Perinatal outcomes in singleton live births after fresh blastocyst-stage embryo transfer: a retrospective analysis of 67 147 IVF/ICSI cycles.

Are perinatal outcomes different between singleton live births conceived from fresh blastocyst transfer and those following the transfer of fresh cleavage-stage embryos? Fresh blastocyst transfer does not increase risks of preterm birth (PTB), low/high birth weight or congenital anomaly and does not alter the sex ratio at birth or prejudice the chance of having a healthy baby. Extended embryo culture is currently considered the best option for embryo selection, but concerns have been raised about increased risks of preterm delivery and large-for-gestational-age (LGA) babies. We conducted a retrospective cohort study based on data from the Human Fertilisation and Embryology Authority (HFEA) anonymised and cycle-based dataset in the UK between 1999 and 2011. Baseline characteristics were compared between in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) blastocyst-stage and cleavage-stage embryo transfer cycles using the χ2 test for categorical/dichotomised covariates and the Mann-Whitney test for continuous covariates. Statistical significance was set at <0.005. Poisson regression and multinomial logistic regression were used to establish relationships between perinatal outcomes and blastocyst-stage embryo transfer or cleavage-stage embryo transfer. Risk ratios (RRs), adjusted risk ratios (aRRs) and their 99.5% confidence intervals (CIs) were calculated as a measure of strength of associations. Results were adjusted for clinically relevant covariates. A sub-group analysis included women undergoing their first IVF/ICSI treatment. The level of significance was set at <0.05, and 95% CIs were calculated in the sub-group analysis. Of a total of 67 147 IVF/ICSI cycles, 11 152 involved blastocyst-stage embryo(s) and 55 995 involved cleavage-stage embryo(s). The two groups were comparable with regards to the risk of PTB (aRR, 1.00; 99.5% CI, 0.79-1.25), very-preterm birth (VPTB) (aRR, 1.00; 99.5% CI, 0.63-1.54), very-low birth weight (VLBW) (aRR, 0.84; 99.5% CI, 0.53-1.34), low birth weight (LBW) (aRR, 0.92; 99.5% CI, 0.73-1.16), high birth weight (HBW) (aRR, 0.94; 99.5% CI, 0.75-1.18) and very-high birth weight (VHBW) (aRR, 1.05; 99.5% CI, 0.66-1.65). The risk of congenital anomaly was 16% higher in the blastocyst-stage group than in the cleavage-stage group, but this was not statistically significant (aRR, 1.16; 99.5% CI, 0.90-1.49). The chance of having a healthy baby (born at term, with a normal birth weight and no congenital anomalies) was not altered by extended culture (aRR, 1.00; 99.5% CI, 0.93-1.07). Extended culture was associated with a marginal increase in the chance having a male baby in the main cycle-based analysis (aRR, 1.04; 99.5% CI, 1.01-1.09) but not in the sub-group analysis of women undergoing their first cycle of treatment (aRR, 1.04; 95% CI, 1.00-1.08). In the sub-group analysis, the risk of congenital anomalies was significantly higher after blastocyst-stage embryo transfer (aRR, 1.42; 95% CI, 1.12-1.81). This study is limited by the use of observational data and inability to adjust for key confounders, such as maternal smoking status and body mass index (BMI), which were not recorded in the HFEA dataset. As the main analysis was cycle-based and we were unable to link cycles within women undergoing more than one IVF/ICSI cycle, we undertook a sub-group analysis on women undergoing their first treatment cycle. Our findings should reassure women undergoing blastocyst-stage embryo transfer. For the first time, we have shown that babies born after blastocyst transfer have a similar chance of being healthy as those born after cleavage-stage embryos transfer. The research activity of Dr Nicola Marconi was funded by the scholarship 'A. Griffini-J. Miglierina', Fondazione Comunitaria del Varesotto, Provincia di Varese, Italy. The authors do not have any competing interests to disclose. N/A.

Marconi N ，Raja EA ，Bhattacharya S ，Maheshwari A ... -  《-》

A comparison of perinatal outcomes following fresh blastocyst or cleavage stage embryo transfer in singletons and twins and between singleton siblings.

