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doi:10.1111/jog.12403
J. Obstet. Gynaecol. Res. Vol. 40, No. 6: 1653–1660, June 2014
Validity for assisted hatching on pregnancy rate in assisted reproductive technology: Analysis based on results of Japan Assisted Reproductive Technology Registry System 2010 Takashi Nakasuji1, Hidekazu Saito1, Ryuichiro Araki2, Aritoshi Nakaza3, Akira Kuwahara4, Osamu Ishihara5, Minoru Irahara4, Toshiro Kubota6, Yasunori Yoshimura7 and Tetsuro Sakumoto3 1 Division of Reproductive Medicine, National Center for Child Health and Development, 6Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Systemic Organ Regulation, Graduate School, Tokyo Medical and Dental University, 7Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, 2 Community Health Science Center, Saitama Medical University, 5Department of Obstetrics and Gynecology, Saitama Medical University, Saitama, 3Alba Okinawa Clinic, Okinawa, and 4Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Tokushima, Japan
Abstract Aim: The aim of this study was to assess the efficacy of assisted hatching (AH) in assisted reproductive technology (ART) treatment. Material and Methods: In this retrospective observational study, the data of patients who were registered in the National ART Registry System of Japan between January and December 2010 were analyzed. The descriptive statistics and validity of AH in fresh embryo transfer (ET) and frozen–thawed ET were assessed by using multiple logistic regression analyses. Results: From a total of 105 450 single ET, 46 029 (43.7%) cycles underwent AH. A total of 9737 (21.3%) and 36 292 (60.9%) cycles underwent AH from 45 818 fresh single ET and 59 632 frozen–thawed single ET, respectively. In the fresh ET patients that underwent AH, the clinical pregnancy and live birth rate were significantly decreased in patients of all ages compared with that of the non-AH group. In the frozen–thawed ET patients, there was no significant difference in pregnancy and live birth rate between the AH group and the non-AH group. Conclusion: AH treatment was more frequently performed in frozen–thawed ET patients than in fresh ET patients, and in the blastocyst stage than in the early cleavage stage. A significantly decreased pregnancy and live birth rate was observed in the fresh ET patients who underwent AH. In the frozen–thawed ET patients who underwent AH, improvement in the clinical pregnancy and live birth rate was not observed. Further studies on the indication and application of AH in ART treatment are required. Key words: assisted hatching, clinical pregnancy rate, fresh embryo transfer, frozen–thawed embryo transfer, National Assisted Reproductive Technology Registry System.
Received: September 5 2013. Accepted: January 15 2014. Reprint request to: Dr Takashi Nakasuji, Division of Reproductive Medicine, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan. Email: [email protected]
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
1653
T. Nakasuji et al.
Introduction Assisted reproductive technology (ART) has been developed in the past 3 decades to support a significant number of infertile couples. The clinical pregnancy rate of ART treatment is approximately 20–30%.1 To improve the clinical pregnancy rate, various treatment options have been reported, including assisted hatching (AH).2,3 AH involves artificial thinning or making a small hole in the zona pellucida (ZP) in order to facilitate the hatching process with ART. An increased implantation rate following the mechanical opening of the ZP was first reported in 1990.4 Randomized controlled trials (RCT) showed that AH was related to increased clinical pregnancy rates.5–7 However, it is not recommended that AH be routinely performed in ART.2,3 AH may be clinically useful in patients with a poor prognosis for pregnancy, including those who have failed two or more times in in vitro fertilization (IVF) treatment cycles, those with poor embryo quality, and older women (≥38 years of age).2 AH was related to increased clinical pregnancy rates in women with previous repeated failure or frozen–thawed embryos.3 On the other hand, AH was unlikely to increase clinical pregnancy rates when performed in fresh embryos transferred to unselected, non-poor-prognosis or advancedaged women.3 A recent meta-analysis reported that AH was related to increased clinical pregnancy rates in women with previous repeated failure or fresh embryo transfer (ET), while this was not for the case for frozen ET.8 The efficacy of AH is still debated. In the present study, the efficacy of AH in improving pregnancy rate is analyzed and assessed in a large scale based on registered data from the Japan Society of Obstetrics and Gynecology (JSOG) of 2010.
