value .
. | No of singletons . | Risk of CHD, ICSI vs. IVF . | Risk of CHD, ICSI vs. SC . | Risk of CHD, IVF vs. SC . | |||||
---|---|---|---|---|---|---|---|---|---|
. | ICSI = 42 385 . | IVF = 59 244 . | SC = 5 949 193 . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . |
Major CHDs (%) | 709 (1.67) | 895 (1.51) | 63 675 (1.07) | 1.11 (1.00–1.22) .041 | 1.07 (0.97–1.18) .200 | 1.57 (1.46–1.69) < .001 | 1.21 (1.12–1.31) < .001 | 1.42 (1.33–1.52) < .001 | 1.14 (1.07–1.22) < .001 |
Severe CHDs (%) | 124 (0.29) | 180 (0.30) | 14 390 (0.24) | 0.96 (0.77–1.21) .746 | 0.93 (0.74–1.17) .536 | 1.21 (1.01–1.44) .035 | 1.17 (0.98–1.40) .085 | 1.26 (1.08–1.46) .002 | 1.19 (1.03–1.39) .019 |
Major CHDs diagnosed within the first year of life according to the hierarchic classification of Botto | |||||||||
Lesion group 1 conotruncal, (%) | 37 (0.09) | 70 (0.12) | 4896 (0.08) | 0.74 (0.50–1.10) .136 | 0.73 (0.49–1.10) .130 | 1.06 (0.77–1.47) .721 | 0.94 (0.68–1.30) .688 | 1.44 (1.13–1.82) .003 | 1.28 (1.01–1.62) .046 |
Lesion group 2 non-conotruncal, (%) | 31 (0.07) | 42 (0.07) | 4500 (0.08) | 1.03 (0.65–1.64) .895 | 1.03 (0.64–1.67) .889 | 0.97 (0.68–1.38) .852 | 1.14 (0.80–1.63) .459 | 0.94 (0.69–1.27) .676 | 1.00 (0.74–1.36) .995 |
Lesion group 3 coarctation aortae, (%) | 21 (0.05) | 28 (0.05) | 2185 (0.04) | 1.05 (0.60–1.85) .870 | 0.99 (0.56–1.76) .977 | 1.35 (0.88–2.07) .172 | 1.06 (0.69–1.63) .795 | 1.29 (0.89–1.87) .185 | 1.07 (0.73–1.56) .733 |
Lesion group 4 VSD, (%) | 270 (0.64) | 356 (0.60) | 24 349 (0.41) | 1.06 (0.90–1.24) .468 | 1.03 (0.87–1.21) .752 | 1.56 (1.38–1.76) < .001 | 1.08 (0.96–1.22) .198 | 1.47 (1.32–1.63) < .001 | 1.09 (0.98–1.21) .115 |
Lesion group 5 ASD, (%) | 191 (0.45) | 209 (0.35) | 11 598 (0.19) | 1.28 (1.05–1.56) .014 | 1.18 (0.97–1.44) .101 | 2.32 (2.01–2.67) < .001 | 1.42 (1.23–1.64) < .001 | 1.81 (1.58–2.08) < .001 | 1.22 (1.06–1.41) .005 |
Lesion group 6 other CHDs, (%) | 159 (0.38) | 190 (0.32) | 16 147 (0.27) | 1.17 (0.95–1.45) .144 | 1.17 (0.94–1.45) .163 | 1.38 (1.18–1.62) < .001 | 1.33 (1.14–1.56) < .001 | 1.18 (1.02–1.36) .022 | 1.14 (0.99–1.32) .079 |
ART, assisted reproductive technology; ASD, atrial septal defect; CHD, congenital heart defect; CI, confidence interval; ICSI, intracytoplasmic sperm injection; IVF, in vitro fertilisation; OR, odds ratio; SC, spontaneous conception; VSD, ventricular septal defect.
a Adjustment for child’s year of birth, country of birth, maternal age, parity, maternal smoking, maternal diabetes, maternal CHD, and fresh and frozen embryo transfer.
b Adjustment for child’s year of birth, country of birth, maternal age, parity, maternal smoking, maternal diabetes, and maternal CHD.
c Major CHDs and severe CHDs according to the EUROCAT 1.5 definition. 32 , 33 .
d Lesion groups 1–6 according to Botto et al . 34
Table 6 presents the results for singletons born after frozen ( n = 18 875) and fresh ( n = 83 649) embryo transfer and SC ( n = 5 949 193). The occurrence of major CHDs among singletons born after FET was 1.82% ( n = 343) and among singletons born after fresh embryo transfer 1.54% ( n = 1286; adjusted OR 1.04; 95% CI 0.91–1.18; P = .603).
