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Influenza causes seasonal epidemics of respiratory infection in all parts of the world. Manifestations of influenza range from mild upper to severe lower respiratory tract infection. Medical risk groups are defined by factors predisposing for development of severe disease and are recommended annual vaccination as a protective measure. The previous Swedish treatment guidelines for influenza were issued in 2011, and a review of current evidence was deemed relevant. An important reason to revisit the guidelines is the recent approval of a novel drug for influenza treatment, baloxavir. Updated Swedish evidence-based guidelines created by a group of experts from various research areas, for the management of influenza are presented here. The work has been made in collaboration with the Public Health Agency of Sweden and the Swedish Reference Group for AntiViral therapy (RAV). The updated guidelines include guidelines for diagnostics, treatment and prophylaxis in special groups, including management of pregnant women and children with influenza. A new section about infection control has been added. Pharmacological treatment is covered in detail with regards to indication and dosage. Additionally, drug resistance and environmental aspects are discussed.

Study Question: Is preimplantation genetic testing (PGT) associated with adverse perinatal outcome and early childhood health?, Summary Answer: Children born after PGT had comparable perinatal outcomes to children born after IVF/ICSI and comparable findings regarding early childhood health., What Is Known Already: PGT is offered to couples affected by monogenic disorders (PGT-M) or inherited chromosomal aberrations (PGT-SR), limiting the risk of transferring the disorder to the offspring. PGT, an invasive technique, requires genetic analysis of one or up to ten cells from the embryo and is combined with IVF or ICSI. Several studies, most of them small, have shown comparable results after PGT and IVF/ICSI concerning perinatal outcome. Only a few studies with limited samples have been published on PGT and childhood health., Study Design, Size, Duration: We performed a register-based study including all singletons born after PGT (n = 390) in Sweden during 1 January 1996-30 September 2019. Singletons born after PGT were compared with all singletons born after IVF/ICSI (n = 61 060) born during the same period of time and with a matched sample of singletons (n = 42 034) born after spontaneous conception selected from the Medical Birth Register. Perinatal outcomes, early childhood health, and maternal outcomes were compared between pregnancies after PGT and IVF/ICSI as well as between pregnancies after PGT and spontaneous conception. Primary outcomes were preterm birth (PTB) and low birthweight (LBW) whereas childhood morbidity was the secondary outcome., Participants/materials, Setting, Methods: Data on women who went through PGT and gave birth were obtained from the local databases at the two PGT centres in Sweden, whereas data on IVF treatment for the IVF/ICSI group were obtained from the national IVF registers. These data were then cross-linked to national health registers; the Medical Birth Register, the Patient Register, and the Cause of Death Register. Logistic multivariable regression analysis and Cox proportional hazards models were performed with adjustment for relevant confounders., Main Results and the Role of Chance: The mean follow-up time was 4.6 years for children born after PGT and 5.1 years for children born after spontaneous conception, whereas the mean follow-up time was 9.0 years for children born after IVF/ICSI. For perinatal outcomes, PTB occurred in 7.7% of children after PGT and in 7.3% of children after IVF/ICSI, whereas the rates were 4.9% and 5.2% for LBW (adjusted odds ratio (AOR) 1.22, 95% CI 0.82-1.81 and AOR 1.17, 95% CI 0.71-1.91, respectively). No differences were observed for birth defects. In comparison to spontaneous conception, children born after PGT had a higher risk for PTB (AOR 1.73, 95% CI 1.17-2.58). Regarding early childhood health, the absolute risk of asthma was 38/390 (9.7%) in children born after PGT and 6980/61 060 (11.4%) in children born after in IVF/ICSI, whereas the corresponding numbers were 34/390 (8.7%) and 7505/61 060 (12.3%) for allergic disorders. Following Cox proportional hazards models, no significant differences were found for these outcomes. Sepsis, hypothyroidism, attention deficit hyperactivity disorder, autism spectrum disorders, mental retardation, cerebral palsy, and epilepsy were diagnosed in a maximum of three PGT children. No PGT children died during the follow-up period. Regarding maternal outcomes, the rates of placenta praevia and caesarean delivery were significantly higher after PGT in comparison to spontaneous conception (AOR 6.46, 95% CI 3.38-12.37 and AOR 1.52, 95% CI 1.20-1.92, respectively), whereas no differences were seen comparing pregnancies after PGT and IVF/ICSI., Limitations, Reasons for Caution: The rather small sample size of children born after PGT made it impossible to adjust for all relevant confounders including fertilization method and culture duration. Moreover, the follow-up time was short for most of the children especially in the PGT group, probably lowering the absolute number of diagnoses in early childhood., Wider Implications of the Findings: The results are reassuring and indicate that the embryo biopsy itself has no adverse effect on the perinatal, early childhood, or maternal outcomes. Although the results are comparable to IVF/ICSI also regarding early childhood outcome, they should be taken with caution due to the low number of children with diagnoses and short follow-up time. Long-term follow-up studies on children born after PGT are scarce and should be conducted considering the invasiveness of the technique., Study Funding/competing Interest(s): The study was financed by grants from the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (LUA/ALF 70940), the Board of National Specialised Medical Care at Sahlgrenska University Hospital and Hjalmar Svensson Research Foundation. There are no conflicts of interest to declare., Trial Registration Number: N/A., (© The Author(s) 2023. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology.)