mechanical, and acid Tyrodes, and treatment history, such as previous implantation failure, and embryo morphology, were unknown in our registry. The data regarding egg donations were also not included due to the JSOG regulations. Clinical pregnancies were defined as the detection of a gestational sac by ultrasound. The incomplete data were excluded from the multiple logistic regression analyses. The present study was approved by the registration and research subcommittee of the JSOG ethics committee, and all of the data analyzed in this study were provided by the JSOG. To compare maternal age with fertilization methods and duration of the culture with rate of AH performed, stratified analyses (the Mantel-extension test for trend and the Mantel–Haenszel test) were used. To correlate AH and possible factors that might affect embryo implantation with success in pregnancy and live birth, multiple logistic regression analyses were applied with forward variable selection. In fresh ET patients, variables for adjustments were as follows: use of AH, age, fertilization method, duration of embryo culture, ovarian stimulation procedure, and luteal support. In frozen–thawed ET patients, variables for adjustments were as follows: use of AH, age, duration of embryo culture, endometrial preparation, and luteal support. Analyses were performed in the following four subgroups: all ages and fresh ET, advanced maternal ages (≥35) and fresh ET, all ages and frozen–thawed ET, and advanced maternal ages and frozen–thawed ET. Thereby, crude and adjusted odds ratios (cOR and aOR), 95% confidence intervals (CI), and P-values of likelihood ratio test for each independent variable were estimated. All analyses were performed using IBM spss 21.0 for Windows and sas 9.1.3 SP4. A significant difference was defined as P < 0.05 in all analyses.
Methods
Results
A retrospective observational study was performed to examine the efficacy of AH in improving the clinical pregnancy and live birth rate in single ET. It has been mandatory for registered ART clinics to report their cycle-based clinical data via a web-based registry system since 2007, and AH was added to the registry system in 2010. Data from patients who were registered in the National ART Registry System of Japan between January and December 2010 were analyzed. Of 591 registered ART clinics, 587 (99.3%) clinics reported their cycle-based clinical data. The type of AH, such as laser,
In the present study, there were 105 450 cycles with single ET, and AH was performed in 46 029 of these. The mean ages of patients for assisted reproduction cycles with single ET, cycles with AH, and cycles without AH were 36.5 ± 4.4 (mean ± SD), 36.7 ± 4.4, and 36.3 ± 4.4 years, respectively. The number of cycles according to patient ages and different types of treatments are shown in Tables 1–3. There was a statistically significant and monotonic increase in the rate of AH performed with advanced maternal age across the strata, that is, IVF, intracytoplasmic sperm injection (ICSI), and frozen–thawed ET (P < 0.01,
1654
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
Assisted hatching in Japan
Table 1 Characteristics of AH with IVF Category
Variable
Total n
AH (–) n
AH (+) n (%)
Age (years)
≦34 35–39 ≧40 Early cleavage stage Blastocyst stage Natural CC CC+HMG HMG GnRH agonist GnRH antagonist None P hCG hCG + P E+P
6432 8005 5378 14435 5380 1448 2532 2869 494 6685 2978 644 7522 881 4635 4234
5654 6750 4253 12323 4334 1139 2457 2365 397 5633 2251 525 6512 811 3847 3436
778 (12.1) 1255 (15.7) 1125 (20.9) 2112 (14.6) 1046 (19.4) 309 (21.3) 75 (3.0) 504 (17.6) 97 (19.6) 1052 (15.7) 727 (24.4) 119 (18.5) 1010 (13.4) 70 (7.9) 788 (17.0) 798 (18.8)
Duration of culture Ovarian stimulation procedure
Luteal support
AH, assisted hatching; CC, clomiphene citrate; E, estrogen; GnRH, gonadotrophin-releasing hormone; hCG, human chorionic gonadotrophin; HMG, human menopausal gonadotrophin; IVF, in vitro fertilization; P, progesterone.