Risk of congenital heart defects by frozen and fresh embryo transfer in singletons conceived by assisted reproductive technology and spontaneous conception (Denmark 1994–2014, Norway 1984–2015, and Sweden 1987–2015)
. | No of singletons . | Risk of CHD, frozen vs. fresh embryo transfer . | Risk of CHD, frozen embryo transfer vs. SC . | ||||
---|---|---|---|---|---|---|---|
. | Frozen embryo transfer = 18 875 . | Fresh embryo transfer = 83 649 . | Spontaneous conception = 5 949 193 . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . |
Major CHDs , (%) | 343 (1.82) | 1286 (1.54) | 63 675 (1.07) | 1.19 (1.05–1.34) .006 | 1.04 (0.91–1.18) .603 | 1.71 (1.54–1.90) < .001 | 1.20 (1.08–1.34) .001 |
Severe CHDs , (%) | 64 (0.34) | 244 (0.29) | 14 390 (0.24) | 1.16 (0.88–1.53) .283 | 1.04 (0.77–1.41) .784 | 1.40 (1.10–1.79) .007 | 1.30 (1.02–1.67) .037 |
Major CHDs diagnosed within the first year of life according to the hierarchic classification of Botto | |||||||
Lesion group 1 conotruncal, (%) | 24 (0.13) | 85 (0.10) | 4896 (0.08) | 1.25 (0.80–1.97) .332 | 1.18 (0.72–1.95) .504 | 1.55 (1.03–2.31) .033 | 1.33 (0.89–1.98) .171 |
Lesion group 2 non-conotruncal, (%) | 15 (0.08) | 58 (0.07) | 4500 (0.08) | 1.15 (0.65–2.02) .638 | 1.43 (0.77–2.66) .261 | 1.05 (0.63–1.74) .848 | 1.26 (0.76–2.09) .375 |
Lesion group 3 coarctatio aortae, (%) | 12 (0.06) | 38 (0.05) | 2185 (0.04) | 1.40 (0.73–2.68) .310 | 1.13 (0.56–2.29) .726 | 1.73 (0.98–3.05) .058 | 1.22 (0.69–2.16) .488 |
Lesion group 4 VSD, (%) | 137 (0.73) | 493 (0.59) | 24 349 (0.41) | 1.23 (1.02–1.49) .031 | 1.00 (0.82–1.23) .963 | 1.78 (1.50–2.11) < .001 | 1.06 (0.89–1.25) .516 |
Lesion group 5 ASD, (%) | 91 (0.48) | 320 (0.38) | 11 598 (0.19) | 1.26 (1.00–1.59) .051 | 1.04 (0.80–1.34) .766 | 2.48 (2.02–3.05) < .001 | 1.33 (1.08–1.63) .008 |
Lesion group 6 other CHDs, (%) | 64 (0.34) | 292 (0.35) | 16 147 (0.27) | 0.97 (0.74–1.27) .833 | 0.95 (0.70–1.29) .755 | 1.25 (0.98–1.60) .075 | 1.20 (0.93–1.53) .155 |
. | No of singletons . | Risk of CHD, frozen vs. fresh embryo transfer . | Risk of CHD, frozen embryo transfer vs. SC . | ||||
---|---|---|---|---|---|---|---|
. | Frozen embryo transfer = 18 875 . | Fresh embryo transfer = 83 649 . | Spontaneous conception = 5 949 193 . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . |
Major CHDs , (%) | 343 (1.82) | 1286 (1.54) | 63 675 (1.07) | 1.19 (1.05–1.34) .006 | 1.04 (0.91–1.18) .603 | 1.71 (1.54–1.90) < .001 | 1.20 (1.08–1.34) .001 |
Severe CHDs , (%) | 64 (0.34) | 244 (0.29) | 14 390 (0.24) | 1.16 (0.88–1.53) .283 | 1.04 (0.77–1.41) .784 | 1.40 (1.10–1.79) .007 | 1.30 (1.02–1.67) .037 |
Major CHDs diagnosed within the first year of life according to the hierarchic classification of Botto | |||||||
Lesion group 1 conotruncal, (%) | 24 (0.13) | 85 (0.10) | 4896 (0.08) | 1.25 (0.80–1.97) .332 | 1.18 (0.72–1.95) .504 | 1.55 (1.03–2.31) .033 | 1.33 (0.89–1.98) .171 |
Lesion group 2 non-conotruncal, (%) | 15 (0.08) | 58 (0.07) | 4500 (0.08) | 1.15 (0.65–2.02) .638 | 1.43 (0.77–2.66) .261 | 1.05 (0.63–1.74) .848 | 1.26 (0.76–2.09) .375 |
Lesion group 3 coarctatio aortae, (%) | 12 (0.06) | 38 (0.05) | 2185 (0.04) | 1.40 (0.73–2.68) .310 | 1.13 (0.56–2.29) .726 | 1.73 (0.98–3.05) .058 | 1.22 (0.69–2.16) .488 |
Lesion group 4 VSD, (%) | 137 (0.73) | 493 (0.59) | 24 349 (0.41) | 1.23 (1.02–1.49) .031 | 1.00 (0.82–1.23) .963 | 1.78 (1.50–2.11) < .001 | 1.06 (0.89–1.25) .516 |
