Academic performance in adolescents aged 15-16 years born after frozen embryo transfer compared with fresh embryo transfer: a nationwide registry-based cohort study.

OBJECTIVE: To assess academic performance in singletons aged 15-16 years conceived after frozen embryo transfer (FET) compared with singletons born after fresh embryo transfer (ET) in Danish cohorts born from 1995 to 2001. DESIGN: Danish national registry-based cohort study. SETTING: Danish national registries. POPULATION: All 6495 singletons conceived after assisted reproductive technology (ART) treatment in Denmark from 1995 to 2001 [FET (n) = 423; fresh ET (n) = 6072]. METHODS: Mean test scores on a national standardised and international comparable grading-scale. Comparisons of test score were first made in univariate analysis (Model 1) and secondly in a multivariate linear model (Model 2) adjusting for relevant reproductive and socio-demographic covariates such as the occupational and educational level of the parents. Sensitivity analyses on FET-IVF (in vitro fertilisation) versus fresh ET-IVF and FET-ICSI (intracytoplasmic sperm injection) versus fresh ET-ICSI were made. Linear mixed models were used to account for the correlation in test scores of siblings for continuous outcome. MAIN OUTCOME MEASURES: Mean overall test score and test score in Danish, mathematics, English, and physics/chemistry. RESULTS: Crude and adjusted mean test scores were similar for adolescents conceived after FET compared with fresh ET. The crude mean difference was +0.11 (95% CI -0.11; 0.34), and the adjusted mean difference was +0.12 (95% CI -0.09; 0.34). CONCLUSIONS: Adolescents conceived after FET had similar academic performance at 15-16 of years of age compared with children conceived after fresh ET. TWEETABLE ABSTRACT: Using frozen embryos in fertility treatment does not affect school performance in Danish adolescents aged 15-16 years.

Cumulative live birth rate prognosis based on the number of aspirated oocytes in previous ART cycles.

STUDY QUESTION: Is the number of aspirated oocytes in the first ART cycle associated with the cumulative live birthrates (CLBR) in subsequent cycles? SUMMARY ANSWER: The number of aspirated oocytes in the first cycle was associated with CLBR in subsequent cycles. Previous treatment response predicts outcome in future cycles. WHAT IS KNOWN ALREADY: Previous reports have shown a positive association between the number of retrieved oocytes and live birthrate per fresh treatment cycle. This has also been shown for the CLBR in one complete ART-cycle, including possible subsequent frozen-thawed transfers (FER). It has been shown that women with less than five oocytes in the first cycle have poorer outcome within six complete cycles than women with more than 12 oocytes, suggesting that the number of aspirated oocytes in the first cycle may be reproduced in later cycles. However, other studies have shown that an initial low treatment response may be improved with increased gonadotrophin start-dose. STUDY DESIGN, SIZE, DURATION: The Danish National IVF-registry includes all ART treatments in public and private clinics since 1994. Treatment-cycles were cross-linked with the Medical Birth Registry, identifying treatment-related births and natural conception births. This national cohort study includes all women starting ART treatments with homologous eggs between 2002 and 2011, N = 30 486. Subjects were followed for up to four fresh ART-cycles including subsequent FER-cycles (=four complete cycles), until the first livebirth, or until December 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS: The CLBR within 1-4 complete ART-cycles were calculated as the proportion of women with a livebirth, out of all women initiating ART-treatment, including drop-outs (no livebirth or no continued treatment within follow-up). In women with one year follow-up from last treatment, multivariate logistic regression analysis assessed impact of retrieved oocytes on CLBR, adjusting results for female age and cause of infertility. Hospital admission due to ovarian hyperstimulation syndrome (OHSS) was reported. MAIN RESULTS AND THE ROLE OF CHANCE: After one, two and three complete ART-cycles, the CLBRs attributable to ART treatment were 26.4% [95%CI 25.9-26.9], 42.6% [42.0-43.1] and 51.3% [50.7-51.9], respectively. The CLBR attributable to non-ART related conception (natural conception or intrauterine insemination) were 5.3% [5.0-5.6], 8.3% [8.0-8.7] and 10.6% [10.3-11.0], after one, two and three complete cycles. In women without a live birth in the first complete cycle, the number of aspirated oocytes predicted the outcome in the second and third cycle: When compared to women with 0-3 aspirated oocytes in the first cycle, the odds for live birth in the second and third cycle was 1.18 [1.07-1.30] for women with 4-9 aspirated oocytes in the first cycle, 1.41 [1.27-1.57] for women with 10-15 aspirated oocytes and 1.63 [1.42-1.88] for women with more than 15 aspirated oocytes. For women without a livebirth in the first and second cycle, the sum of aspirated oocytes predicted outcome in the third complete cycle. Women with a sum larger than six aspirated oocytes, had marked increased odds ratios for livebirth in the third complete cycle, compared to women with a sum of 0-6 oocytes in the first and second fresh cycle. Incidence of hospital-admission due to OHSS was 1.7% in the first cycle, decreasing to 1.3% and 1.0% in the second and third cycles. LIMITATIONS, REASONS FOR CAUTION: Although mandatory, there may be treatment-cycles not registered in the IVF-registry. Missing information in number of aspirated oocytes are most likely random losses of information. There were few observations in women with more than 15 aspirated oocytes and these birthrates should be interpreted cautiously. Information on gonadotrophin dose used for stimulation was not available, nor was information on dose adjustments in subsequent cycles. WIDER IMPLICATIONS OF THE FINDINGS: With these results we can counsel couples returning for fertility treatments, providing an age-stratified revised prognosis for chances of live birth and risk of OHSS, reflecting prior failed attempts and previous ovarian response. STUDY FUNDING/COMPETING INTEREST(S): This study was unconditionally funded by Ferring Pharmaceuticals and ReproUnion. The funders had no role in the study design, data collection and interpretation, or decision to submit the work for publication. The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER: The study was approved by the Danish Data Protection Agency (J.nr. 2012-41-1330).

