U.B. Wennerholm

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

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.

Risk of hypertensive disorders in pregnancies following assisted reproductive technology: a cohort study from the CoNARTaS group

STUDY QUESTION Is the risk of hypertensive disorders in pregnancies conceived following specific assisted reproductive technology (ART) procedures different from the risk in spontaneously conceived (SC) pregnancies? SUMMARY ANSWER ART pregnancies had a higher risk of hypertensive disorders, in particular following cryopreservation, with the highest risk seen in twin pregnancies following frozen-thawed cycles. WHAT IS KNOWN ALREADY The risk of hypertensive disorders is higher in ART pregnancies than in SC pregnancies. The increased risk may be partly explained by multiple pregnancies and underlying infertility, but a contribution from specific ART procedures has not been excluded. STUDY DESIGN, SIZE, DURATION Population-based cohort study, including sibling design with nationwide data from health registers in Sweden, Denmark and Norway. PARTICIPANTS/MATERIALS, SETTING, METHODS All registered ART pregnancies and a sample of SC pregnancies with gestational age ≥22 weeks from 1988 to 2007 were included. ART singleton pregnancies (n = 47 088) were compared with SC singleton pregnancies (n = 268 599), matched on parity and birth year. ART twin pregnancies (n = 10 918) were compared with SC twin pregnancies (46 674). We used logistic regression to estimate adjusted odds ratios and risk differences for hypertensive disorders in pregnancies following IVF, ICSI and fresh or frozen-thawed cycles. We also compared fresh and frozen-thawed cycles within mothers who had conceived following both procedures using conditional logistic regression (sibling analysis). MAIN RESULTS AND THE ROLE OF CHANCE Hypertensive disorders were reported in 5.9% of ART singleton and 12.6% of ART twin pregnancies. Comparing singleton pregnancies, the risk of hypertensive disorders was higher after all ART procedures. The highest risk in singleton pregnancies was seen after frozen-thawed cycles [risk 7.0%, risk difference 1.8%, 95% confidence interval (CI) 1.2-2.8]. Comparing twin pregnancies, the risk was higher after frozen-thawed cycles (risk 19.6%, risk difference 5.1%, 95% CI 3.0-7.1), but not after fresh cycles. In siblings, the risk was higher after frozen-thawed cycles compared with fresh cycles within the same mother (odds ratio 2.63, 95% CI 1.73-3.99). There were no clear differences in risk for IVF and ICSI. LIMITATIONS, REASONS FOR CAUTION The number of ART siblings in the study was limited. Residual confounding cannot be excluded. In addition, we did not have information on all SC pregnancies in each womans history, and could therefore not compare risk in ART versus SC pregnancies in the same mother. WIDER IMPLICATIONS OF THE FINDINGS Pregnancies following frozen-thawed cycles have a higher risk of hypertensive disorders, also when compared with fresh cycle pregnancies by the same mother. The safety aspects in frozen-thawed cycles merit further attention. STUDY FUNDING/COMPETING INTERESTS Funding was received from the European Society for Human Reproduction and Embryology, the University of Copenhagen, the Danish Agency for Science, Technology and Innovation, the Nordic Federation of Societies of Obstetrics and Gynecology and the Liaison Committee between the Central Norway Regional Health Authority and the Norwegian University of Science and Technology. None of the authors has any competing interests to declare.

Trends in perinatal health after assisted reproduction: a Nordic study from the CoNARTaS group

