| 1. |
- Aradhya, Siddartha, et al.
(författare)
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Maternal age and the risk of low birthweight and pre-term delivery : a pan-Nordic comparison
- 2022
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 52:1, s. 156-164
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Tidskriftsartikel (refereegranskat)abstract
- Background: Advanced maternal age at birth is considered a risk factor for adverse birth outcomes. A recent study applying a sibling design has shown, however, that the association might be confounded by unobserved maternal characteristics.Methods: Using total population register data on all live singleton births during the period 1999–2012 in Denmark (N = 580 133; 90% population coverage), Norway (N = 540 890) and Sweden (N = 941 403) and from 2001–2014 in Finland (N = 568 026), we test whether advanced maternal age at birth independently increases the risk of low birthweight (LBW) (<2500 g) and pre-term birth (<37 weeks gestation). We estimated within-family models to reduce confounding by unobserved maternal characteristics shared by siblings using three model specifications: Model 0 examines the bivariate association; Model 1 adjusts for parity and sex; Model 2 for parity, sex and birth year.Results: The main results (Model 1) show an increased risk in LBW and pre-term delivery with increasing maternal ages. For example, compared with maternal ages of 26–27 years, maternal ages of 38–39 years display a 2.2, 0.9, 2.1 and 2.4 percentage point increase in the risk of LBW in Denmark, Finland, Norway and Sweden, respectively. The same patterns hold for pre-term delivery.Conclusions: Advanced maternal age is independently associated with higher risk of poor perinatal health outcomes even after adjusting for all observed and unobserved factors shared between siblings.
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| 2. |
- Barbuscia, Anna, et al.
(författare)
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Maternal age and risk of low birth weight and premature birth in children conceived through medically assisted reproduction. Evidence from Finnish population registers
- 2020
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Ingår i: Human Reproduction. - : Oxford University Press (OUP). - 0268-1161 .- 1460-2350. ; 35:1, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- STUDY QUESTION: Does the risk of low birth weight and premature birth increase with age among mothers who conceive through medically assisted reproduction (MAR)?SUMMARY ANSWER: Among MAR mothers, the risk of poorer birth outcomes does not increase with maternal age at birth except at very advanced maternal ages (40+).WHAT IS KNOWN ALREADY: The use of MAR treatments has been increasing over the last few decades and is especially diffused among women who conceive at older ages. Although advanced maternal age is a well-known risk factor for adverse birth outcomes in natural pregnancies, only a few studies have directly analysed the maternal age gradient in birth outcomes for MAR mothers.STUDY DESIGN, SIZE, DURATION: The base dataset was a 20% random sample of households with at least one child aged 0-14 at the end of 2000, drawn from the Finnish population register and other administrative registers. This study included children who were born in 1995-2000, because the information on whether a child was conceived through MAR or naturally was available only from 1995 onwards.PARTICIPANTS/MATERIALS, SETTING, METHODS: The outcome measures were whether the child had low birth weight (LBW, <2500 g at birth) and whether the child was delivered preterm (<37 weeks of gestation). Conceptions through MAR were identified by examining data on purchases of prescription medication from the National Prescription Register. Linear probability models were used to analyse and compare the maternal age gradients in birth outcomes of mothers who conceived through MAR or naturally before and after adjustment for maternal characteristics (i.e. whether the mother suffered from acute/chronic conditions before the pregnancy, household income and whether the mother smoked during pregnancy).MAIN RESULTS AND THE ROLE OF CHANCE: A total of 56026 children, 2624 of whom were conceived through MAR treatments, were included in the study. Among the mothers who used MAR to conceive, maternal age was not associated with an increased risk of LBW (the overall prevalence was 12.6%) at ages 25-39. For example, compared to the risk of LBW at ages 30-34, the risk was 0.22 percentage points lower (95% CI: -3.2, 2.8) at ages 25-29 and was 1.34 percentage points lower (95% CI: -4.5, 1.0) at ages 35-39. The risk of LBW was increased only at maternal ages >= 40 (six percentage points, 95% CI: 0.2, 12). Adjustment for maternal characteristics only marginally attenuated these associations. In contrast, among the mothers who conceived naturally, the results showed a clear age gradient. For example, compared to the risk of LBW (the overall prevalence was 3.3%) at maternal ages 30-34, the risk was 1.1 percentage points higher (95% CI: 0.6, 1.6) at ages 35-39 and was 1.5 percentage points higher (95% CI: 0.5, 2.6) at ages >= 40. The results were similar for preterm births.LIMITATIONS, REASON FOR CAUTION: A limited number of confounders were included in the study because of the administrative nature of the data used. Our ability to reliably distinguish mothers based on MAR treatment type was also limited. WIDERIMPLICATIONS OF THE FINDINGS: This is the first study to analyse the maternal age gradient in the risk of adverse birth outcomes among children conceived through MAR using data from a nationally representative sample and controlling for important maternal health and socio-economic characteristics. This topic is of considerable importance in light of the widespread and increasing use of MAR treatments.