The long-term prognosis for live birth in couples initiating fertility treatments.

STUDY QUESTION: What are the long-term chances of having a child for couples starting fertility treatments and how many conceive with ART, IUI and without treatment? SUMMARY ANSWER: Total 5-year live birthrates were strongly influenced by female age and ranged from 80% in women under 35-26% in women ≥40 years, overall, 14% of couples conceived naturally and one-third of couples starting treatments with intrauterine insemination delivered from that treatment. WHAT IS KNOWN ALREADY: Few studies report success rates in fertility treatments across a couple's complete fertility treatment history, across clinics, evaluating live births after insemination, ART and natural conceptions. STUDY DESIGN, SIZE, DURATION: This register-based national cohort study from Denmark includes all women initiating fertility treatments in public and private clinics with homologous gametes in 2007-2010. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women were identified in the Danish ART Registry and were cross-linked with the Medical Birth Registry to identify live births. Subfertile couples were followed 2 years (N = 19 884), 3 years (N = 14 445) and 5 years (N = 5165), or until their first live birth. Cumulative live birthrates were estimated 2, 3 and 5 years from the first treatment cycle, in all women, including drop-outs. Birthrates were stratified by type of first treatment (ART/IUI), mode of conception (ART/IUI/natural conception) and female age. MAIN RESULTS AND THE ROLE OF CHANCE: Within 5 years, in women aged <35 years (N = 3553), 35-39 years (N = 1156) and ≥40 years (N = 451), a total of 64%, 49% and 16% had a live birth due to treatment, respectively. Additionally, in women aged < 35 years, 35-39 years and ≥40 years, 16%, 11% and 10% delivered after natural conception, yielding total 5-year birthrates of 80%, 60% and 26%. In women starting treatments with IUI (N = 3028), 35% delivered after IUI within 5 years, 24% delivered after shift to ART treatments and 17% delivered after natural conception. Within 5 years from starting treatments with ART (N = 2137), 53% delivered after ART, 11% delivered after natural conception and 0.6% delivered after IUI. LIMITATIONS, REASONS FOR CAUTION: Birthrates are most likely higher compared to countries without national coverage of treatments and results are influenced by laws and regulations. Information on duration of infertility prior to treatment was not available. Future prospective intervention studies should focus on the role of expectant management. WIDER IMPLICATIONS OF THE FINDINGS: Our results can provide couples with a comprehensible age-stratified prognosis at start of treatment. STUDY FUNDING/COMPETING INTEREST(S): This study was unconditionally funded by Ferring Pharmaceuticals and the Augustinus foundation. All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: S.S.M. received an unconditional grant from Ferring Pharmaceuticals; A.A.H. has received personal fees from Ferring Pharmaceuticals not related to this work; A.N.A. reports grants and personal fees from Ferring Pharmaceuticals, personal fees from Merck Serono, grants and personal fees from MSD, outside the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work. TRIAL REGISTRATION NUMBER: The study was approved by the Danish Data Protection Agency (J.nr. 2012-41-1330).

