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Featured researches published by K.G. Nygren.


Human Reproduction | 2008

Assisted reproductive technology in Europe, 2004: results generated from European registers by ESHRE

A. Nyboe Andersen; V. Goossens; A.P. Ferraretti; Siladitya Bhattacharya; R. Felberbaum; J. de Mouzon; K.G. Nygren

BACKGROUND European results of assisted reproductive techniques from treatments initiated during 2004 are presented in this eighth report. METHODS Data were mainly collected from existing national registers. From 29 countries, 785 clinics reported 367,066 treatment cycles including: IVF (114,672), ICSI (167,192), frozen embryo replacement (FER, 71,997), egg donation (ED, 10 334), preimplantation genetic diagnosis/screening (PGD/PGS, 2701) and in vitro maturation (IVM, 170). Overall, this represents only a marginal increase since 2003, due to a huge reduction in treatments in Germany. European data on intrauterine insemination using husband/partners semen (IUI-H) and donor semen (IUI-D) were reported from 20 countries. A total of 115,980 cycles (IUI-H, 98,388; IUI-D, 17,592) were included. RESULTS In 14 countries where all clinics reported to the IVF register, a total of 248,937 ART cycles were performed in a population of 261.6 million, corresponding to 1095 cycles per million inhabitants. For IVF, the clinical pregnancy rates per aspiration and per transfer were 26.6% and 30.1%, respectively. For ICSI, the corresponding rates were 27.1% and 29.8%. After IUI-H, the clinical pregnancy rate was 12.6% in women below 40. After IVF and ICSI, the distribution of transfer of 1, 2, 3 and 4 or more embryos was 19.2%, 55.3%, 22.1% and 3.3%, respectively. Compared with 2003, fewer embryos were transferred, but huge differences still existed between countries. The distribution of singleton, twin and triplet deliveries after IVF and ICSI combined was 77.2%, 21.7% and 1.0%, respectively. This gives a total multiple delivery rate of 22.7% compared with 23.1% in 2003 and 24.5% in 2002. After IUI-H in women below 40 years of age, 11.9% were twin and 1.3% triplet gestations. CONCLUSIONS Compared with earlier years, the reported number of ART cycles in Europe increased and the pregnancy rates increased marginally, even though fewer embryos were transferred and the multiple delivery rates were reduced.


Human Reproduction | 2009

Assisted reproductive technology and intrauterine inseminations in Europe, 2005: results generated from European registers by ESHRE ESHRE. The European IVF Monitoring Programme (EIM), for the European Society of Human Reproduction and Embryology (ESHRE)

A. Nyboe Andersen; V. Goossens; Siladitya Bhattacharya; A.P. Ferraretti; M. Kupka; J. de Mouzon; K.G. Nygren

BACKGROUND Results of assisted reproductive techniques from treatments initiated in Europe during 2005 are presented in this ninth report. Data were mainly collected from existing national registers. METHODS From 30 countries, 923 clinics reported 418 111 treatment cycles including: IVF (118 074), ICSI (203 329), frozen embryo replacement (79 140), oocyte donation (ED, 11 475), preimplantation genetic diagnosis/screening (5846) and in vitro maturation (247). Overall, this represents a 13.6% increase since 2004, partly due to inclusion of 28 417 cycles from Turkey. European data on intrauterine insemination using husband/partners semen (IUI-H) and donor semen (IUI-D) were reported from 21 countries and included 128 908 IUI-H and 20 568 IUI-D cycles. RESULTS In 16 countries where all clinics reported to the IVF register, 1115 cycles were performed per million inhabitants. For IVF, the clinical pregnancy rates per aspiration and per transfer were 26.9% and 30.3%, respectively. For ICSI, the corresponding rates were 28.5% and 30.9%. After IUI-H, the clinical pregnancy rate was 12.6% per insemination in women <40. After IVF and ICSI, the distribution of transfer of one, two, three and four or more embryos was 20.0%, 56.1%, 21.5% and 2.3%, respectively. Huge differences exist between countries. The distribution of singleton, twin and triplet deliveries after IVF and ICSI was 78.2%, 21.0% and 0.8%, respectively. This gives a total multiple delivery rate of 21.8% compared with 22.7% in 2004 and 23.1% in 2003. In women <40 years of age, IUI-H was associated with a twin and triplet pregnancy rate of 11.0% and 1.1%, respectively. CONCLUSIONS Compared with earlier years, there was an increase in the reported number of ART cycles in Europe. Although fewer embryos were transferred per treatment, there was a marginal increase in pregnancy rates and a reduction in multiple deliveries.