The vast majority of IVF children are born healthy. Numerous studies have shown an increased risk of pre-term birth and low birthweight in comparison to spontaneous conception, both overall and for singletons. Moreover, in comparison to spontaneously conceived children, several studies have shown a modestly increased risk for birth defects. Most data on neurodevelopment, growth and physical health in children conceived after IVF show similar results as in children conceived spontaneously. However, the majority of children are still young and further research in adolescence and adulthood is needed. For mothers, the risk of placenta-mediated complications, such as hypertensive disorders of pregnancy, seems to be elevated. Both the infertility per se and the technical aspects have been suggested as contributors to the adverse outcome.  Even though there seems to be a modestly increased risk for adverse outcome for both the neonate and the mother, the absolute risks are low.

Study Question: Is transfer of vitrified blastocysts associated with higher perinatal and maternal risks compared with slow-frozen cleavage stage embryos and fresh blastocysts?, Summary Answer: 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., What Is Known Already: 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., Study Design, Size, Duration: 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., Participants/materials, Setting, Methods: 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., Main Results and the Role of Chance: 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., Limitations, Reasons for Caution: 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., Wider Implications of the Findings: 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., Study Funding/competing Interest(s): 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., Trial Registration Number: ISRCTN11780826., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Background: Frozen embryo transfer is associated with better perinatal outcome regarding preterm birth and low birthweight, yet higher risk of large for gestational age and macrosomia compared to fresh transfer. Further, higher rates of hypertensive disorders in pregnancy are noted after frozen embryo transfer. Whether these differences are due to the protocol used in frozen cycles remains unknown., Objective: To analyze the obstetric outcome after frozen embryo transfer depending on protocol used. Comparison was also made for frozen vs fresh transfer and for frozen transfer vs spontaneous conception., Study Design: A population-based retrospective registry study including all singletons born after frozen embryo transfer in Sweden from 2005 to 2015. The in vitro fertilization register was cross-linked with the Medical Birth Register, the Register of Birth Defects, the National Patient Register, the Swedish Neonatal Quality Register, and the Prescribed Drug Register. Singletons after frozen embryo transfer were compared depending on the presence of a corpus luteum in the actual cycle. All frozen transfer singletons were also compared with fresh transfer and spontaneous conception singletons. Primary outcomes were preterm birth (<37 w), low birthweight (<2500 g), hypertensive disorders in pregnancy, and postpartum hemorrhage (>1000 mL). Crude and adjusted odds ratio with 95% confidence interval were calculated and adjustment made for relevant confounders., Results: A total of 9726 singletons were born after frozen embryo transfer (natural cycles, n = 6297; stimulated cycles, n = 1983; programmed cycles, n = 1446), 24,365 after fresh transfer, and 1,127,566 after spontaneous conception. No significant differences were noticed for preterm birth and low birthweight between the different protocols used in frozen embryo transfer. Compared to natural and stimulated frozen cycles, programmed frozen cycles were associated with a higher risk of hypertensive disorders in pregnancy (adjusted odds ratio, 1.78; 95% confidence interval, 1.43-2.21 and adjusted odds ratio, 1.61; 95% confidence interval, 1.22-2,10, respectively) and postpartum hemorrhage (adjusted odds ratio, 2.63; 95% confidence interval, 2.20-3.13 and adjusted odds ratio, 2.87; 95% confidence interval, 2.29-2.60, respectively). Moreover, higher risks for postterm birth (adjusted odds ratio, 