Lesion group 5 ASD, (%) | 91 (0.48) | 320 (0.38) | 11 598 (0.19) | 1.26 (1.00–1.59) .051 | 1.04 (0.80–1.34) .766 | 2.48 (2.02–3.05) < .001 | 1.33 (1.08–1.63) .008 |
Lesion group 6 other CHDs, (%) | 64 (0.34) | 292 (0.35) | 16 147 (0.27) | 0.97 (0.74–1.27) .833 | 0.95 (0.70–1.29) .755 | 1.25 (0.98–1.60) .075 | 1.20 (0.93–1.53) .155 |
a Adjustment for child’s year of birth, country of birth, maternal age, parity, maternal smoking, maternal diabetes, maternal CHD, and IVF/ICSI.
d Lesion groups 1–6 according to Botto et al. 34
Severe CHDs were detected in 594 children born after ART (0.35%) and in 19 375 children born after SC (0.26%; adjusted OR 1.30; 95% CI 1.20–1.42; P < .001; Table 2 ). Severe CHDs occurred among 0.31% ( n = 399) singletons born after ART and among 0.25% ( n = 18 539) singletons born after SC (adjusted OR 1.20; 95% CI 1.09–1.33; P < .001; Table 3 ). In multiples born after ART, the prevalence of severe CHDs was 0.44% ( n = 195; adjusted OR 1.46; 95% CI 1.22–1.75; P < .001 vs. singletons conceived after ART; Table 4 ). In multiples born after SC, the prevalence of severe CHDs was 0.43% ( n = 836; adjusted OR 1.70; 95% CI 1.58–1.82; P < .001 vs. spontaneously conceived singletons; Table 4 ). No significant difference in risk of severe CHDs was seen for multiples born after ART vs. multiples born after SC ( Table 3 ).
Severe CHDs occurred among singletons born after ICSI in 0.29% ( n = 124) and among singletons born after IVF in 0.30% ( n = 180; adjusted OR 0.93; 95% CI 0.74–1.17; P = .536; Table 5 ). In singletons born after FET, the prevalence of severe CHDs was 0.34% ( n = 64), and among singletons born after fresh embryo, transfer the prevalence was 0.29% ( n = 244; adjusted OR 1.04; 95% CI 0.77–1.41; P = .784).
Information on smoking was missing in ∼15% of the study population. A sensitivity analysis with no imputation on smoking did not alter results (adjusted OR for major CHDs 1.35; 95% CI 1.30–1.40, P < .001 for all countries combined, singletons and multiples).
In a second sensitivity analysis, we excluded observations from Norway and added an adjustment for maternal highest educational level, data which were not available for Norway. Including singletons and multiples from Denmark, Finland, and Sweden, the adjusted OR for major CHDs was 1.36 (95% CI 1.30–1.41, P < .001).
The analysis including Finnish data with validated major CHDs showed similar results as the main analysis (adjusted OR for major CHDs 1.35; 95% CI 1.30–1.41, P < .001 for all countries combined, and adjusted OR 1.31; 95% CI 1.19–1.44, P < .001 for Finland).
Including 2 783 464 infants born between 2006 and 2015, small differences in rates of any major CHDs and severe CHDs were found, compared with the whole time period (see Supplementary data online , Table S4 ). For major CHDs, all countries combined, the absolute rates during this period were 1.88% for ART and 1.42% for SC and 0.34% and 0.25% for severe CHDs, respectively. For Denmark, the absolute rates for both major CHDs and severe CHDs decreased, while for the other Nordic countries, the rates during the more recent time period stayed almost unchanged or varied slightly up or down. The adjusted ORs remain, however, rather unchanged (major CHDs, adjusted OR 1.31, 95% CI 1.24–1.37, P < .001; severe CHDs, adjusted OR 1.35, 95% CI 1.20–1.52, P < .001). Lastly, including only Swedish data and adding paternal CHDs as a covariate did not change the results for major CHDs (adjusted OR 1.22; 95% CI 1.16–1.29, P < .001).