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| 3. |
- Chanfreau, Jenny, et al.
(författare)
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Sibling group size and BMI over the life course : Evidence from four British cohort studies
- 2022
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Ingår i: Advances in Life Course Research. - : Elsevier BV. - 1040-2608. ; 53
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Tidskriftsartikel (refereegranskat)abstract
- Only children, here defined as individuals growing up without siblings, are a small but growing demographic subgroup. Existing research has consistently shown that, on average, only children have higher body mass index (BMI) than individuals who grow up with siblings. How this difference develops with age is unclear and existing evidence is inconclusive regarding the underlying mechanisms. We investigate BMI trajectories for only children and those with siblings up to late adolescence for four British birth cohorts and across adulthood for three cohorts. We use data on BMI from ages 2–63 years (cohort born 1946); 7–55 years (born 1958); 10–46 (born 1970) and 3–17 years (born 2000–2002). Using mixed effects regression separately for each cohort, we estimate the change in BMI by age comparing only children and those with siblings. The results show higher average BMI among only children in each cohort, yet the difference is substantively small and limited to school age and adolescence. The association between sibling status and BMI at age 10/11 is not explained by differential health behaviours (physical activity, inactivity and diet) or individual or family background characteristics in any of the cohorts. Although persistent across cohorts, and despite the underlying mechanism remaining unexplained, the substantively small magnitude of the observed difference and the convergence of the trajectories by early adulthood in all cohorts raises doubts about whether the difference in BMI between only children and siblings in the UK context should be of research or clinical concern. Future research could usefully be directed more at whether only children experience elevated rates of disease, for which high BMI is a risk factor, at different stages of the life course and across contexts.
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| 4. |
- Cozzani, Marco, et al.
(författare)
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The cognitive development from childhood to adolescence of low birthweight children born after medically assisted reproduction-a UK longitudinal cohort study
- 2021
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 50:5, s. 1514-1523
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous research has documented that children conceived through medically assisted reproduction (MAR) are at increased risk of poor birth outcomes, such as low birthweight (LBW), which are risk factors for stunted longer-term cognitive development. However, parents who undergo MAR to conceive have, on average, advantaged socioeconomic backgrounds which could compensate for the negative effects of being born LBW. Previous studies have not analysed whether the negative effects of LBW are attenuated among MAR conceived children.Methods: We draw on the UK Millennium Cohort Study (sweeps 1–6) which contains a sub-sample of (N = 396) MAR-conceived children. The dependent variable measures cognitive ability at around ages 3, 5, 7, 11 and 14. We examine the cognitive development of four groups of children: MAR-conceived low birthweight (MAR LBW); MAR-conceived non-low birthweight (MAR NLBW); naturally conceived low birthweight (NC LBW); naturally conceived non-low birthweight (NC NLBW). We estimate the two following linear regression models for each sweep: (i) a baseline model to examine the unadjusted association between cognitive development and low birthweight by mode of conception; and (ii) a model adjusted by socio-demographic family characteristics.Results: In baseline models, MAR LBW children [age 3: β = 0.021, 95% confidence interval (CI): -0.198, 0.241; age 5: β = 0.21, 95% CI: 0.009, 0.418; age 7: β = 0.163, 95% CI: -0.148, 0.474; age 11: β = 0.003, 95% CI: -0.318, 0.325; age 14: β = 0.156, 95% CI: -0.205, 0.517], on average perform similarly in cognitive ability relative to NC NLBW at all ages, and display higher cognitive scores than NC LBW children until age 7. When we account for family characteristics, differences are largely attenuated and become close to zero at age 14.Conclusions: Despite the higher incidence of LBW among MAR compared with NC children, they do not seem to experience any disadvantage in their cognitive development compared with naturally conceived children. This finding is likely explained by the fact that, on average, MAR children are born to socioeconomically advantaged parents.
