW, Tasca RJ. Infertility, assisted reproductive technology, and adverse pregnancy outcomes: executive summary of a National Institute of Child Health and Human Development workshop. Obstet Gynecol 2007;109:967–77. 7. Schieve LA, Ferre C, Peterson HB, Macaluso M, Reynolds MA, Wright VC. Perinatal outcome among singleton infants conceived through assisted reproductive technology in the United States. Obstet Gynecol 2004;103:1144–53. 8. Hansen M, Kurinczuk JJ, Bower C, Webb S. The risk of major birth defects after intracytoplasmic sperm injection and in vitro fertilization. N Engl J Med 2002;346:725–30.
506
Conway et al.
9. Koivurova S, Hartikainen AL, Gissler M, Hemminki E, Sovio U, Jarvelin MR. Neonatal outcome and congenital malformations in children born after in-vitro fertilization. Hum Reprod 2002;17:1391–8. 10. Olson CK, Keppler-Noreuil KM, Romitti PA, Budelier WT, Ryan G, Sparks AE, et al. In vitro fertilization is associated with an increase in major birth defects. Fertil Steril 2005;84:1308–15. 11. Reefhuis J, Honein MA, Schieve LA, Correa A, Hobbs CA, Rasmussen SA. Assisted reproductive technology and major structural birth defects in the United States. Hum Reprod 2009;24:360–6. 12. Baart EB, Martini E, Eijkemans MJ, Opstal DV, Beckers NG, Verhoeff A, et al. Milder ovarian stimulation for in-vitro fertilization reduces aneuploidy in the human preimplantation embryo: a randomized controlled trial. Hum Reprod 2007;22: 980–8. 13. Lathi RB, Milki AA. Rate of aneuploidy in miscarriages following in vitro fertilization and intracytoplasmic sperm injection. Fertil Steril 2004;81: 1270–2. 14. Retzloff MG, Hornstein MD. Is intracytoplasmic sperm injection safe? Fertil Steril 2003;80:851–9. 15. In’t Veld PA, van Opstal D, van den Berg C, van Ooijen M, Brandenburg H, Pijpers L, et al. Increased incidence of cytogenetic abnormalities in chorionic villus samples from pregnancies established by in vitro fertilization and embryo transfer (IVF-ET). Prenat Diagn 1995;15:975–80. 16. Munne S, Magli C, Adler A, Wright G, de Boer K, Mortimer D, et al. Treatment-related chromosome abnormalities in human embryos. Hum Reprod 1997;12:780–4.
ART and cytogenetic abnormalities
17. Martinez MC, Mendez C, Ferro J, Nicolas M, Serra V, Landeras J. Cytogenetic analysis of early nonviable pregnancies after assisted reproduction treatment. Fertil Steril 2010;93:289–92. 18. Bettio D, Venci A, Levi Setti PE. Chromosomal abnormalities in miscarriages after different assisted reproduction procedures. Placenta 2008;29(Suppl 8). 19. Shields LE, Serafini PC, Schenken RS, Moore CM. Chromosomal analysis of pregnancy losses in patients undergoing assisted reproduction. J Assist Reprod Genet 1992;9:57–60. 20. Rizk B, Doyle P, Tan SL, Rainsbury P, Betts J, Brinsden P, et al. Perinatal outcome and congenital malformations in in-vitro fertilization babies from the Bourn-Hallam group. Hum Reprod 1991;6:1259–64. 21. French In Vitro National (FIVNAT). Pregnancies and births resulting from in vitro fertilization: French national registry, analysis of data 1986 to 1990. Fertil Steril 1995;64:746–56. 22. Olivennes F, Kerbrat V, Rufat P, Blanchet V, Fanchin R, Frydman R. Follow-up of a cohort of 422 children aged 6 to 13 years conceived by in vitro fertilization. Fertil Steril 1997;67:284–9. 23. Tanbo T, Dale PO, Lunde O, Moe N, Abyholm T. Obstetric outcome in singleton pregnancies after assisted reproduction. Obstet Gynecol 1995;86:188–92. 24. Morin NC, Wirth FH, Johnson DH, Frank LM, Presburg HJ, Van de Water VL, et al. Congenital malformations and psychosocial development in children conceived by in vitro fertilization. J Pediatr 1989;115: 222–7. 25. Huang A, Adusumalli J, Patel S, Liem J, Williams III J, Pisarska MD. Prevalence of chromosomal mosaicism in pregnancies from couples with infertility. Fertil Steril 2009;91:2355–60.
Vol. 95, No. 2, February 2011