According to the hierarchical CHD classification, the risk of CHDs was higher in children born after ART than in spontaneously conceived children for five of the six lesion groups: conotruncal defects, non-conotruncal defects, VSD, ASD, and other CHDs ( Table 2 ).
Singletons born after ART had increased risk for four lesion groups compared with spontaneously conceived singletons: conotruncal defects, VSD, ASD, and other CHDs ( Table 3 ).
For multiples born after ART vs. singletons born after ART a higher risk was seen for five of the six lesion groups: non-conotruncal defects, coarctation aortae, VSD, ASD, and other CHDs, and for multiples born after SC vs. spontaneously conceived singletons, the risk was increased for all six lesion groups ( Table 4 ).
In singletons born after ART, no difference was seen between ICSI and IVF ( Table 5 ), or between frozen and fresh embryo transfer ( Table 6 ) for any of the six lesion groups.
We analysed 10 selected major CHDs ( Table 7 ). In singletons, significantly increased risks in ART were seen for three CHDs: isomerism of atrial appendages, atrioventricular septal defects, and tetralogy of Fallot. Also including multiples, increased risk was seen also for pulmonary valve atresia (see Supplementary data online , Table S5 ).
Risk of selected major congenital heart defects in singletons conceived by assisted reproductive technology vs. spontaneous conception (Denmark 1994–2014, Finland 1990–2014, Norway 1984–2015, and Sweden 1987–2015)
. | No. of children . | Risk of CHD, ART vs. spontaneous conception . | ||
---|---|---|---|---|
. | ART = 127 275 . | SC = 7 380 916 . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . |
Common arterial truncus (Q20.0 ), (%) | 15 (0.01) | 613 (0.01) | 1.42 (0.85–2.37) .180 | 1.50 (0.89–2.52) .126 |
Double outlet right ventricle (Q20.1 ), (%) | 23 (0.02) | 831 (0.01) | 1.61 (1.06–2.43) .025 | 1.26 (0.83–1.91) .281 |
Complete transposition of the great vessel (Q20.3 ), (%) | 46 (0.04) | 2676 (0.04) | 1.00 (0.74–1.33) .983 | 0.99 (0.74–1.33) .949 |
Isomerism of atrial appendages with asplenia or polysplenia (Q20.6 ), (%) | 11 (0.01) | 196 (0.003) | 3.25 (1.77–5.97) < .001 | 2.79 (1.50–5.18) < .001 |
Atrioventricular septal defect (Q21.2 ), (%) | 90 (0.07) | 3327 (0.05) | 1.57 (1.27–1.93) < .001 | 1.28 (1.03–1.58) .023 |
Tetralogy of Fallot (Q21.3 ), (%) | 60 (0.05) | 2272 (0.03) | 1.53 (1.19–1.98) < .001 | 1.34 (1.03–1.73) .028 |
Pulmonary valve atresia (Q22.0 ), (%) | 29 (0.02) | 1407 (0.02) | 1.20 (0.83–1.73) .342 | 1.45 (1.00–2.10) .052 |
Tricuspid atresia and stenosis (Q22.4 ), (%) | 9 (0.01) | 447 (0.01) | 1.17 (0.60–2.26) .645 | 1.37 (0.70–2.67) .357 |
Hypoplastic left heart syndrome (Q23.4 ), (%) | 26 (0.02) | 1607 (0.02) | 0.94 (.64–1.38) .747 | 1.05 (0.71–1.54) .825 |
Coarctation aortae (Q25.1 ), (%) | 80 (0.06) | 4112 (0.06) | 1.13 (0.90–1.41) .285 | 0.97 (0.78–1.22) .808 |
. | No. of children . | Risk of CHD, ART vs. spontaneous conception . | ||
---|---|---|---|---|
. | ART = 127 275 . | SC = 7 380 916 . | Crude OR (95% CI) value . | Adjusted OR (95% CI) value . |
Common arterial truncus (Q20.0 ), (%) | 15 (0.01) | 613 (0.01) | 1.42 (0.85–2.37) .180 | 1.50 (0.89–2.52) .126 |
Double outlet right ventricle (Q20.1 ), (%) | 23 (0.02) | 831 (0.01) | 1.61 (1.06–2.43) .025 | 1.26 (0.83–1.91) .281 |
Complete transposition of the great vessel (Q20.3 ), (%) | 46 (0.04) | 2676 (0.04) | 1.00 (0.74–1.33) .983 | 0.99 (0.74–1.33) .949 |
Isomerism of atrial appendages with asplenia or polysplenia (Q20.6 ), (%) | 11 (0.01) | 196 (0.003) | 3.25 (1.77–5.97) < .001 | 2.79 (1.50–5.18) < .001 |