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| 5. |
- Goisis, Alice, et al.
(författare)
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Advanced Maternal Age and the Risk of Low Birth Weight and Preterm Delivery : a Within-Family Analysis Using Finnish Population Registers
- 2017
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Ingår i: American Journal of Epidemiology. - : Oxford University Press (OUP). - 0002-9262 .- 1476-6256. ; 186:11, s. 1219-1226
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Tidskriftsartikel (refereegranskat)abstract
- Advanced maternal age at birth is considered a major risk factor for birth outcomes. It is unclear to what extent this association is confounded by maternal characteristics. To test whether advanced maternal age at birth independently increases the risk of low birth weight (< 2,500 g) and preterm birth (< 37 weeks' gestation), we compared between-family models (children born to different mothers at different ages) with within-family models (children born to the same mother at different ages). The latter procedure reduces confounding by unobserved parental characteristics that are shared by siblings. We used Finnish population registers, including 124,098 children born during 1987-2000. When compared with maternal ages 25-29 years in between-family models, maternal ages of 35-39 years and a parts per thousand40 years were associated with percentage increases of 1.1 points (95% confidence intervals: 0.8, 1.4) and 2.2 points (95% confidence intervals: 1.4, 2.9), respectively, in the probability of low birth weight. The associations are similar for the risk of preterm delivery. In within-family models, the relationship between advanced maternal age and low birth weight or preterm birth is statistically and substantively negligible. In Finland, advanced maternal age is not independently associated with the risk of low birth weight or preterm delivery among mothers who have had at least 2 live births.
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| 6. |
- Goisis, Alice, et al.
(författare)
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Birth outcomes following assisted reproductive technology conception among same-sex lesbian couples vs natural conception and assisted reproductive technology conception among heterosexual couples
- 2023
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Ingår i: Journal of the American Medical Association (JAMA). - 0098-7484 .- 1538-3598. ; 329:13, s. 1117-1119
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Tidskriftsartikel (refereegranskat)abstract
- Higher rates of adverse birth outcomes have been consistently reported among children conceived via assisted reproductive technology (ART) compared with children conceived through natural conception. Higher rates of multiple births in ART pregnancies partially explain the increased risk. It remains unclear to what extent the remaining difference can be attributed to the reproductive technology or to factors related to infertility, which is associated with an elevated risk of poorer birth outcomes. Same-sex lesbian couples undergo ART treatments generally without experiencing infertility. To distinguish the effects of reproductive treatment and infertility, we compared birth outcomes in ART pregnancies among same-sex lesbian couples vs natural conceptions and ART pregnancies among heterosexual couples.Methods: In Sweden, same-sex lesbian couples have been eligible to receive publicly funded ART treatments with donated sperm since 2005. This study included all births in Sweden from 2007 to 2018. Using pseudonymized personal identifiers, the Swedish National Quality Registry for Assisted Reproduction, which includes all ART treatments (in vitro fertilization [IVF], intracytoplasmic sperm injection [ICSI], and intrauterine insemination [IUI]), was linked to the medical birth register and the total population registers, which include information on birth outcomes and sociodemographic characteristics. We focused on first live births for ART and naturally conceived births because 97.3% of ART births among same-sex lesbian couples were first births. We analyzed 4 outcomes: birth weight (continuous), gestational age (continuous), low birth weight (binary, <2500 g), and preterm delivery (binary, <37 weeks of gestation). We estimated linear models on the continuous outcomes and linear probability models on the binary outcomes comparing ART-conceived births among same-sex lesbian couples (reference category) with ART births and naturally conceived births among heterosexual couples. For each outcome, we estimated unadjusted and adjusted (controlling for child sex, multiplicity, and maternal age at birth) models. We also estimated differences focusing on children conceived via IVF/ICSI because 99.4% of ART births among heterosexual couples were conceived via IVF/ICSI compared with 63.3% in same-sex couples, as same-sex couples often start treatments with IUI, which has a lower chance of success regardless of subfertility.Analyses were conducted using R version 4.1.1 (R Foundation). Statistical significance was set