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Online ISSN (İngilizce)
1305-3124

Basılı ISSN (Türkçe)
1300-5251

Online ISSN (Türkçe)
1305-3132

Kuruluş
1993

Editör
Cihat Şen

Yardımcı Editörler
Murat Yayla, Oluş Api

How can we prevent iatrogenic twıns in art

Ramon Aurell

Künye

How can we prevent iatrogenic twıns in art. Perinatoloji Dergisi 2005;13(2):s67-77

Yazar Bilgileri

Ramon Aurell

  1. Reproductive Medicine Unit. Department of Obstetrics & Gynaecology. Institut Universitari Dexeus- Barcelona ES
Yazışma Adresi

Ramon Aurell, Reproductive Medicine Unit. Department of Obstetrics & Gynaecology. Institut Universitari Dexeus- Barcelona ES, ramaur@dexeus.com

Yayın Geçmişi

Yayınlanma Tarihi: 01 Nisan 2005

Çıkar Çakışması

Çıkar çakışması bulunmadığı belirtilmiştir.

Giriş

Iatrogenic Multiple Pregnancies and Ovulation InductionThe number of Multiple Pregnancies in southern Europe was reaching epidemic proportions in the late 1990swith the relevant consequences for the children, parents and the community in general(1,2).Ovulation induction(OI) accounts for approximately 40% of the total of the high order multiple pregnancies(2).In medical and socialterms this pregnancies can have negative consequences. Recent studies have mentioned that the risk of an infertile couple from having a high order MP from ovulation induction or Insemination is greater than of having IVF(3,4).
It seems then obvious the need for regulations and guidelines to avoid the increasing number of high order MPsecondary to OI.
OI without ART is estimated to be responsible for 20% of twin birth and 30% of triplet and high-order MP. In Britain, OI alone is responsible for 67% of quadruplet and higher-order births(6). Recent work by us(5)and others(7)has suggested that certain factors are associated with high order MP, triplets ormore, after gonadotrophin stimulation and if conservative limits for follicular development and oestradiol levelsare applied the number of high order MP secondary to OI will be significantly reduced. In our previous study(5)we analyzed retrospectively a large series of 1878 consecutive pregnancies fromgonadotrophins stimulated cycles. We developed a three-variable model to identify patients at high risk forhigh order MP in OI cycles. We found the correlation between high order MP with increasing total number of follicles, oestradiol level >862pg/ml and age > or = 32 years(5)Strategies to prevent MP in OI and Insemination (IUI)1. Alternative to gonadotrophin treatment
2. Strategies in OI
3. Alternatives to cancelled cycles
4. Cancelled cycles
5. Embryo reduction
1. Several alternatives with good results are used to reduce the number of MP from OI: Clomiphene Citrate(Imani, 1998, 1999, 2000; Eijkemans, 2003; Dickey 2002, 2004; Matorras, 2003.), Aromatase inhibitors(Mitwally, 2003; Fatemi, 2003), Diet and Exercise (Kiddy, 1998; Norman, 2004), Ovarian drilling (Farquhar,2002; Bayram, 2004), or IVF.
2. The known strategies to avoid MP in OI, are : individualised treatment protocols, according to patients age,indication for treatment, number of antral follicles, basal FSH levels and BMI. Use of soft stimulation protocols, with small dose of gonadotrophins or low step-up protocols, and the use of careful monitoring ofovarian response with transvaginal USS and serum oestradiol levels.
3. Several alternatives are been used to reduce the number of cancelled cycles. Triggering of ovulation byGnRH agonist: Emperaire, 1991; Check, 1993; Balasch, 1994. Convert hiperstimulated cycles to IVF; Nisker,1994; Bergh, 1998; Antman, 2002; Monzo, 2004. Puncture of supernumerary follicles: Belaisch, 1998; DeGeyter, 1996, 1998; Albano, 2001.Criteria for Cancellation:İn our study, between June 2001 and December 2002, we looked at 849 consecu-tive patients receiving gonadotropin ovarian stimulation or OI without IVF for a total of 1542 treatment cycles.Patients were administered highly purifies FSH (Neofertinorm: Serono) or recombinat FSH (Gonal-F: Serono).The regimen was chronic low-dose step-up protocol, with an starting dose of 75IU in >85% of women, 37.5IUin previous high responders and 150IU in women >40 years of age. Ovarian response was monitored by serialvaginal USS follicular measurement and serum E2 detreminations. Couples were counselled about the risk of MP according to the prediction model established in our previousstudy (table 1, Ref 5) Results are summarized in Figures 1 and 2 and in Table 2. The main objective of any infertility therapy is to achieve a healthy single child: MP jeopardize that objectiveand high-order MP should be considered as an adverse outcome. As many as 2/3 of Iatrogenic MP, mainlyinvolving triplets and more, may be attributable to OI drugs without IVF . There has been major control of IVFMP than with OI, therefore, identification of predictors of MP during OI cycles is