Table 2 Characteristics of AH with ICSI Category
Variable
Total n
AH (–) n
AH (+) n (%)
Age (years)
≦34 35–39 ≧40 Early cleavage stage Blastocyst stage Natural CC CC + HMG HMG GnRH agonist GnRH antagonist None P hCG hCG + P E+P
7722 10139 8142 18771 7232 1696 3112 3578 558 8315 5473 838 10011 584 4893 6526
6091 7655 5678 14689 4735 1232 2924 2708 357 6066 3895 658 8130 526 3726 4412
1631 (21.1) 2484 (24.5) 2464 (30.3) 4082 (21.7) 2497 (34.5) 464 (27.4) 188 (6.0) 870 (24.3) 201 (36.0) 2249 (27.0) 1578 (28.8) 180 (21.5) 1881 (18.8) 58 (9.9) 1167 (23.9) 2114 (32.4)
Duration of culture Ovarian stimulation procedure
Luteal support
AH, assisted hatching; CC, clomiphene citrate; E, estrogen; GnRH, gonadotrophin-releasing hormone; hCG, human chorionic gonadotrophin; HMG, human menopausal gonadotrophin; ICSI, intracytoplasmic sperm injection; P, progesterone.
Mantel-extension test for trend). There was a statistically significant and monotonic increase in the rate of AH performed corresponding to IVF, ICSI, and frozen– thawed ET across the strata, that is, age groups (≤34, 35–39, and ≥40 years) (P < 0.01, Mantel-extension test for trend). The rate of AH performed was higher in the blastocyst stage than in the early cleavage stage across the strata, that is, IVF, ICSI, and frozen–thawed ET (P < 0.01, Mantel–Haenszel test).
The odds ratios for clinical pregnancy with AH and other variables using the fresh ET procedure are shown in Tables 4 and 5. The odds ratios for live birth with AH and other variables using the fresh ET procedure are shown in Tables 6 and 7. Among the women of all ages who underwent the fresh ET procedure, there were 35 973 cycles, 7934 (22.1%) women became pregnant and 6047 were live birth. Among the women of advanced maternal age (≥35 years) who underwent the
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
1655
T. Nakasuji et al.
Table 3 Characteristics of AH with frozen–thawed embryo transfer Category
Variable
Total n
AH (–) n
AH (+) n (%)
Age (years)
≦34 35–39 ≧40 Early cleavage stage Blastocyst stage Natural ovulatory cycle HRT cycle None P hCG hCG + P E+P
20518 24970 14144 12554 47078 9175 5740 3294 15713 1620 5469 28892
8665 9692 4983 6660 16680 4590 2979 1708 7228 839 3105 8912
11853 (57.8) 15278 (61.2) 9161 (64.8) 5894 (46.9) 30398 (64.6) 4585 (50.0) 2761 (48.1) 1586 (48.1) 8485 (54.0) 781 (48.2) 2364 (43.2) 19980 (69.2)
Duration of culture Endometrial preparation Luteal support
AH, assisted hatching; E, estrogen; hCG, human chorionic gonadotrophin; HRT, hormone replacement therapy; P, progesterone.