Are perinatal outcomes following fresh blastocyst versus fresh cleavage stage embryo transfer (ET) different in singletons, twins, and between singleton siblings? Singleton babies conceived following fresh blastocyst, versus cleavage stage, ET are less likely to be small for gestational age (SGA) or to have a congenital anomaly (a result confirmed by comparing singleton siblings), while singletons born following fresh blastocyst ET were at a higher risk of being large for gestational age (LGA) than their sibling born following fresh cleavage stage ET. Blastocyst stage transfer is now the preferred strategy in most IVF units. Previous studies have suggested that babies conceived through blastocyst transfer are at increased risk of preterm birth and LGA. A national population-based retrospective cohort study was performed using linked Human Fertilisation and Embryology Authority (HFEA) data on 130 516 IVF and ICSI livebirths occurring from 103 062 women between 2000 and 2017. We included women who had at least one singleton livebirth resulting from IVF/ICSI fresh embryo treatment, using their own eggs and partner's sperm. A linked HFEA dataset was analysed using a multilevel framework, which accommodated repeated IVF cycles resulting in livebirths in the same woman. A population-averaged robust Poisson model was used for binary outcomes and a multinomial logistic regression model was used for categorical outcomes. Unadjusted and adjusted risk ratios (aRRs) (95% CI) were calculated. There were 130 516 livebirths in 103 062 women, including 86 630 singletons, 43 886 twin births, and 5384 pairs of singleton siblings. In comparison with fresh cleavage stage ET, fresh blastocyst stage transfer in singletons was associated with a lower risk of low birthweight (aRR = 0.92; 95% CI 0.86, 0.99), lower risk of being SGA (0.83; 0.78, 0.89), and lower risk of congenital anomaly (0.79; 0.71, 0.89). This analysis did not show an increase in risk associated with preterm birth (1.00; 0.94, 1.06), high birthweight (0.99; 0.93, 1.06), LGA (0.99; 0.93, 1.05), and the chance of healthy singleton baby (1.00; 1.00, 1.02). Twins resulting from fresh blastocyst stage ET were at slightly higher risk of preterm birth (1.05; 1.02, 1.10) compared with twins conceived following fresh cleavage stage ET. There was insufficient evidence for an association with the other perinatal outcomes. Singleton siblings born following fresh blastocyst stage ET were at a higher risk of being LGA (1.57; 1.01, 2.46) and at lower risk of having a congenital anomaly (0.52; 0.28, 0.97) compared to their singleton siblings born following cleavage stage ET. There was some evidence of excess risk of preterm birth (1.42; 0.97, 2.23) associated with blastocyst stage transfer. However, we could not confirm an association between blastocyst stage ET and low birthweight (1.35; 0.81, 2.27), high birthweight (1.19; 0.80, 1.77), and the chance of being a healthy baby (0.97; 0.86, 1.09). This was an observational study where we were unable to adjust for some key confounders, such as maternal smoking status and BMI, which may change from one pregnancy to another and are not recorded in the HFEA dataset. In the largest study of its kind, our analysis of singleton siblings, corrected for unmeasured, non-time varying maternal factors, confirms the previously reported association between blastocyst transfer and LGA babies, and shows a reduced risk of congenital anomaly following blastocyst transfer. Our sibling analysis did not confirm a decreased risk of low birthweight following blastocyst transfer. Overall, absolute risks are low and there is insufficient evidence to challenge the practice of extended culture of embryos. This project is financed by an NHS Grampian Endowment Research Grant, project number 17/052. One of the authors, S.B., was the Editor in Chief of HROpen until 31 December 2022 and would have been in that role when the paper was first submitted. As an invited speaker, S.B. has received travel expenses, accommodation and honoraria from Merck, Organon, and Ferring. A.M. has received travel expenses, accommodation, and honoraria from Merck Serono, Cook Medical, Pharmasure, Gedeon Richter, and Ferring. D.J.M. is currently a HROpen Associate Editor. N/A.

Raja EA ，Bhattacharya S ，Maheshwari A ，McLernon DJ ... -  《-》

Obstetric and perinatal risks in 4601 singletons and 884 twins conceived after fresh blastocyst transfers: a Nordic study from the CoNARTaS group.