clearly necessary. In the present study we tested prospectively a three-variable prediction model for high-order MP.Using this model is possible to maintain low risk high-order MP with good pregnancy rates. As many as 77.4%patients met the low-risk definition probably due to the conservative step-up treatment approach that we usedin this study. Prevention of MP in IVF Introduction During the past decade, in some countries, legislative guidelines targeted at limiting the number of embryostransferred have been promulgated in an effort to reduce the incidence of multiple gestations(8).By limiting thenumber of embryos transferred per stimulated IVF cycles, the incidence of MP is reduced. However , when following this policy, a number of considerations are necessary in order to maintain an acceptable pregnancyrate: number of embryos available for transfer, embryo quality and womens, age (9).Instituto Universitario Dexeus Multiple Pregnancy Score; MPSIn our unit we have been working towards reducing MP since late 90,s. We believe in Single ET (SET) and inSelective Single ET (sSET) trying to reduce the total number of MP and births. In Fig 2 is evident the increasein MP in Spain from the 90,s. We worked towards the creation of a Embryo Transfer Score system trying to reduce the number of MP. Forthe last four years since the creation of the score we managed to reduce the incidence of MP without reducingsubstantially the pregnancy rates.MATERIALS AND METHODS. CREATION OF MPS.
Retrospective analysis
A retrospective study was carried out on 377 cycles from our IVF/ICSI program between March andSeptember 1999. As our main goal was to reduce triplets, only those patients with whom three embryos weretransferred (day two post-puncture) were included in the study. A total of 227 cycles were analyzed, amongwhich 120 resulted in pregnancy (64 singletons, 39 twins and 17 triplets) and 107 did not result in pregnancy.The following parameters were analyzed: patient age, cause of infertility, number of cycle attempts, total number of embryos (number of available embryos at the moment of transfer) and total number of good qualityembryos (number of good quality embryos available for transfer). A good quality embryo on day two wasdefined as one which, 48h after insemination or ICSI showed four regular blastomeres and less than 20% cytoplasmic fragmentation (Boiso et al., 2002).
No-pregnancy, singleton, twin and triplet cycles were compared according to the above parameters. Statisticalanalysis was performed with the SPSS® 10.0 software program for Windows ® (SPSS Inc., Chicago, IL,USA). Chi-square test, Fisher’s test, Student’s t test and analysis of variance were used to compare qualitativeand quantitative variables. A further comparison was then made of singleton versus triplet pregnancies, andvariables that were significantly associated with high-order multiple pregnancy were retained for testing in amultivariate logistic regression model. Receiver operating characteristic (ROC) curves were used to determinethe cut-off point that best discriminated between high-order multiple pregnancy (* 3 gestational sacs) and single gestation (1 gestational sac). Significance was set at p <0.05.Prospective studyA prospective study was conducted with patients enrolled in our IVF/IVF-ICSI program between January andSeptember 2002. Only those women who underwent embryo transfer on day two after oocyte retrieval and hadthree or more embryos available at the moment of transfer were included in the study. The number of embryosto be transferred was decided upon according to the MPS and patients who agreed with the proposed number ofembryos (MPS-accepted group; n=301) were compared with those who requested more (MPS-not acceptedgroup; n=92), the latter acting as the control group (Table IV). The sample was then stratified according to thenumber of embryos the MPS had recommended transferring (one, two or three), and patients accepting the recommendation were compared with those who did not (Table V). For example, if the MPS recommendedtransfer of one embryo, either one (1ET) or two embryos (2ET) were transferred, depending on whether thepatient accepted the MPS or not (MPS=1, 1ET vs. 2ET). Clinical pregnancy rates and multiple pregnancy rates were compared in all the groups using the chi-square or Fisher’s test, where appropriate. Pregnancy was diagnosed by positive urine and/or blood tests (Beta hCG) and the subsequent visualization of at least one intrauterine gestational sac by transvaginal ultrasonography at 6 weeks gestation. The order of the multiple pregnancy was classified according to the highest number of gestational sacs observed by ultrasound imaging, including pregnancy sacs that did not contain an embryonic pole. Assessmentof the outcome of pregnancy was not considered for the specific purpose of this study.Results