Academic performance in adolescents born after ART-a nationwide registry-based cohort study.

STUDY QUESTION: Is academic performance in adolescents aged 15-16 years and conceived after ART, measured as test scores in ninth grade, comparable to that for spontaneously conceived (SC) adolescents? SUMMARY ANSWER: ART singletons had a significantly lower mean test score in the adjusted analysis when compared with SC singletons, yet the differences were small and probably not of clinical relevance. WHAT IS KNOWN ALREADY: Previous studies have shown similar intelligence quotient (IQ) levels in ART and SC children, but only a few have been on adolescents. Academic performance measured with standardized national tests has not previously been explored in a complete national cohort of adolescents conceived after ART. STUDY DESIGN, SIZE, DURATION: A Danish national registry-based cohort including all 4766 ART adolescents (n = 2836 singletons and n = 1930 twins) born in 1995-1998 were compared with two SC control cohorts: a randomly selected singleton population (n = 5660) and all twins (n = 7064) born from 1995 to 1998 in Denmark. Nine children who died during the follow-up period were excluded from the study. PARTICIPANTS/MATERIALS, SETTING, METHODS: Mean test scores on a 7-point-marking scale from -3 to 12 were compared, and adjustments were made for relevant reproductive and socio-demographic covariates including occupational and educational level of the parents. MAIN RESULTS AND THE ROLE OF CHANCE: The crude mean test score was higher in both ART singletons and ART twins compared with SC adolescents. The crude mean differences were +0.41 (95% CI 0.30-0.53) and +0.45 (95% CI 0.28-0.62) between ART and SC singletons and between ART and SC twins, respectively. However, the adjusted mean overall test score was significantly lower for ART singletons compared with SC singletons (adjusted mean difference -0.15 (95% CI -0.29-(-0.02))). For comparison, the adjusted mean difference was +2.05 (95% CI 1.82-2.28) between the highest and the lowest parental educational level, suggesting that the effect of ART is weak compared with the conventional predictors. The adjusted analyses showed significantly lower mean test scores in mathematics and physics/chemistry for ART singletons compared with SC singletons. Comparing ART twins with SC twins yielded no difference in academic performance in the adjusted analyses. Similar crude and adjusted overall mean test scores were found when comparing ART singletons and ART twins. LIMITATIONS, REASONS FOR CAUTION: Missing data on educational test scores occurred in 6.6% of adolescents aged 15-16 years for the birth cohorts 1995-1997, where all of the children according to their age should have passed the ninth grade exam at the time of data retrieval. As sensitivity analyses yielded no significant difference in the adjusted risk of having missing test scores between any of the groups, it is unlikely that this should bias our results. Adjustment for body mass index and smoking during pregnancy was not possible. WIDER IMPLICATIONS OF THE FINDINGS: As our results are based on national data, our findings can be applied to other populations. The findings of this paper suggest that a possible small negative effect of parental subfertility or ART treatment is counterbalanced by the higher educational level in the ART parents. STUDY FUNDING/COMPETING INTERESTS: The Danish Medical Association in Copenhagen (KMS) funded this study with a scholarship grant. None of the authors had any competing interests. TRIAL REGISTRATION NO STATISTICS DENMARK: 704676.