1.59; 95% confidence interval, 1.27-2.01 and adjusted odds ratio, 1.98; 95% confidence interval, 1.47-2.68) and macrosomia (adjusted odds ratio, 1.62; 95% confidence interval, 1.26-2.09 and adjusted odds ratio, 1.40; 95% confidence interval, 1.03-1.90) were detected. There were no significant differences in any outcomes between stimulated and natural cycles. Frozen cycles in general compared to fresh cycles and compared to spontaneous conceptions showed neonatal and maternal outcomes in agreement with earlier studies., Conclusion: No significant difference could be seen regarding preterm birth and low birthweight between the different protocols. However, higher rates of hypertensive disorders in pregnancy, postpartum hemorrhage, postterm birth, and macrosomia were detected in programmed cycles. Stimulated cycles had outcomes similar to natural cycles. These findings are important in view of the increasing use of frozen cycles and the new policy of freeze-all cycles in in vitro fertilization. The results suggest a link between the absence of corpus luteum and adverse obstetric outcomes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Previous studies have shown a higher risk of birth defects and preterm birth (PTB) in singletons born after blastocyst transfer as compared to singletons born after cleavage-stage transfer. Few studies have investigated the maternal outcomes., Objective: We sought to analyze the neonatal and maternal outcome after blastocyst transfer (day 5-6) compared to transfer of cleavage-stage embryos (day 2-3) and spontaneous conception., Study Design: This was a population-based retrospective registry study including all singleton deliveries after blastocyst transfer in Sweden from 2002 through 2013. The in vitro fertilization register was cross-linked with the Swedish Medical Birth Register, the Register of Birth Defects, and the National Patient Register. Deliveries after blastocyst transfer were compared with deliveries after cleavage-stage transfer and deliveries after spontaneous conception. Outcome measures included birth defects, PTB, low birthweight, small for gestational age, large for gestational age, perinatal mortality, placenta previa, placental abruption, and preeclampsia. Crude and adjusted odds ratios (AOR) with 95% confidence interval (CI) were calculated. Adjustment was made for year of birth of child, maternal age, parity, smoking, body mass index, years of involuntary childlessness, and child's sex and, for cleavage stage, also for number of oocytes retrieved, number of embryos transferred, and fresh/frozen embryo transfer., Results: There were 4819 singletons born after blastocyst transfer, 25,747 after cleavage-stage transfer, and 1,196,394 after spontaneous conception. Singletons born after blastocyst transfer had no increased risk of birth defects compared to singletons born after cleavage-stage transfer (AOR, 0.94; 95% CI, 0.79-1.13) or spontaneous conception (AOR, 1.09; 95% CI, 0.92-1.28). Perinatal mortality was higher in the blastocyst vs the cleavage-stage group (AOR, 1.61; 95% CI, 1.14-2.29). When comparing singletons born after blastocyst transfer to singletons born after spontaneous conception, a higher risk of PTB (<37 weeks) was seen (AOR, 1.17; 95% CI, 1.05-1.31). Singletons born after blastocyst transfer had a lower rate of low birthweight (AOR, 0.83; 95% CI, 0.71-0.97) as compared to cleavage-stage transfer. The rate of being small for gestational age was lower in singletons born after blastocyst transfer as compared to both cleavage-stage and spontaneous conception (AOR, 0.71; 95% CI, 0.56-0.88 and AOR, 0.70; 95% CI, 0.57-0.87, respectively). The risk of placenta previa and placental abruption was higher in pregnancies after blastocyst transfer as compared to pregnancies after cleavage-stage (AOR, 2.08; 95% CI, 1.70-2.55 and AOR, 1.62; 95% CI, 1.15-2.29, respectively) and spontaneous conception (AOR, 6.38; 95% CI, 5.31-7.66 and AOR, 2.31; 95% CI, 1.70-3.13, respectively)., Conclusion: No increased risk of birth defects was found in singletons born after blastocyst transfer. Perinatal mortality and risk of placental complications were higher in the blastocyst group as compared to the cleavage-stage group, observations that need further investigations., (Copyright © 2016 Elsevier Inc. All rights reserved.)