Results of the retrospective analysis:

Table I shows the comparison between no-pregnancy and single, twin and triplet pregnancies. Univariate analysis found no significant differences between the four groups with respect to cause of infertility or numberof cycle attempts. There were, however, significant differences in terms of age, total number of embryos available for transfer and number of good quality embryos. The same differences were found when comparing only single and triplet pregnancies. When the three significant variables were entered simultaneously into the logistic regression model, only two of them remainedsignificant: age and number of good quality embryos. Of these, the number of good quality embryos was themost significant. Analysis of ROC curves produced the following cut-off values: two good quality embryos(Sensitivity 81.3, with 95% CI=69.5-89.9; Specificity 64.7, with 95% CI=38.4-85.7, area under the ROC curve0.785); 34 years of age (Sensitivity 50.0, with 95% CI=37.2-62.8; Specificity 76.5, with 95% CI=50.1-93.0,area under the ROC curve 0.665). Table II shows that the rate of triplet pregnancies increases along with thenumber of good quality embryos available.

Multiple pregnancy score:The MPS was developed on the basis of the two cut-off values identified above: age=34 years and two goodquality embryos. As Table II shows, the rate of triplet pregnancies increased notably when more than two goodquality embryos were available. Therefore, it was decided to award one point for each good quality embryo(Table III). In terms of age, one point was awarded for the cut-off value of 34 years, but the overall scoringrange also took into account that the risk of multiple pregnancy has been shown to be higher for women under 30 and lower for those over 40. Consequently, the final scoring system was as shown in Table III. We then proposed the following criteria: one embryo would be transferred when the final MPS was 5 or 6, two embryoswhen the MPS was 3 or 4 and 3 embryos when it was less than 3.Results of the prospective study
Of the 393 women with at least three available embryos at the moment of transfer, 301 accepted transfer of thenumber of embryos recommended by the MPS (76.6%, MPS-accepted group) and 92 requested more embryos(23.4%, MPS-not accepted group). The overall clinical pregnancy rate per embryo transfer was significantly different: 50.5% in the MPS-acceptedgroup (152 pregnancies / 301 transfers) vs. 67.4% in the MPS-not accepted group (62 pregnancies / 92 transfers) (p<0.01). However, the overall multiple pregnancy rate was significantly lower in the MPS-acceptedgroup (34.9% vs. 53.2% in the MPS not-accepted group; p<0.05) (Table IV). The number of embryos proposed by the MPS compared with the number actually transferred is shown inTable V. The MPS recommended transfer of one embryo (MPS 1) in 29.3 % of women (115/393); 45 accepted(MPS 1-1ET) and 70 requested two embryos (MPS 1-2ET). In 39.4% (155/393) of women, the MPS indicatedtransfer of two embryos (MPS 2); 139 accepted (MPS 2-2ET) and 16 requested three embryos (MPS 2-3ET).Finally, the MPS recommended transfer of three embryos (MPS 3) in 31.3 % (123/393) of women; 117 accepted (MPS 3-3ET) and 6 requested four embryos (MPS 3-4ET).
As seen in Table VI, there was a significant difference between the MPS 1-1ET and MPS 1- 2ET groups interms of the clinical pregnancy rate (42.2% and 68.6%, respectively) (p<0.01). However, there were no significant differences in either the MPS 2 (MPS 2-2ET, 59%; MPS 2-3ET, 68.8%) or MPS 3 (MPS 3-3ET,43.6%; MPS 3-4ET, 50%) groups, although the difference in the size of their respective sub-groups makes statistical comparison impossible. Nevertheless, the overall multiple pregnancy rate was always higher whenmore embryos than recommended by the MPS were transferred. For the MPS 1 group transfer of two embryosled to 54.2% of twin pregnancies, for the MPS 2 group transfer of three embryos led to 18.2% of triplets, andthis figure rose to 33.3% when four embryos were transferred in the MPS 3 group.DıscussıondThe risks of multiple gestation are well recognized and there is general agreement among the medical community that multiple pregnancy needs to be reduced (Land and Evers, 2003). However, despite variousguidelines and recommendations (ASRM,1999; ESHRE, 2001) multiple pregnancy rates have continued to riseover the last twenty years along with the increasingly widespread use of ART (Tur et al., 2001). Studies have shown that no more than two embryos should be transferred in young women with good qualityembryos (Dean et al., 2000). More recently, some authors (Vilska et al., 2001; De Neubourg et al., 2002) havesuggested that in the first attempt only one embryo should be transferred in such circumstances. However, theprognosis is not always so favourable, and rather than limiting the number of embryos transferred across allpatients, we believe it is better practice to decide selectively, according to individual characteristics. Several authors have analyzed risk factors for multiple pregnancy and the following have been identified:young age of women (Svendsen et al., 1996), embryo quality (Basil et al., 1997), both these factors (Minaretziset al., 1998), and number of embryos available for transfer (Engmann et al., 2001) - when several embryosdevelop, there is an increased likelihood that good quality embryos can be selected for replacement. Templetonand Morris (Templeton and Morris, 1998) found that older age, tubal infertility, longer duration of infertilityand a higher number of previous attempts were all associated with a significant decrease in multiple pregnancy,and, furthermore, the number of eggs fertilized and the number of embryos available for transfer were important factors in determining outcome. When more than four embryos were fertilized and available, transferof only two embryos did not decrease the likelihood of pregnancy, but it did reduce the chance of multiplepregnancy. Our retrospective study found the number of good quality embryos and age of women to be the most importantparameters related to the multiple pregnancy rate, whereas the total number of embryos available, number ofprevious cycle attempts and cause of infertility bore no relationship. Thus, the quality of the embryo transferredin a given cycle is the factor that most influences outcome. Other studies (Devreker et al., 