at P < .05 (2-sided). This study was approved by the Regional Ethical Review Board of Stockholm. Informed consent was not required for pseudonymized data.Results: During the study period, there were 868 ART births among same-sex lesbian couples, 23 488 ART births among heterosexual couples, and 456 898 naturally conceived births. ART-conceived births from same-sex and heterosexual couples showed a higher proportion of multiplicity (5.8% and 7.5%, respectively) than naturally conceived births (2.1%) (Table 1). Couples who conceived naturally had significantly lower birth weight and gestational age and similar risk of low birth weight and preterm delivery compared with same-sex couples who conceived via ART (Table 2). For example, birth weight was 3429.5 g in naturally conceived births vs 3460.2 g in same-sex ART births (adjusted difference, −76.2 g [95% CI, −113 to −39.3 g]; P < .001; low birth weight, 4.9% vs 6.7%, adjusted difference, 0.28 [95% CI, −1.11 to 1.66] percentage points; P = .70). Heterosexual couples who conceived via ART had statistically significantly lower birth weight and gestational age than same-sex couples (eg, birth weight: 3342.9 g vs 3460.2 g; adjusted difference, −97.4 g [95% CI, −134.8 to −59.9 g]; P < .001). Percentages of low birth weight and preterm birth were higher in ART conceptions among heterosexual couples vs same-sex couples but did not reach statistical significance (eg, low birth weight: 8.9% vs 6.7%; adjusted difference, 1.23 [95% CI, −0.17 to 2.65] percentage points; P = .09). The results were qualitatively similar when only considering IVF/ICSI-conceived children (Table 2).Discussion: This study demonstrated that same-sex lesbian couples undergoing ART had more favorable or similar birth outcomes to heterosexual couples who conceived naturally or underwent ART to conceive, suggesting that infertility-related factors rather than reproductive treatments contribute to higher rates of adverse birth outcomes in ART pregnancies. Limitations of the study include that the presence of infertility factors was not directly assessed and the relatively small sample size of same-sex couples reduced the statistical power of the study, particularly in the binary outcomes analyses.
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| 7. |
- Goisis, Alice, et al.
(författare)
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Medically assisted reproduction and birth outcomes : a within-family analysis using Finnish population registers
- 2019
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 393:10177, s. 1225-1232
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Tidskriftsartikel (refereegranskat)abstract
- Background Children born after medically assisted reproduction are at higher risk of adverse birth outcomes than are children conceived naturally. We aimed to establish the extent to which this excess risk should be attributed to harmful effects of treatment or to pre-existing parental characteristics that confound the association. Methods We used data from Finnish administrative registers covering a 20% random sample of households with at least one child aged 0-14 years at the end of 2000 (n=65 723). We analysed birthweight, gestational age, risk of low birthweight, and risk of preterm birth among children conceived both by medically assisted reproduction and naturally. First, we estimated differences in birth outcomes by mode of conception in the general population, using standard multivariate methods that controlled for observed factors (eg, multiple birth, birth order, and parental sociodemographic characteristics). Second, we used a sibling-comparison approach that has not been used before in medically assisted reproduction research. We compared children conceived by medically assisted reproduction with siblings conceived naturally and, thus, controlled for all observed and unobserved factors shared by siblings. Findings Between 1995 and 2000, 2776 (4%) children in our sample were conceived by medically assisted reproduction; 1245 children were included in the sibling comparison. Children conceived by medically assisted reproduction had worse outcomes than did those conceived naturally, for all outcomes, even after adjustments for observed child and parental characteristics-eg, difference in birthweight of -60 g (95% CI -86 to -34) and 2.15 percentage point (95% CI 1.07 to 3.24) increased risk of preterm delivery. In the sibling comparison, the gap in birth outcomes was attenuated, such that the relation between medically assisted reproduction and adverse birth outcomes was statistically and substantively weak for all outcomes-eg, difference in birthweight of -31 g (95% CI -85 to 22) and 1.56 percentage point (95% CI -1.26 to 4.38) increased risk of preterm delivery. Interpretation Children conceived by medically assisted reproduction face an elevated risk of adverse birth outcomes. However, our results indicate that this increased risk is largely attributable to factors other than the medically assisted reproduction treatment itself.
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| 8. |
- Goisis, Alice, et al.