Human Reproduction | 2009

Children born after cryopreservation of embryos or oocytes: a systematic review of outcome data

U.B. Wennerholm; Viveca Söderström-Anttila; Christina Bergh; Kristiina Aittomäki; J. Hazekamp; K.G. Nygren; Anders Selbing; A. Loft

BACKGROUND An estimated 3.5 million children have been born to date using assisted reproduction technologies. We reviewed the data in order to evaluate current knowledge of medical outcome for IVF/ICSI children born after cryopreservation, slow freezing and vitrification of early cleavage stage embryos, blastocysts and oocytes. METHODS A systematic review was performed. We searched the PubMed, Cochrane and Embase databases from 1984 to September 2008. Inclusion criteria for slow freezing of early cleavage stage embryos were controlled studies reporting perinatal or child outcomes. For slow freezing and vitrification of blastocysts and oocytes, and vitrification of early cleavage stage embryos, case reports on perinatal or child outcomes were also included. Three reviewers independently read and evaluated all selected studies. RESULTS For early cleavage embryos, data from controlled studies indicated a better or at least as good obstetric outcome, measured as preterm birth and low birthweight for children born after cryopreservation, as compared with children born after fresh cycles. Most studies found comparable malformation rates between frozen and fresh IVF/ICSI. For slow freezing of blastocysts and for vitrification of early cleavage stage embryos, blastocysts and oocytes, limited neonatal data was reported. We found no long-term child follow-up data for any cryopreservation technique. CONCLUSION Data concerning infant outcome after slow freezing of embryos was reassuring. Properly controlled follow-up studies of neonatal outcome are needed after slow freezing of blastocysts and after vitrification of early cleavage stage embryos, blastocysts and oocytes. In addition, child long-term follow-up studies for all cryopreservation techniques are essential.


British Journal of Obstetrics and Gynaecology | 2005

In vitro fertilisation in Sweden: obstetric characteristics, maternal morbidity and mortality

Bengt Källén; Orvar Finnström; K.G. Nygren; Petra Otterblad Olausson; Ulla-Britt Wennerholm

Objective  To investigate obstetric characteristics, maternal morbidity and mortality among Swedish women giving birth after in vitro fertilisation (IVF) treatment.


Human Reproduction | 2010

Trends in delivery and neonatal outcome after in vitro fertilization in Sweden: data for 25 years.

Bengt Källén; Orvar Finnström; Anna Lindam; Emma Nilsson; K.G. Nygren; P Otterblad Olausson

BACKGROUND Marked changes have occurred in in vitro fertilization (IVF) methodology during the past 25 years but also in characteristics of couples undergoing treatment. METHODS This study was based on 27 386 women undergoing IVF treatment from 1982 to 2006 and giving birth to 31 850 infants. Outcomes of deliveries were studied using Swedish health registers. Comparisons were made with all deliveries in the population (n = 2 603 601). Adjusted odds ratios were calculated when important changes in background rates had occurred. RESULTS There was a substantial increase in the use of intracytoplasmatic sperm injection (ICSI) and the transfer of cryopreserved embryos. Among all ICSI cases, the proportion using epididymal or testicular sperm varied between 5 and 10%. Maternal characteristics changed during the observation period but the median age remained relatively constant in spite of the increasing maternal age in the population. There was a decline in the rate of some maternal pregnancy diagnoses (notably pre-eclampsia, premature rupture of membranes) and some neonatal diagnoses (notably preterm births, low birthweight, cerebral hemorrhage, respiratory diagnoses, use of continuous positive airway pressure and mechanical ventilation, sepsis/pneumonia). Up till 1992, the twinning rate increased to a maximum of about 30% and then declined to 5% towards the end of the period whereas higher order multiples nearly disappeared. The total rate of infants with congenital malformations changed only little. CONCLUSIONS The decrease in unwanted outcomes can, to a large extent, be explained by the reduced rate of multiple births but was seen also among singletons. Other explanations can be sought in changes in the characteristics of patients undergoing IVF.