STUDY QUESTIONS Has the perinatal outcome of children conceived after assisted reproductive technology (ART) improved over time? SUMMARY ANSWER The perinatal outcomes in children born after ART have improved over the last 20 years, mainly due to the reduction of multiple births. WHAT IS KNOWN AND WHAT THIS PAPER ADDS A Swedish study has shown a reduction in unwanted outcomes over time in children conceived after ART. Our analyses based on data from more than 92 000 ART children born in four Nordic countries confirm these findings. STUDY DESIGN Nordic population-based matched cohort study with ART outcome and health data from Denmark, Finland, Norway and Sweden. PARTICIPANTS, SETTING AND METHODS We analysed the perinatal outcome of 62 379 ART singletons and 29 758 ART twins, born from 1988 to 2007 in four Nordic countries. The ART singletons were compared with a control group of 362 215 spontaneously conceived singletons. Twins conceived after ART were compared with all spontaneously conceived twins (n = 122 763) born in the Nordic countries during the study period. The rates of several adverse perinatal outcomes were stratified into the time periods: 1988-1992; 1993-1997; 1998-2002 and 2003-2007 and presented according to multiplicity. MAIN RESULTS AND ROLE OF CHANCE For singletons conceived after ART, a remarkable decline in the risk of being born preterm and very preterm was observed. The proportion of ART singletons born with a low and very low birthweight also decreased. Finally, the stillbirth and infant death rates have declined among both ART singletons and twins. Throughout the 20 year period, fewer ART twins were stillborn or died during the first year of life compared with spontaneously conceived twins, presumably due to the lower proportion of monozygotic twins among the ART twins. LIMITATIONS, REASONS FOR CAUTION We were not able to adjust for some potential confounders such as BMI, smoking, length or cause of infertility. The Nordic ART populations have changed over time, and in recent years, both less as well as severely reproductive ill couples are being treated. This may have affected the observed trends. WIDER IMPLICATIONS OF THE FINDINGS It is assuring that data from four countries confirm an overall improvement over time in the perinatal outcomes of children conceived after ART. Furthermore, data show the beneficial effect of single embryo transfer, not only in regard to lowering the rate of multiples but also concerning the health of singletons. STUDY FUNDING/COMPETING INTERESTS The European Society for Human Reproduction and Embryology (ESHRE), the University of Copenhagen and the Danish Agency for Science, Technology and Innovation has supported the project. The CoNARTaS group has received travel and meeting funding from the Nordic Federation of Obstetrics and Gynecology (NFOG). None of the authors has any competing interests to declare.

Risk of stillbirth and infant deaths after assisted reproductive technology: a Nordic study from the CoNARTaS group

STUDY QUESTION Is the risk of stillbirth and perinatal deaths increased after assisted reproductive technology (ART) compared with pregnancies established by spontaneous conception (SC)? SUMMARY ANSWER A significantly increased risk of stillbirth in ART singletons was only observed before 28 + 0 gestational weeks. WHAT IS KNOWN ALREADY The current literature indicates that children born after ART have an increased risk of perinatal death. The knowledge on stillbirth in ART pregnancies is limited. STUDY DESIGN, SIZE, DURATION A population based case-control study. PARTICIPANTS/MATERIALS, SETTING AND METHODS A total of 62 485 singletons and 29 793 twins born after ART in Denmark, Finland, Norway and Sweden, from 1982 to 2007, were compared with 362 798 spontaneously conceived (SC) singletons and 132 181 twins. MAIN RESULTS AND THE ROLE OF CHANCE The adjusted rate ratio for stillbirth at gestational weeks 22 + 0 to 27 + 6 was 2.08 [95% confidence interval (CI) 1.55-2.78] for ART versus SC singletons. After 28 + 0 gestational weeks there was no significant difference in the risk of stillbirth between ART and SC singletons. ART twins had a lower risk of stillbirth compared with SC twins, but when restricting the analysis to opposite-sex twins and excluding all monozygotic twins, there was no significant difference between the groups. Singletons conceived by ART had an overall increased risk of early neonatal death (adjusted odds ratio 1.54, 95% CI 1.28-1.85) and death within the first year after birth (1.45, 1.26-1.68). No difference regarding these two parameters was found when further adjusting for the gestational age [(0.97, 0.80-1.18) and (0.99, 0.85-1.16), respectively]. ART twins had a lower risk of early neonatal and infant deaths than SC twins, but no difference was found when restricting the analyses to opposite-sex twins. LIMITATIONS, REASON FOR CAUTION We were not able to adjust for potential confounders, such as a prior history of stillbirth, induction of labour, body mass index or smoking. WIDER IMPLICATIONS OF THE FINDINGS The risk of stillbirth in ART versus SC singletons was only increased for very early gestational ages (before 28 weeks). This might indicate that the current clinical management of ART pregnancies is sufficient regarding prevention of stillbirth during the third trimester. STUDY FUNDING/COMPETING INTEREST(S) No conflict of interest was reported. The European Society for Human Reproduction and Embryology (ESHRE), the University of Copenhagen, Denmark, the Danish Agency for Science, Technology and Innovation and Sahlgrenska University Hospital, Gothenburg, Sweden supported the project. The CoNARTaS group has received travel and meeting funding from the Nordic Society of Obstetrics and Gynecology (NFOG).