1999) have shownbetter embryo quality for patients with more than five available embryos, regardless of maternal age. Ourresults suggest, however, that age also has an influence, with the multiple pregnancy rate being lower in olderwomen. Moreover, these women tend to have fewer available embryos and show a higher rate of chromosomalabnormalities. A correlation has been reported between maternal age and chromosomal abnormalities (Munne et al., 2002), and a relationship between morphological criteria and the ability of an embryo to develop to the blastocyst stage with chromosomal abnormalities (Sandalinas et al., 2001). These studies showthat a morphologically normal embryo may have chromosomal abnormalities, and since the implantation ratecan be lower in such cases, the transfer of more embryos may well be justified. Most authors recommend that transfer be carried out according to factors associated with good prognosis (age,cycle number, embryo quality etc.). However, our aim was to develop a standardized procedure (MPS) thattook into account the two factors identified in the multivariate study (age and number of good quality embryoson the day of transfer). By assigning different cut-off values the MPS enables a decision to be made regardingthe number of embryos to be transferred according to the specific characteristics of each cycle. The overall results of the prospective study show that 76.6% (301/393) of women accepted transfer of the number of embryos recommended by the MPS. However, while a majority of those with recommended transferof two (89.7%,139/155) or three (95.1%,117/123) embryos accepted this proposal, only 39% (45/115) ofwomen with recommended transfer of one embryo did so. Thus, couples generally accepted the risk of multiplepregnancy, particularly twins. In a survey of women who had had twins, either spontaneously or after IVF/ICSItechniques (Pinborg et al., 2003), only 17-24% said they would accept single embryo transfer; the possibility offree treatment and having had complications associated with twin pregnancy were factors related to acceptance.In Spain, eSET is still rarely used. ESHRE data from 1999 (Nygren and Andersen, 2002) show that only 8.6%of embryo transfers involved a single embryo (although it is not specified in the data, it is safe to assume thatthis figure refers predominantly to non-eSET). This contrasts sharply with the same data for Scandinaviancountries, the figure for Finland being 21.6%.
Although use of the MPS enabled us to reduce the rate of triplets to 2% (in 1999 the figure was 9.8% - unpublished data for our centre), there was no significant change in the rate of twin pregnancies (32.9% in the present study compared with 33.2% in 1999). However, overall results show that when the number of embryos transferred was greater than that recommended by the MPS, the resulting increase in the pregnancy rate (67.4% vs. 50.5% in MPS-accepted) was accompanied by a higher multiple pregnancyrate (4.8% of triplets and 48.4% of twins). Similar results were found for the MPS 1 group, the one most appropriate for evaluation because of the comparable number of cycles in the 1ET vs. 2ET subgroups.However, as was pointed out above, a similar comparison cannot be made for the MPS 2 and MPS 3 groups,since the relative number of cycles in each of their subgroups makes them impossible to compare statistically;the large majority of women in both groups accepted the MPS recommendation.
Most comparative studies of eSET vs. eDET have shown a higher pregnancy rate for the transfer of twoembryos, although the difference is not significant (Martikainen et al., 2001; Vilska et al., 2001; Gerris et al.,1999; Gerris et al., 2002). In contrast, we did achieve a significantly higher pregnancy rate when transferringtwo embryos, although this was accompanied by an unacceptably high twin pregnancy rate (54.2%). However,given that the pregnancy rate after eSET (42.2%) was more than acceptable, the increased risk of multiple pregnancy associated with the transfer of two embryos seems an unacceptable price to pay. In order to evaluatethese outcomes further, we would need to consider the cumulative clinical pregnancy rate after the transfer offrozen-thawed embryos (Martikainen et al., 2001; Tiitinen et al., 2001), as well as the cumulative live birth rateper couple (Ozturk et al., 2001). Although many authors (Engmann et al., 2001; Templeton and Morris, 1998) argue that the number of attemptsis a factor to take into account when deciding how many embryos to transfer, our results, in accordance withthose of Basil et al. (Basil et al., 1997), suggest that this is not an important variable. Nevertheless, the number of attempts may be a factor leading couples to request transfer of more embryos. As our centre is private, it isthe couples themselves who bear the cost of IVF cycles and this fact, combined with their desire to achievepregnancy, may be decisive. Indeed, IVF centres also want to achieve high pregnancy rates and the couples,whose priority is to achieve pregnancy, are usually willing to accept the risks of multiple pregnancy (Gleicheret al., 1995). Therefore, extensive counselling should be available regarding ongoing pregnancy rates and thepotential consequences for both mother and child of multiple pregnancies, not only those of a higher order butalso twins. In our opinion, the number of embryos to be transferred should be decided jointly with the coupleafter they have been fully informed of the risk involved, the aim being to achieve the greatest likelihood ofpregnancy and the lowest risk of multiple gestation. In our view, a strict policy aimed at limiting the number of embryos to be transferred (for example, no more than two in all cases) would excessively reduce the pregnancy rate. Thus, the purpose of the MPS is toachieve a similar pregnancy rate when transferring one, two or three embryos while avoiding - as much as possible - triplet pregnancies and keeping the number of twins to an acceptable minimum.Conclusion These preliminary results on the use of the MPS are a first step towards reducing multiple pregnancy rates, especially for triplet pregnancies. Although this scoring system can help to decide how manyembryos to transfer in order to minimize multiple pregnancy, a twin pregnancy rate of 32.9% is still unacceptably high, and the MPS will need to be improved to reduce it.
Anahtar Kelimeler