Large baby syndrome in singletons born after frozen embryo transfer (FET): is it due to maternal factors or the cryotechnique?

STUDY QUESTION: Are singletons born after frozen embryo transfer (FET) at increased risk of being born large for gestational age (LGA) and if so, is this caused by intrinsic maternal factors or related to the freezing/thawing procedures? SUMMARY ANSWER: Singletons after FET have an increased risk of being born LGA. This cannot solely be explained by intrinsic maternal factors as it was also observed in sibling pairs, where the sibling conceived after FET had an increased risk of LGA compared with the sibling born after Fresh embryo transfer. WHAT IS KNOWN ALREADY: FET singletons have a higher mean birthweight than singletons born after transfer of fresh embryos, and FET singletons may be at an increased risk of being born LGA. STUDY DESIGN, SIZE, DURATION: The national register-based controlled cohort study involves two populations of FET singletons. The first population (A: total FET cohort) consisted of all FET singletons (n = 896) compared with singletons born after Fresh embryo transfer (Fresh) (n = 9480) and also with that born after natural conception (NC; n = 4510) in Denmark from 1997 to 2006. The second population (B: Sibling FET cohort) included all sibling pairs, where one singleton was born after FET and the consecutive sibling born after Fresh embryo transfer or vice versa from 1994 to 2008 (n = 666). The sibling cohort included n = 550 children with the sibling combination first child Fresh/second child FET and n = 116 children with the combination first child FET/second child Fresh. PARTICIPANTS/MATERIALS, SETTING, METHODS: Main outcome measures were LGA defined as birthweight of >2 SD from the population mean (z-score >2) according to Marsáls curves. Macrosomia was defined as birthweight of >4500 g. Crude and adjusted odds ratios (AORs) of LGA and macrosomia were calculated for FET versus Fresh and versus NC singletons in the total FET cohort. Similarly, AOR was calculated for FET versus Fresh in the sibling cohort. Adjustments were made for maternal age, parity, child sex, year of birth and birth order in the sibling analyses. Meta-analyses were performed by pooling our data with the previously published cohort studies on LGA and macrosomia. MAIN RESULTS AND THE ROLE OF CHANCE: The AORs of LGA (z-score >2) and macrosomia in FET singletons versus singletons conceived after Fresh embryo transfer were 1.34 [95% confidence interval (95% CI) 0.98-1.80] and 1.91 (95% CI 1.40-2.62), respectively. The corresponding risks for FET versus NC singletons were 1.41 (95% CI 1.01-1.98) for LGA and 1.67 (95% CI 1.18-2.37) for macrosomia. The increased risk of LGA and macrosomia in FET singletons was confirmed in the sibling cohort also after adjustment for birth order. Hence, the increased risk of LGA in FET singletons cannot solely be explained by being the second born or by intrinsic maternal factors, but may also partly be related to freezing/thawing procedures per se. In the meta-analysis, the summary effects of LGA and macrosomia in FET versus singletons conceived after Fresh embryo transfer were AOR 1.54 (95% CI 1.31-1.81) and AOR 1.64 (95% CI 1.26-2.12), respectively. The corresponding figures for FET versus NC singletons were for LGA AOR 1.32 (95% CI 1.07-1.61) and macrosomia AOR 1.41 (95% CI 1.11-1.80), respectively. LIMITATIONS, REASONS FOR CAUTION: Adjustment for body mass index as a possible confounder was not possible. The size of the FET/Fresh sibling cohort was limited; however, the complete sibling cohort was sufficiently powered to explore the risk of LGA. A bias is very unlikely as data coding was based on national registers. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are consistent with the previous Nordic studies and thus can be generalized to the Nordic countries. The causes for LGA in FET singletons should be further explored. STUDY FUNDING/COMPETING INTEREST(S): No external funding was used for this project. None of the authors have any conflict of interest to declare.