Table 4 Predictors of clinical pregnancy in each variable with all ages and fresh embryo transfer Category
Variable
cOR (95%CI)
aOR (95%CI)†
AH
Not performed Performed
Referent 0.78 (0.73–0.83) 0.89 (0.88–0.89) Referent 0.85 (0.81–0.90) Referent 1.82 (1.72–1.92)
Referent 0.85 (0.79–0.91) 0.89 (0.89–0.90) Referent 0.89 (0.84–0.94) Referent 1.68 (1.59–1.78)
Age (by 1 year) Fertilization method Duration of embryo culture
IVF ICSI Early cleavage stage Blastocyst stage
P†
doi:10.1111/jog.12403
J. Obstet. Gynaecol. Res. Vol. 40, No. 6: 1653–1660, June 2014
Validity for assisted hatching on pregnancy rate in assisted reproductive technology: Analysis based on results of Japan Assisted Reproductive Technology Registry System 2010 Takashi Nakasuji1, Hidekazu Saito1, Ryuichiro Araki2, Aritoshi Nakaza3, Akira Kuwahara4, Osamu Ishihara5, Minoru Irahara4, Toshiro Kubota6, Yasunori Yoshimura7 and Tetsuro Sakumoto3 1 Division of Reproductive Medicine, National Center for Child Health and Development, 6Comprehensive Reproductive Medicine, Regulation of Internal Environment and Reproduction, Systemic Organ Regulation, Graduate School, Tokyo Medical and Dental University, 7Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, 2 Community Health Science Center, Saitama Medical University, 5Department of Obstetrics and Gynecology, Saitama Medical University, Saitama, 3Alba Okinawa Clinic, Okinawa, and 4Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Tokushima, Japan
Abstract Aim: The aim of this study was to assess the efficacy of assisted hatching (AH) in assisted reproductive technology (ART) treatment. Material and Methods: In this retrospective observational study, the data of patients who were registered in the National ART Registry System of Japan between January and December 2010 were analyzed. The descriptive statistics and validity of AH in fresh embryo transfer (ET) and frozen–thawed ET were assessed by using multiple logistic regression analyses. Results: From a total of 105 450 single ET, 46 029 (43.7%) cycles underwent AH. A total of 9737 (21.3%) and 36 292 (60.9%) cycles underwent AH from 45 818 fresh single ET and 59 632 frozen–thawed single ET, respectively. In the fresh ET patients that underwent AH, the clinical pregnancy and live birth rate were significantly decreased in patients of all ages compared with that of the non-AH group. In the frozen–thawed ET patients, there was no significant difference in pregnancy and live birth rate between the AH group and the non-AH group. Conclusion: AH treatment was more frequently performed in frozen–thawed ET patients than in fresh ET patients, and in the blastocyst stage than in the early cleavage stage. A significantly decreased pregnancy and live birth rate was observed in the fresh ET patients who underwent AH. In the frozen–thawed ET patients who underwent AH, improvement in the clinical pregnancy and live birth rate was not observed. Further studies on the indication and application of AH in ART treatment are required. Key words: assisted hatching, clinical pregnancy rate, fresh embryo transfer, frozen–thawed embryo transfer, National Assisted Reproductive Technology Registry System.
Received: September 5 2013. Accepted: January 15 2014. Reprint request to: Dr Takashi Nakasuji, Division of Reproductive Medicine, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan. Email: [email protected]
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
1653
T. Nakasuji et al.
Introduction Assisted reproductive technology (ART) has been developed in the past 3 decades to support a significant number of infertile couples. The clinical pregnancy rate of ART treatment is approximately 20–30%.1 To improve the clinical pregnancy rate, various treatment options have been reported, including assisted hatching (AH).2,3 AH involves artificial thinning or making a small hole in the zona pellucida (ZP) in order to facilitate the hatching process with ART. An increased implantation rate following the mechanical opening of the ZP was first reported in 1990.4 Randomized controlled trials (RCT) showed that AH was related to increased clinical pregnancy rates.5–7 However, it is not recommended that AH be routinely performed in ART.2,3 AH may be clinically useful in patients with a poor prognosis for pregnancy, including those who have failed two or more times in in vitro fertilization (IVF) treatment cycles, those with poor embryo quality, and older women (≥38 years of age).2 AH was related to increased clinical pregnancy rates in women with previous repeated failure or frozen–thawed embryos.3 On the other hand, AH was unlikely to increase clinical pregnancy rates when performed in fresh embryos transferred to unselected, non-poor-prognosis or advancedaged women.3 A recent meta-analysis reported that AH was related to increased clinical pregnancy rates in women with previous repeated failure or fresh embryo transfer (ET), while this was not for the case for frozen ET.8 The efficacy of AH is still debated. In the present study, the efficacy of AH in improving pregnancy rate is analyzed and assessed in a large scale based on registered data from the Japan Society of Obstetrics and Gynecology (JSOG) of 2010.