Are obstetric and perinatal outcomes in pregnancies after fresh blastocyst transfer (BT) comparable with those born after fresh cleavage stage transfer (CT) and spontaneous conception (SC)? Fresh BT is associated with a higher risk of placental and perinatal complications. BT optimizes the selection of top-quality embryos and increases pregnancy and live birth rates per transfer compared to CT. However, concerns have been raised as extended culture duration may increase obstetric complications and impair perinatal outcomes. Previous studies have shown a higher risk of preterm birth (PTB) among infants born after BT compared with CT. Pregnancies after BT are also prone to a higher risk of same-sex twins after single embryo transfer (SET). A retrospective register-based cohort study used data from Denmark, Norway and Sweden including three cohorts: 56 557 singletons and 16 315 twins born after fresh IVF/ICSI cycles and 2 808 323 SC singletons in Denmark (birth years 1997-2014), Norway (2010-2015) and Sweden (2002-2015). Of the fresh IVF/ICSI singletons, 4601 were born after BT and 51 956 after CT. The twin cohort consisted of 884 fresh IVF/ICSI children born after BT and 15 431 fresh IVF/ICSI children born after CT. Data were obtained from a large Nordic cohort of children born after ART and SC initiated by the Committee of Nordic ART and Safety (CoNARTaS). The CoNARTaS cohort was established by cross-linking National ART-, Medical Birth-, and National Patients Registers using the unique personal identification number, allocated to every citizen in the Nordic countries. Obstetric and perinatal outcomes after BT, CT and SC were compared using logistic regression analysis. For perinatal outcomes, we calculated gestational age based on the date of oocyte pick-up (OPU) and in sensitivity analyses on data from Denmark and Norway, we also calculated gestational age based on the second-trimester ultrasonography (US) scan. Risk of pregnancies with same-sex twins after SET was used as a proxy for risk of monozygotic twins. Adjustments were made for child's sex, birth year, parity (0 or >1), maternal age, body mass index, smoking, educational level, fertilization method (IVF/ICSI), the number of aspirated oocytes, SET and country. Information on educational level and the number of aspirated oocytes was not available for Norway. Children born after frozen embryo transfer were not included. The birth cohorts were restricted according to the year in which BT was introduced in the different countries. A higher risk of placenta previa was found in singleton pregnancies after BT compared with CT (adjusted odds ratio [aOR] 2.11 [95% CI 1.76; 2.52]). Singletons born after BT had a higher risk of PTB (aOR 1.14 [95% CI 1.01; 1.29]) compared with CT singletons, when estimated based on OPU. Furthermore, an altered male/female ratio (aOR 1.13 [95% CI 1.06; 1.21]) with more males following BT compared with CT was seen. Risk of same-sex twins after SET was higher after single BT compared with single CT (aOR 1.94 [95% CI 1.42; 2.60]). Residual confounding cannot be excluded, in particular related to duration and cause of infertility that we could not adjust for due to lack of reliable data. Extended embryo culture to the blastocyst stage has the potential to compromise obstetric and perinatal outcomes in fresh cycles. These results are important since an increasing number of IVF/ICSI treatments are performed as BT. NORDFORSK (project no: 71450). The Research Fund of Rigshospitalet, Copenhagen University Hospital. ReproUnion Collaborative study, co-financed by the European Union, Interreg V ÖKS. Grants from Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (LUA/ALF 70940), Hjalmar Svensson Research Foundation. The Research Council of Norway through its Centres of Excellence funding scheme, project number 262700. None of the authors has any conflicts of interests to declare regarding this study. ISRCTN11780826.

Spangmose AL ，Ginström Ernstad E ，Malchau S ，Forman J ，Tiitinen A ，Gissler M ，Opdahl S ，Romundstad LB ，Bergh C ，Wennerholm UB ，Henningsen AA ，Pinborg A ... -  《-》

Pre-term birth and low birth weight following preimplantation genetic diagnosis: analysis of 88 010 singleton live births following PGD and IVF cycles.

Is PGD associated with the risk of adverse perinatal outcomes such as pre-term birth (PTB) and low birth weight (LBW)? There was no increase in the risk of adverse perinatal outcomes of PTB, and LBW following PGD compared with autologous IVF. Pregnancies resulting from ART are associated with a higher risk of pregnancy complications compared with spontaneously conceived pregnancies. The possible reason of adverse obstetric outcomes following ART has been attributed to the underlying infertility itself and embryo specific epigenetic modifications due to the IVF techniques. It is of interest whether interventions such as embryo biopsy as performed in PGD affect perinatal outcomes. Anonymous data were obtained from the Human Fertilization and Embryology Authority (HFEA), the statutory regulator of ART in the UK. The HFEA has collected data prospectively on all ART performed in the UK since 1991. Data from 1996 to 2011 involving a total of 88 010 singleton live births were analysed including 87 571 following autologous stimulated IVF ± ICSI and 439 following PGD cycles. Data on all women undergoing either a stimulated fresh IVF ± ICSI treatment cycle or a PGD cycle during the period from 1996 to 2011 were analysed to compare perinatal outcomes of PTB and LBW among singleton live births. Logistic regression analysis was performed adjusting for female age category, year of treatment, previous IVF cycles, infertility diagnosis, number of oocytes retrieved, whether IVF or ICSI was used and day of embryo transfer. There was no increase in the risk of PTB and LBW following PGD versus autologous stimulated IVF ± ICSI treatment, unadjusted odds of PTB (odds ratio (OR) 0.68, 95% CI: 0.46-0.99) and LBW (OR 0.56, 95% CI: 0.37-0.85). After adjusting for the potential confounders, there was again no increase in the risk of the adverse perinatal outcomes following PGD: PTB (adjusted odds ratio (aOR) 0.66, 95% CI: 0.45-0.98) and LBW (aOR 0.58, 95% CI: 0.38-0.88). Although the analysis was adjusted for a number of important confounders, the data set had no information on confounders such as smoking, body mass index and the medical history of women during pregnancy to allow adjustment. There was no information on the stage of embryo at biopsy, whether blastomere or trophectoderm biopsy. The demonstration that PGD is not associated with higher risk of PTB and LBW provides reassurance towards its current expanding application. No funding was obtained. There are no competing interests to declare.