Human Reproduction | 2016

International Committee for Monitoring Assisted Reproductive Technologies world report: Assisted Reproductive Technology 2008, 2009 and 2010

S.J. Dyer; Georgina M. Chambers; J. de Mouzon; K.G. Nygren; Fernando Zegers-Hochschild; Ragaa T. Mansour; Osamu Ishihara; Manish Banker; G.D. Adamson

STUDY QUESTION What were utilization, outcomes and practices in assisted reproductive technology (ART) globally in 2008, 2009 and 2010? SUMMARY ANSWER Global utilization and effectiveness remained relatively constant despite marked variations among countries, while the rate of single and frozen embryo transfers (FETs) increased with a concomitant slight reduction in multiple birth rates. WHAT IS KNOWN ALREADY ART is widely practised in all regions of the world. Monitoring utilization, an approximation of availability and access, as well as effectiveness and safety is an important component of universal access to reproductive health. STUDY DESIGN, SIZE, DURATION This is a retrospective, cross-sectional survey on utilization, effectiveness and safety of ART procedures performed globally from 2008 to 2010. PARTICIPANTS, SETTING, METHODS Between 58 and 61 countries submitted data from a total of nearly 2500 ART clinics each year. Aggregate country data were processed and analyzed based on forms and methods developed by the International Committee for Monitoring Assisted Reproductive Technologies (ICMART). Results are presented at country, regional and global level. MAIN RESULTS AND THE ROLE OF CHANCE For the years 2008, 2009 and 2010, >4 461 309 ART cycles were initiated, resulting in an estimated 1 144 858 babies born. The number of aspirations increased by 6.4% between 2008 and 2010, while FET cycles increased by 27.6%. Globally, ART utilization remained relatively constant at 436 cycles/million in 2008 and 474 cycles/million population in 2010, but with a wide country range of 8-4775 cycles/million population. ICSI remained constant at around 66% of non-donor aspiration cycles. The IVF/ICSI combined delivery rate (DR) per fresh aspiration was 19.8% in 2008; 19.7% in 2009 and 20.0% in 2010, with corresponding DRs for FET of 18.8, 19.7 and 20.7%. In fresh non-donor cycles, single embryo transfer increased from 25.7% in 2008 to 30.0% in 2010, while the average number of embryos transferred fell from 2.1 to 1.9, again with wide regional variation. The rates of twin deliveries following fresh non-donor transfers were, in 2008, 2009 and 2010, 21.8, 20.5 and 20.4%, respectively, with a corresponding triplet rate of 1.3, 1.0 and 1.1%. Fresh IVF and ICSI carried a perinatal mortality rate per 1000 births of 22.8 (2008), 19.2 (2009) and 21.0 (2010), compared with 15.1, 12.8 and 14.6/1000 births following FET in the same periods of observation. The proportion of women aged 40 years or older undergoing non-donor ART increased from 20.8 to 23.2% from 2008 to 2010. LIMITATIONS, REASON FOR CAUTION The data presented are reliant on the quality and completeness of data submitted by individual countries. This report covers approximately two-thirds of the world ART activity. WIDER IMPLICATIONS OF FINDINGS The ICMART World Reports provide the most comprehensive global statistical census and review of ART utilization, effectiveness, safety and quality. While ART treatment continues to increase globally, the wide disparities in access to treatment and embryo transfer practices warrant attention by clinicians and policy makers. STUDY FUNDING/COMPETING INTERESTS The authors declare no conflict of interest and no specific support from any organizations in relation to this manuscript. ICMART acknowledges financial support from the following organizations: American Society for Reproductive Medicine; European Society for Human Reproduction and Embryology; Fertility Society of Australia; Japan Society for Reproductive Medicine; Japan Society of Fertilization and Implantation; Red Latinoamericana de Reproduccion Asistida; Society for Assisted Reproductive Technology; Government of Canada (Research grant), Ferring Pharmaceuticals (Grant unrelated to World Reports). TRIAL REGISTRATION not applicable.


Obstetrics & Gynecology | 2002

Neonatal outcome in pregnancies from ovarian stimulation

Bengt Källén; Petra Otterblad Olausson; K.G. Nygren

OBJECTIVE To study the neonatal outcome in pregnancies after ovarian stimulation, not including in vitro fertilization. The outcomes studied were multiple birth, preterm birth, and low birth weight among singletons, congenital malformations, and infant death. METHODS We identified 4029 women who delivered between 1995–1999 after ovarian stimulation alone and compared them with 438,582 women who neither had ovarian stimulation nor in vitro fertilization. We controlled for the confounding effect of year of birth, maternal age, parity, and length of subfertility before the pregnancy. RESULTS The twinning rate was 5.9% in the study group and 1.2% in the control group. The triplet rate was 0.5% in the study group and 0.02% in the control group. A nearly doubling of the rate of monozygotic twinning was indicated in the study group compared with the control group. There was an excess of singleton preterm births and low birth weight infants in the study group, but this was mainly explainable by confounding of maternal age, parity, and subfertility. The rates of congenital malformations and perinatal deaths were increased, also mainly explainable by maternal characteristics. No increase in specific types of congenital malformations was seen. CONCLUSION As the deviations in neonatal outcome after ovarian stimulation alone were reduced or disappeared when the confounding of maternal age, parity, and subfertility was taken into consideration, there is probably little direct effect of the stimulation procedure as such.