mechanical, and acid Tyrodes, and treatment history, such as previous implantation failure, and embryo morphology, were unknown in our registry. The data regarding egg donations were also not included due to the JSOG regulations. Clinical pregnancies were defined as the detection of a gestational sac by ultrasound. The incomplete data were excluded from the multiple logistic regression analyses. The present study was approved by the registration and research subcommittee of the JSOG ethics committee, and all of the data analyzed in this study were provided by the JSOG. To compare maternal age with fertilization methods and duration of the culture with rate of AH performed, stratified analyses (the Mantel-extension test for trend and the Mantel–Haenszel test) were used. To correlate AH and possible factors that might affect embryo implantation with success in pregnancy and live birth, multiple logistic regression analyses were applied with forward variable selection. In fresh ET patients, variables for adjustments were as follows: use of AH, age, fertilization method, duration of embryo culture, ovarian stimulation procedure, and luteal support. In frozen–thawed ET patients, variables for adjustments were as follows: use of AH, age, duration of embryo culture, endometrial preparation, and luteal support. Analyses were performed in the following four subgroups: all ages and fresh ET, advanced maternal ages (≥35) and fresh ET, all ages and frozen–thawed ET, and advanced maternal ages and frozen–thawed ET. Thereby, crude and adjusted odds ratios (cOR and aOR), 95% confidence intervals (CI), and P-values of likelihood ratio test for each independent variable were estimated. All analyses were performed using IBM spss 21.0 for Windows and sas 9.1.3 SP4. A significant difference was defined as P < 0.05 in all analyses.
Methods
Results
A retrospective observational study was performed to examine the efficacy of AH in improving the clinical pregnancy and live birth rate in single ET. It has been mandatory for registered ART clinics to report their cycle-based clinical data via a web-based registry system since 2007, and AH was added to the registry system in 2010. Data from patients who were registered in the National ART Registry System of Japan between January and December 2010 were analyzed. Of 591 registered ART clinics, 587 (99.3%) clinics reported their cycle-based clinical data. The type of AH, such as laser,
In the present study, there were 105 450 cycles with single ET, and AH was performed in 46 029 of these. The mean ages of patients for assisted reproduction cycles with single ET, cycles with AH, and cycles without AH were 36.5 ± 4.4 (mean ± SD), 36.7 ± 4.4, and 36.3 ± 4.4 years, respectively. The number of cycles according to patient ages and different types of treatments are shown in Tables 1–3. There was a statistically significant and monotonic increase in the rate of AH performed with advanced maternal age across the strata, that is, IVF, intracytoplasmic sperm injection (ICSI), and frozen–thawed ET (P < 0.01,
1654
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
Assisted hatching in Japan
Table 1 Characteristics of AH with IVF Category
Variable
Total n
AH (–) n
AH (+) n (%)
Age (years)
≦34 35–39 ≧40 Early cleavage stage Blastocyst stage Natural CC CC+HMG HMG GnRH agonist GnRH antagonist None P hCG hCG + P E+P
6432 8005 5378 14435 5380 1448 2532 2869 494 6685 2978 644 7522 881 4635 4234
5654 6750 4253 12323 4334 1139 2457 2365 397 5633 2251 525 6512 811 3847 3436
778 (12.1) 1255 (15.7) 1125 (20.9) 2112 (14.6) 1046 (19.4) 309 (21.3) 75 (3.0) 504 (17.6) 97 (19.6) 1052 (15.7) 727 (24.4) 119 (18.5) 1010 (13.4) 70 (7.9) 788 (17.0) 798 (18.8)
Duration of culture Ovarian stimulation procedure
Luteal support
AH, assisted hatching; CC, clomiphene citrate; E, estrogen; GnRH, gonadotrophin-releasing hormone; hCG, human chorionic gonadotrophin; HMG, human menopausal gonadotrophin; IVF, in vitro fertilization; P, progesterone.