Sunkara SK ，Antonisamy B ，Selliah HY ，Kamath MS ... -  《-》

Perinatal and maternal outcome after vitrification of blastocysts: a Nordic study in singletons from the CoNARTaS group.

Is transfer of vitrified blastocysts associated with higher perinatal and maternal risks compared with slow-frozen cleavage stage embryos and fresh blastocysts? Transfer of vitrified blastocysts is associated with a higher risk of preterm birth (PTB) when compared with slow-frozen cleavage stage embryos and with a higher risk of a large baby, hypertensive disorders in pregnancy (HDPs) and postpartum hemorrhage (PPH) but a lower risk of placenta previa when compared with fresh blastocysts. Transfer of frozen-thawed embryos (FETs) plays a central role in modern fertility treatment, limiting the risk of ovarian hyperstimulation syndrome and multiple pregnancies. Following FET, several studies report a lower risk of PTB, low birth weight (LBW) and small for gestational age (SGA) yet a higher risk of fetal macrosomia and large for gestational age (LGA) compared with fresh embryos. In recent years, the introduction of new freezing techniques has increased treatment success. The slow-freeze technique combined with cleavage stage transfer has been replaced by vitrification and blastocyst transfer. Only few studies have compared perinatal and maternal outcomes after vitrification and slow-freeze and mainly in cleavage stage embryos, with most studies indicating similar outcomes in the two groups. Studies on perinatal and maternal outcomes following vitrified blastocysts are limited. This registry-based cohort study includes singletons born after frozen-thawed and fresh transfers following the introduction of vitrification in Sweden and Denmark, in 2002 and 2009, respectively. The study includes 3650 children born after transfer of vitrified blastocysts, 8123 children born after transfer of slow-frozen cleavage stage embryos and 4469 children born after transfer of fresh blastocysts during 2002-2015. Perinatal and maternal outcomes in singletons born after vitrified blastocyst transfer were compared with singletons born after slow-frozen cleavage stage transfer and singletons born after fresh blastocyst transfer. Main outcomes included PTB, LBW, macrosomia, HDP and placenta previa. Data were obtained from the CoNARTaS (Committee of Nordic ART and Safety) group. Based on national registries in Sweden, Finland, Denmark and Norway, the CoNARTaS cohort includes all children born after ART treatment in public and private clinics 1984-2015. Outcomes were assessed with logistic multivariable regression analysis, adjusting for the country and year of birth, maternal age, body mass index, parity, smoking, parental educational level, fertilisation method (IVF/ICSI), single embryo transfer, number of gestational sacs and the child's sex. A higher risk of PTB (<37 weeks) was noted in the vitrified blastocyst group compared with the slow-frozen cleavage stage group (adjusted odds ratio, aOR [95% CI], 1.33 [1.09-1.62]). No significant differences were observed for LBW (<2500 g), SGA, macrosomia (≥4500 g) and LGA when comparing the vitrified blastocyst with the slow-frozen cleavage stage group. For maternal outcomes, no significant difference was seen in the risk of HDP, placenta previa, placental abruption and PPH in the vitrified blastocyst versus the slow frozen cleavage stage group, although the precision was limited.When comparing vitrified and fresh blastocysts, we found higher risks of macrosomia (≥4500 g) aOR 1.77 [1.35-2.31] and LGA aOR 1.48 [1.18-1.84]. Further, the risks of HDP aOR 1.47 [1.19-1.81] and PPH aOR 1.68 [1.39-2.03] were higher in singletons born after vitrified compared with fresh blastocyst transfer while the risks of SGA aOR 0.58 [0.44-0.78] and placenta previa aOR 0.35 [0.25-0.48] were lower. Since vitrification was introduced simultaneously with blastocyst transfer in Sweden and Denmark, it was not possible to explore the effect of vitrification per se in this study. The results from the change of strategy to vitrification of blastocysts are reassuring, indicating that the freezing technique per se has no major influence on the perinatal and maternal outcomes. The higher risk of PTB may be related to the extended embryo culture rather than vitrification. The study is part of the ReproUnion Collaborative study, co-financed by the European Union, Interreg V ÖKS. The study was also financed by grants from the Swedish state under the agreement between the Swedish government and the county councils, the ALF agreement (LUA/ALF 70940), Hjalmar Svensson Research Foundation and NordForsk (project 71 450). There are no conflicts of interest to declare. ISRCTN11780826.

Ginström Ernstad E ，Spangmose AL ，Opdahl S ，Henningsen AA ，Romundstad LB ，Tiitinen A ，Gissler M ，Wennerholm UB ，Pinborg A ，Bergh C ，Malchau SS ... -  《-》