Atrioventricular septal defect (Q21.2 ), (%) | 90 (0.07) | 3327 (0.05) | 1.57 (1.27–1.93) < .001 | 1.28 (1.03–1.58) .023 |
Tetralogy of Fallot (Q21.3 ), (%) | 60 (0.05) | 2272 (0.03) | 1.53 (1.19–1.98) < .001 | 1.34 (1.03–1.73) .028 |
Pulmonary valve atresia (Q22.0 ), (%) | 29 (0.02) | 1407 (0.02) | 1.20 (0.83–1.73) .342 | 1.45 (1.00–2.10) .052 |
Tricuspid atresia and stenosis (Q22.4 ), (%) | 9 (0.01) | 447 (0.01) | 1.17 (0.60–2.26) .645 | 1.37 (0.70–2.67) .357 |
Hypoplastic left heart syndrome (Q23.4 ), (%) | 26 (0.02) | 1607 (0.02) | 0.94 (.64–1.38) .747 | 1.05 (0.71–1.54) .825 |
Coarctation aortae (Q25.1 ), (%) | 80 (0.06) | 4112 (0.06) | 1.13 (0.90–1.41) .285 | 0.97 (0.78–1.22) .808 |
ART, assisted reproductive technology; CI, confidence interval; OR, odds ratio.
a Adjustment for child’s year of birth, country of birth, maternal age.
b ICD-10 codes. Corresponding included ICD-8 and ICD-9 codes are shown in Supplementary data online , Table S2 . A child can have more than one CHD diagnosis.
In this large cohort study of 7.7 million liveborn children, including more than 171 000 children born after ART, we found that ART was associated with an increased risk of major CHDs as well as severe CHDs in both the overall ART population and in the ART singleton population, compared with spontaneously conceived children. Multiples, regardless of conception method, were associated with the highest risk of CHDs. Similar risks were observed in multiples conceived by ART and spontaneous conception, but this comparison is limited by the fact that we were missing information about chorionicity. The lower rate of monochorionic multiples in ART may give a false low risk in ART. Children conceived with ICSI did not seem to have an increased risk for CHDs compared with children conceived with IVF, and no significant difference was found between fresh and FET ( Structured Graphical Abstract ). The estimates were robust without any major changes after adjustments for available confounders or in sensitivity analyses.
Consistent with previous studies, our data showed higher occurrence of CHDs in pregnancies conceived by ART compared with spontaneously conceived pregnancies. 21–23 For specific CHDs, conflicting results have been reported. A large US study, including more than 11 million live births (singletons and multiples), of which 71 050 were conceived by ART, found a nearly three-fold increased risk of cyanotic CHDs in children born after ART, compared with children born after spontaneous conception, in adjusted analysis. 47 In a meta-analysis from 2018, Giorgione et al. analysed some specific CHDs in ART and spontaneously conceived singletons and multiples. They found lower occurrence of tetralogy of Fallot and transposition of the great arteries in the ART group. However, results were based on few events in the ART group. 21 In contrast, a French case–control study of 1583 CHD cases and 4104 controls (singletons and multiples) assessing four different major structural CHDs found 2.4-fold odds of tetralogy of Fallot in children born after ART. 27
The overall risk of birth defects in our cohort has been explored in a previous study. 11 The study showed an increased risk of major birth defects in singletons conceived using ICSI with fresh embryo transfer compared with spontaneously conceived singletons. The risk was increased for most organ systems including the heart. Detailed data on type of CHD group or specific diagnoses were not reported. Further, multifetal pregnancies, an important mediator in risk of CHDs, were not included in our previous study.