Human Reproduction | 2011

Malignancies among women who gave birth after in vitro fertilization

Bengt Källén; Orvar Finnström; Anna Lindam; Emma Nilsson; K.G. Nygren; P Otterblad Olausson

BACKGROUND Relatively few studies published to date have investigated IVF and cancer risk. In this study we compared the occurrence of cancer in women who gave birth after IVF with all other women who gave birth in the study period. METHODS All women who were treated with IVF and gave birth during the years 1982-2006 in Sweden were identified from all IVF clinics, and the occurrence of cancer in these women was identified by linkage with the nationwide Swedish cancer register. Comparison was made with Mantel-Haenszel odds ratios (ORs), adjusting for year of delivery and maternal age, parity and smoking. Cancer before IVF was only studied in first parity women. Specific cancer forms were also studied. RESULTS Among 24058 women who had been treated with IVF, 1279 appeared in the cancer register. The total number of women studied in the population was 1 394 061, and 95 775 of these were registered in the cancer register. The risk for cancer before IVF was increased [OR 1.37, 95% confidence interval (CI) 1.27-1.48] and was especially high for ovarian cancer (3.93). The risk for cancer after IVF was significantly lower (OR 0.74, 95% CI 0.67-0.82), mainly due to a lower than expected risk for breast and cervical cancer. The risk for ovarian cancer was increased but lower than the risk before IVF (2.13). CONCLUSIONS Cancer or cancer treatment may increase the risk for infertility leading to IVF. After IVF, in most cases with treatment with fertility hormones, a significantly low cancer risk was found. Ovarian cancer showed an increased risk, although lower than before IVF. One possible reason is ovarian pathology causing both infertility and an increased cancer risk.


British Journal of Obstetrics and Gynaecology | 2010

Selected neonatal outcomes in dizygotic twins after IVF versus non‐IVF pregnancies

Bengt Källén; Orvar Finnström; Anna Lindam; Emma Nilsson; K.G. Nygren; P Otterblad Olausson

Please cite this paper as: Källén B, Finnström O, Lindam A, Nilsson E, Nygren K‐G, Otterblad Olausson P. Selected neonatal outcomes in dizygotic twins after IVF versus non‐IVF pregnancies. BJOG 2010;


European Respiratory Journal | 2013

Association between preterm birth and intrauterine growth retardation and child asthma

Bengt Källén; Orvar Finnström; K.G. Nygren; P Otterblad Olausson

An association between preterm birth and an increased risk of childhood asthma has been demonstrated, but the importance of intrauterine growth retardation on asthma risk is unclear. Using data from Swedish health registers, infant characteristics and childhood asthma were studied. Analyses were made using Mantel–Haenszel methodology with adjustment for year of birth, maternal age, parity, smoking in early pregnancy and maternal body mass index. Preterm birth, birth weight and birth weight for gestational week were analysed and childhood asthma was evaluated from prescriptions of anti-asthmatic drugs. Neonatal respiratory problems and treatment for them were studied as mediating factors. Both short gestational duration and intrauterine growth retardation appeared to be risk factors and seemed to act separately. The largest effect was seen from short gestational duration. Use of mechanical ventilation in the newborn period and bronchopulmonary dysplasia were strong risk factors. A moderately increased risk was also seen in infants born large for gestational age. We conclude that preterm birth is a stronger risk factor for childhood asthma than intrauterine growth disturbances; however, the latter also affects the risk, and is also seen in infants born at term.

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A. Nyboe Andersen

Copenhagen University Hospital

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U.B. Wennerholm

Sahlgrenska University Hospital

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Christina Bergh

Sahlgrenska University Hospital

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P Otterblad Olausson

National Board of Health and Welfare

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Anja Pinborg

Copenhagen University Hospital

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Liv Bente Romundstad

Norwegian University of Science and Technology

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