(författare)
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Paternal age and the risk of low birth weight and preterm delivery : a Finnish register-based study
- 2018
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Ingår i: Journal of Epidemiology and Community Health. - : BMJ. - 0143-005X .- 1470-2738. ; 72:12, s. 1104-1109
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Tidskriftsartikel (refereegranskat)abstract
- Background Based on existing studies, there is no conclusive evidence as to whether and why paternal age matters for birth outcomes. Methods We used Finnish population registers on 106652 children born 1987-2000. We first document the unadjusted association between paternal age and the risk of low birth weight (LBW; <2500g) and preterm birth (<37 weeks' gestation). Second, we investigate whether the unadjusted association is attenuated on adjustment for child's, maternal and parental socioeconomic characteristics. Third, by adopting a within-family design which involves comparing children born to the same father at different ages, we additionally adjust for unobserved parental characteristics shared between siblings. Results The unadjusted results show that being born to a father aged 40+, as opposed to a father aged 30-34, is associated with an increased risk of LBW of 0.96% (95%CI 0.5% to 1.3%) and to a younger father (<25) with a 1% (95%CI 0.6% to 1.3%) increased risk. The increased risk at younger paternal ages is halved on adjustment for the child's characteristics and fully attenuated on adjustment for child/parental characteristics. The increased risk at paternal ages 40+ ispartially attenuated on adjustment for maternal characteristics (=0.62%; 95%CI 0.13% to 1.1%). Adjustment for unobserved parental characteristics shared by siblings further attenuates the 40+ coefficient (=0.4%; 95%CI -0.5% to -1.2%). Results for preterm delivery are similar. Conclusions The results underscore the importance of considering paternal age as a potential risk factor for adverse birth outcomes and of expanding research on its role and the mechanisms linking it to birth outcomes.
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| 9. |
- Keenan, Katherine, et al.
(författare)
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Health outcomes of only children across the life course : An investigation using Swedish register data
- 2023
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Ingår i: Population Studies. - : Informa UK Limited. - 0032-4728 .- 1477-4747. ; 77:1, s. 71-90
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Tidskriftsartikel (refereegranskat)abstract
- Only children (with no full biological siblings) are a growing subgroup in many high-income settings. Previous studies have largely focused on the short-term developmental outcomes of only children, but there is limited evidence on their health outcomes. Using Swedish population register data for cohorts born 1940–75, we compare the health of only children with that of children from multi-child sibling groups, taking into account birth order, family size, and presence of half-siblings. Only children showed lower height and fitness scores, were more likely to be overweight/obese in late adolescence, and experienced higher later-life mortality than those with one or two siblings. However, only children without half-siblings were consistently healthier than those with half-siblings, suggesting that parental disruption confers additional disadvantages. The health disadvantage was attenuated but not fully explained by adjustment for parental characteristics and after using within-family maternal cousin comparison designs.
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| 10. |
- Remes, Hanna, et al.
(författare)
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The Well-Being of Adolescents Conceived Through Medically Assisted Reproduction : A Population-Level and Within-Family Analysis
- 2022
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Ingår i: European Journal of Population. - : Springer Science and Business Media LLC. - 0168-6577 .- 1572-9885. ; 38:5, s. 915-949
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Tidskriftsartikel (refereegranskat)abstract
- Medically assisted reproduction (MAR) plays an increasingly important role in the realization of fertility intentions in advanced societies, yet the evidence regarding MAR-conceived children’s longer-term well-being remains inconclusive. Using register data on all Finnish children born in 1995–2000, we compared a range of social and mental health outcomes among MAR- and naturally conceived adolescents in population-averaged estimates, and within families who have conceived both through MAR and naturally. In baseline models, MAR-conceived adolescents had better school performance and the likelihood of school dropout, not being in education or employment, and early home-leaving were lower than among naturally conceived adolescents. No major differences were found in mental health and high-risk health behaviours. Adjustment for family sociodemographic characteristics attenuated MAR adolescents’ advantage in social outcomes, while increasing the risk of mental disorders. The higher probability of mental disorders persisted when comparing MAR adolescents to their naturally conceived siblings. On average, MAR adolescents had similar or better outcomes than naturally conceived adolescents, largely due to their more advantaged family backgrounds, which underscores the importance of integrating a sociodemographic perspective in studies of MAR and its consequences.
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