Congenital heart defects are a heterogeneous group of diseases including both severe, life-threatening defects and minor abnormalities. 34 , 48 , 49 While most children with CHDs survive to adulthood, health issues persist for many children with CHDs when they grow up. 50 , 51 Children and adolescents with CHDs have an 11-fold increased risk of ischaemic stroke, compared with the general population, although absolute risk is low. 48 , 52 For adults with CHDs, the risks of pulmonary arterial hypertension and endocarditis are increased. 53 , 54 Further, for young adults with CHDs, 1 in 12 develop atrial fibrillation, and 1 in 10 of these develop congestive heart failure, before 42 years of age. 52 , 55
The aetiology of CHDs is mainly unknown, but chromosomal abnormalities and other genetic and environmental factors are considered to predispose to CHDs. 36 , 56 Congenital heart defects may be part of a malformation syndrome due to chromosomal aneuploidy, such as Down syndrome (trisomy 21), Edward syndrome (trisomy 18), Patau syndrome (trisomy 13), Turner syndrome (monosomy X), and Klinefelter syndrome (XXY), or Mendelian syndromes as Alagille–Holt–Oram syndrome and Noonan syndrome. Several environmental risk factors have been identified for CHDs, including both young and advanced maternal age, high parity, smoking, obesity, maternal diabetes, and use of drugs during pregnancy, e.g. antiepileptic and antidepressant drugs. 38 , 41–44 , 57–61 Furthermore, women with a history of CHDs are considered to be at increased risk of having offspring with CHDs. 38 , 39 , 62 , 63 Also, low socioeconomic status has been found to be associated with CHDs. 64 , 65
Prenatal screening with foetal echocardiography for CHDs has been proposed to be beneficial for ART-conceived pregnancies. 21 , 66 , 67 and screening by foetal echocardiography is recommended by the American Heart Association for ART pregnancies. 66 Improved detection rate prenatally may offer the possibility for foetal therapy and/or specialized planning of delivery. However, this screening is still controversial and may cause increased costs and anxiety for the parents. 68–70 Further research is required to determine whether screening with foetal echocardiography, in addition to routine prenatal screening, will reduce morbidity and mortality for ART-conceived children when a major CHD is detected prenatally. In addition, preimplantation genetic testing may identify some CHDs of genetic origin and thereby contribute to decrease the CHDs among liveborn children.
Recent research has hypothesized that the placenta has a role in the development of CHDs, since placental vascular resistance has a direct impact on foetal circulation and thereby the developing foetal heart. 71 Children born with CHDs have smaller placentas with increased vascular abnormalities. 72 Further, studies also show a strong association between preeclampsia and CHDs, especially in early-onset and severe preeclampsia. 73 , 74 Pregnancies conceived with ART, in particular after FET, are associated with increased risk of preeclampsia, both for singleton and multifetal pregnancies. 75–77 An association between preeclampsia and CHD would, however, be expected to translate into a higher risk of CHD after FET which was not observed in the present study.
Twin pregnancies, especially monochorionic twins are associated with a higher risk of CHDs. 78 In recent years, multi-foetal pregnancies in ART have been declining, due to the introduction of the single embryo transfer policy. 79 However, the incidence of twin pregnancies continues to be elevated in ART-conceived pregnancies. 3 , 80
The main strength of this study is the large population with pooled nationwide data cross-linked from several high-quality national registries. Moreover, we explored specific CHD groups and specific assisted reproductive techniques. Detailed information enabled sub-analysis and adjustment for several confounders and comparisons according to multiplicity.
Some limitations should be considered when interpreting the results. Despite similar demography and healthcare systems, the rate of CHDs varied somewhat between countries. The follow-up for Norway was limited to birth, explaining the lower rate of CHDs in Norway. The reason for discrepancies between the other Nordic countries is not known but may be due to differences in registration policies and screening for foetal anomalies. The detection rate of major CHDs prenatally has increased substantially over time, as shown in Denmark leading to an increased termination of pregnancies, with a subsequent decrease in live-birth incidence of major CHDs. 18 This change might have had an impact on the results in this study, particularly since a greater proportion of the ART cohort are born in later years in this study. There were some differences in prenatal screening routines in the four Nordic countries during the study period. All countries had introduced a second trimester ultrasound (gestational week 18–21) between 2004–07 including foetal organ screening and where the large majority of women participated. Norway had a second trimester prenatal screening ultrasound during the whole study period. A first-trimester ultrasound to assess the nuchal fold and determine the risk of aneuploidy was more variably introduced with a higher frequency in Denmark and Finland. Although sensitivity analyses showed some differences in rates of major and severe CHDs in live births in the later years, this seemed to occur in similar way for both ART and spontaneous conception, resulting in only minor changes in adjusted ORs. However, still these changes over time in combination with the much increasing ART population are considered a limitation.
Furthermore, a limitation of this study is the lack of information on CHDs in miscarriages, termination of pregnancies, and stillbirths. This may result in bias if ART-conceived pregnancies have a different probability of prenatal diagnosis with subsequent termination compared with spontaneously conceived pregnancies. A French study by Tararbit et al. 81 found however no difference between ART and SC when evaluating the probability of prenatal diagnosis or termination of pregnancy for CHDs. A previous study on singletons from our cohort indicated similar risk of stillbirth after fresh and frozen embryo transfer compared with singletons conceived without medical assistance. 82 One study limitation is that we relied only on registry data and ICD codes with the potential for miscoding. Some ICD codes, e.g. the codes for VSDs, do not differentiate between severe and less severe CHDs, and we should have needed more data on echocardiography and surgical and other procedures for correct classification. However, we have used different classifications of major CHDs to identify the most complex CHDs. Furthermore, a sensitivity analysis using data from the Finnish birth defects registry with validated major CHDs showed similar results as the main result.