Women who gave birth to girls with Turner syndrome: maternal and neonatal characteristics.

BACKGROUND The aim was to identify maternal risk factors in women giving birth to girls with Turner syndrome (TS) and to describe the characteristics of newborns with TS. METHODS The Swedish Genetic Turner Register was cross-linked with the Swedish Medical Birth Register. Between 1973 and 2005, 494 children with TS were born. Maternal age, parity, height, smoking habits and neonatal characteristics; mode of delivery, gestational age, size at birth and Apgar score, were compared with women in the general population who gave birth to girls during the same period. RESULTS More women with advanced maternal age (40+) delivered girls with TS, 3.2% when compared with 1.8% in the general population [OR 1.83, 95% confidence interval (CI) 1.09-3.08, after adjustment for year of birth]. Maternal height was inversely associated with TS pregnancies (P = 0.005). Late preterm birth occurred in newborns with TS in 10.5% when compared with 4.8% in the general population (OR 2.23; 95% CI: 1.67-2.97, after adjustment for year of birth and maternal age). Newborns with TS had birthweight less than -2SD in 17.8% and birth length less than -2SD in 21.0% when compared with 3.5 and 3.4%, in the general population (OR 6.55; 95% CI: 5.12-8.38 and OR 8.69; 95% CI: 6.89-10.97, after adjustment for year of birth and maternal age). CONCLUSION Advanced maternal age and short stature were risk factors for giving birth to a girl with TS. More TS girls were born late preterm and were smaller for gestational age than non-TS girls in the general population.

Attitudes towards and management of single embryo transfer among Nordic IVF doctors

Background. The objective of this study was to investigate the attitudes towards and management of single embryo transfer (SET) among Nordic in vitro fertilisation (IVF) doctors, and to present the rate of SET and multiple pregnancies in the different countries. Methods. A questionnaire was sent to all IVF doctors in the Nordic countries (n = 198, 78.5% responded). Pregnancy rates, SET and multiple births rates were extracted from registries. Main outcome measure was attitudes and management of SET. Results. Almost all doctors thought that a twin pregnancy compared unfavourably to a singleton. A twin rate >10% was acceptable for 5% of Swedish doctors. Corresponding figures for Finnish, Danish and Norwegian doctors were 21, 35 and 35%, respectively. For a woman <36 years, performing her first cycle and with two good quality embryos, almost all doctors would recommend SET. For a woman ≥36 years in a similar situation, SET would be recommended only in Sweden and Finland. The pregnancy rate per embryo transfer (ET), the SET rate 2003, the multiple birth rate, and the estimated SET rate 2004 were 33.3, 21.5, 22.7 and 25% (Denmark), 31.3, 43.4, 14 and 51% (Finland), 40.5, 10.5, 26.5 and 16% (Iceland), 30.6, 18, 25.2 and 26% (Norway), and 35.3, 55.1, 11.8 and 71% (Sweden). Conclusions. The SET and multiple birth rates reflect the attitudes of Nordic IVF doctors to SET and multiple births well. When introducing SET, the attitude of the IVF doctor seems to be important.