Kaynaklar

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Dosya / Açıklama
Figure 1
Observed HOMPs in 1.542 ovulation induction cycles
Figure 2
.Predicetd HOMPs with cancellation of cycles at high risk of HOMP.
Figure 3.
MP and Births in Spain, 1980-2002.
Figure 4.
MP in our institution from 1998-2003. We can see the evident decrease in MP, twins and triplets in our institu-tion since the implementation of the MPS in 2001.
Tablo 1
Observed numbers of cycles with low-order and high - order pregnancy and predicted probability of high-order pregnancy according to multivariate ordinal logistic regression analysis.a
Tablo 2
Pregnancy rates and incidence of HoMP according to the use or not af a prediction model for HOMP
Tablo 1
Comparison of study variables according to: 1) cycle results; and 2) single vs. triplet pregnancies
Tablo 2
IVF Single, twin and triplet rates after transfer of three embryos, according to the number of good quality embryos available for transfer
Tablo 3
MPS: Score given according to the number of good quality embryos and patient’s age
Tablo 4
Clinical pregnancy and multiple pregnancy rates: comparison between MPS-accepted group and MPS-not accepted group
Tablo 5
Study variables comparing MPS-accepted and not-accepted groups with respect to MPS recommendation
Tablo 6
Clinical pregnancy rates and multiple pregnancy rates: comparison between MPS-accepted group and MPS-not accepted group, stratified by MPS