Children conceived after ovulation induction and intrauterine insemination were included in the SC group. This misclassification will, if anything, dilute the association between ART and CHD. 12 Other limitations are that we did not have information about causes of infertility and data on specific techniques used in assisted reproduction was not available from Finland. Finally, as in all observational studies residual confounding by unknown or unmeasured factors may remain.
Congenital heart defects are serious, although rare conditions. This large study reports a higher occurrence of CHDs after ART conception, both severe and less severe. The highest rates of CHDs were observed in children born in multiple pregnancies. No difference in CHDs was found between ICSI and IVF and neither between children born after fresh or frozen transfer. The findings of the current study should be conveyed to patients undergoing counselling before ART. Although the risk for major CHDs is higher in children born after ART, the absolute increase in risks seems to be modest. This study also emphasizes the importance of single embryo transfer to avoid the increased risks in multifetal pregnancies.
We thank all national registries providing individual data for this study.
Supplementary data are available atInterest European Heart Journal online.
All authors declare no disclosure of interest for this contribution.
The data that support the findings of this study are not available due to regulations restricted by law. Storage of data is arranged and ensured by Statistics Denmark. Research was feasible after receiving approvals from the Ethics Committees and registry-keeping authorities in each country. Administration of microdata from the national registries is regulated by the General Data Protection Regulation (GDPR) ensured by Statistics Denmark. Contact information for Statistics Denmark: Division of Research Services Statistics Denmark Sejrøgade 11 DK-2100 Copenhagen Denmark E-mail: [email protected] Phone: + 45 39 17 31 30.
The CoNARTaS has been supported by the Nordic Trial Alliance: a pilot project jointly funded by the Nordic Council of Ministers and NordForsk ( https://www.nordforsk.org/sv/research-areas/nordic-trial-alliance ) (grant number 71450; A.P.), the Central Norway Regional Health Authorities (grant number 46045000), the Norwegian Cancer Society (grant number 182356-2016; S.O.], the Nordic Federation of Obstetrics and Gynaecology [grant numbers NF13041, NF15058, NF16026, NF17043, and NF399 (2022–23)], the Interreg Öresund-Kattegat-Skagerrak European Regional Development Fund (ReproUnion project; AP), and the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (ALFGBG-70940; C.B.), and the Hjalmar Svensson Foundation (U.-B.W.). The funding sources had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.
Ethical approvals were obtained from Ethical Committee in Gothenburg, Sweden (Dnr 214-12, T422-12, T516-15, T233-16, T300-17, T1144-17, T121-18, T1071-18, 2019-02347, 2022-00903-02), and in Norway from the Regional Committee for Medical and Health Research Ethics (REK-Nord, 2010/1909). There are no requirements for ethical approval for registry-based studies in Denmark and Finland.
ISRCTN 11780826.
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How to Publish a Research Paper in Journal. Publishing a research paper in a journal is a crucial step in disseminating scientific knowledge and contributing to the field. Here are the general steps to follow: Choose a research topic: Select a topic of your interest and identify a research question or problem that you want to investigate ...
Every year, we accept and publish more than 470,000 journal articles so you are in safe hands. Publishing in an Elsevier journal starts with finding the right journal for your paper. We have tools, resources and services to help you at each stage of the publication journey to enable you to research, write, publish, promote and track your article.
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The first step in publishing a research paper should always be selecting the journal you want to publish in. Choosing your target journal before you start writing means you can tailor your work to build on research that's already been published in that journal.
How does one choose a journal in which to publish and what factors (impact factor, journal content) should be considered? In general, the most important factor to consider when choosing where to submit your article is the fit of the manuscript to the scope and profile of the journal; Aside from the quality of the science and writing, this is the largest factor that will determine whether a ...
3. Read the aims and scope and author guidelines of your target journal carefully. Once you have read and re-read your manuscript carefully several times, received feedback from your colleagues, and identified a target journal, the next important step is to read the aims and scope of the journals in your target research area.
Communicating research findings is an essential step in the research process. Often, peer-reviewed journals are the forum for such communication, yet many researchers are never taught how to write a publishable scientific paper. In this article, we explain ...
B ACKGROUND. The publication of original research in a peer-reviewed and indexed journal is the ultimate and most important step toward the recognition of any scientific work.However, the process starts long before the write-up of a manuscript. The journal in which the author wishes to publish his/her work should be chosen at the time of conceptualization of the scientific work based on the ...