Table 2 Characteristics of AH with ICSI Category
Variable
Total n
AH (–) n
AH (+) n (%)
Age (years)
≦34 35–39 ≧40 Early cleavage stage Blastocyst stage Natural CC CC + HMG HMG GnRH agonist GnRH antagonist None P hCG hCG + P E+P
7722 10139 8142 18771 7232 1696 3112 3578 558 8315 5473 838 10011 584 4893 6526
6091 7655 5678 14689 4735 1232 2924 2708 357 6066 3895 658 8130 526 3726 4412
1631 (21.1) 2484 (24.5) 2464 (30.3) 4082 (21.7) 2497 (34.5) 464 (27.4) 188 (6.0) 870 (24.3) 201 (36.0) 2249 (27.0) 1578 (28.8) 180 (21.5) 1881 (18.8) 58 (9.9) 1167 (23.9) 2114 (32.4)
Duration of culture Ovarian stimulation procedure
Luteal support
AH, assisted hatching; CC, clomiphene citrate; E, estrogen; GnRH, gonadotrophin-releasing hormone; hCG, human chorionic gonadotrophin; HMG, human menopausal gonadotrophin; ICSI, intracytoplasmic sperm injection; P, progesterone.
Mantel-extension test for trend). There was a statistically significant and monotonic increase in the rate of AH performed corresponding to IVF, ICSI, and frozen– thawed ET across the strata, that is, age groups (≤34, 35–39, and ≥40 years) (P < 0.01, Mantel-extension test for trend). The rate of AH performed was higher in the blastocyst stage than in the early cleavage stage across the strata, that is, IVF, ICSI, and frozen–thawed ET (P < 0.01, Mantel–Haenszel test).
The odds ratios for clinical pregnancy with AH and other variables using the fresh ET procedure are shown in Tables 4 and 5. The odds ratios for live birth with AH and other variables using the fresh ET procedure are shown in Tables 6 and 7. Among the women of all ages who underwent the fresh ET procedure, there were 35 973 cycles, 7934 (22.1%) women became pregnant and 6047 were live birth. Among the women of advanced maternal age (≥35 years) who underwent the
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
1655
T. Nakasuji et al.
Table 3 Characteristics of AH with frozen–thawed embryo transfer Category
Variable
Total n
AH (–) n
AH (+) n (%)
Age (years)
≦34 35–39 ≧40 Early cleavage stage Blastocyst stage Natural ovulatory cycle HRT cycle None P hCG hCG + P E+P
20518 24970 14144 12554 47078 9175 5740 3294 15713 1620 5469 28892
8665 9692 4983 6660 16680 4590 2979 1708 7228 839 3105 8912
11853 (57.8) 15278 (61.2) 9161 (64.8) 5894 (46.9) 30398 (64.6) 4585 (50.0) 2761 (48.1) 1586 (48.1) 8485 (54.0) 781 (48.2) 2364 (43.2) 19980 (69.2)
Duration of culture Endometrial preparation Luteal support
AH, assisted hatching; E, estrogen; hCG, human chorionic gonadotrophin; HRT, hormone replacement therapy; P, progesterone.
Table 4 Predictors of clinical pregnancy in each variable with all ages and fresh embryo transfer Category
Variable
cOR (95%CI)
aOR (95%CI)†
AH
Not performed Performed
Referent 0.78 (0.73–0.83) 0.89 (0.88–0.89) Referent 0.85 (0.81–0.90) Referent 1.82 (1.72–1.92)
Referent 0.85 (0.79–0.91) 0.89 (0.89–0.90) Referent 0.89 (0.84–0.94) Referent 1.68 (1.59–1.78)
Age (by 1 year) Fertilization method Duration of embryo culture
IVF ICSI Early cleavage stage Blastocyst stage
P†