A. Original research is published AOP — that is, Articles and Letters, and for the Nature journals that publish them, Brief Communications. Associated News and Views articles may be published ...
Communicating research findings is an essential step in the research process. Often, peer-reviewed journals are the forum for such communication, yet many researchers are never taught how to write a publishable scientific paper. In this article, we explain the basic structure of a scientific paper and describe the information that should be included in each section. We also identify common ...
Publishing research is only half the battle — promoting it to the right audience is equally important in achieving impact. This is essential when publishing research into alternative methods, as this can help to increase acceptance of such approaches. ... By implementing these strategies, published work from the journal can be effectively ...
Publishing a research paper in a peer-reviewed journal allows you to network with other scholars, get your name and work into circulation, and further refine your ideas and research. Before submitting your paper, make sure it reflects all the work you've done and have several people read over it and make comments.
Publishing a research paper as an undergraduate or as a first-time author can help you get academic funding and credit. It also improves your academic record. Self-Fulfilment: ... Each journal urges that the research work be in standard English. In case of any problem, authors can seek scientific editing services or manuscript editing services ...
If your article is accepted, you'll need to sign a publishing agreement. If your article is rejected, you can get help finding another journal from our transfer desk team. 7. Payment. If your article is open access, you'll need to pay a fee. Fees for OA publishing differ across journals. See relevant journal page for more information.
The most fundamental ingredient is excellent research. Work with the best scientists you can, in the best lab you can find. You will absorb the most about doing excellent science if you are surrounded by it during your training. ... Good news: The journal wants to publish your paper. Still, only on rare occasions will reviewers recommend that ...
There are several key benefits to publishing research in journals: DISCOVERABILITY. Publishing in journals can give your work visibility among other researchers in your field, outside of your immediate circle of contacts and colleagues. Journals can makes your work more discoverable, as they are already being read by circles of interested readers.
Undergraduate research journals aren't indexed in many of the sources we typically use for finding journals, so lists of academic journals focused on publishing undergraduate research compiled by universities and organizations are good starting places for finding a place to publish your work:
This article provides an overview of writing for publication in peer-reviewed journals. While the main focus is on writing a research article, it also provides guidance on factors influencing journal selection, including journal scope, intended audience for the findings, open access requirements, and journal citation metrics.
Successfully publishing a research paper in international journals is a key part of a researcher's work and can shape the trajectory of their careers. This not only helps advance the knowledge in a researcher's field of work but also helps them build networks and even secure funding for new research in the long run. However, irrespective of the discipline, a beginner with even a brilliant ...
Choosing a journal that's right for your research can be more complex than it seems. You want to publish in a journal that will help your study to reach its intended audience. Your research has a better chance of attracting readers, accumulating citations, and impacting the field when your colleagues can easily find it.
Why do we need to publish research paper? Your published paper can help in the public understanding of a research question. Publishing helps establish you as an expert in your field of knowledge. Peer-reviewed publication provides evidence that helps in the evaluation of merit of research funding requests. Now going to our main topic.
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Investigate the publisher. Most scholarly articles are published in peer-reviewed journals, e.g. Strategic Management Journal or Journal of Labor Economics; Browse the structure of the article. Scholarly articles often contain multiples sections and have headers such as introduction, literature review, methodology, discussion, conclusion, etc.
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His research focuses on inflation, macroeconomics, and monetary economics. He is published widely in top economics journals and has extensive research experience focused on inflation expectations. Pfajfar holds a BS in economics from the University of Ljubljana, an MS in economics from the University of Warwick, and a PhD in economics from the ...
A federal antitrust lawsuit against a group of megapublishers highlights how academia's system of rewarding researchers for publishing in certain journals has undermined their leverage. A prolific neuroscientist is accusing some of the same companies that published her work in top-tier peer-reviewed journals of conspiring "to hold the careers of scholars hostage" in the name of ...
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Published by the American Physical Society
BACKGROUND: BMP9 (bone morphogenetic protein 9) is a member of the TGF-β (transforming growth factor β) family of cytokines with pleiotropic effects on glucose metabolism, fibrosis, and lymphatic development. However, the role of BMP9 in myocardial infarction (MI) remains elusive. METHODS: The expressional profiles of BMP9 in cardiac tissues and plasma samples of subjects with MI were ...
SEATTLE - September 27, 2024 - Researchers at Fred Hutch Cancer Center identified a substantial increase over the past decade in the proportion of patients with cancer in the U.S. who participate in pharmaceutical industry sponsored clinical trials compared to those conducted with federal government support. Published in The Journal of Clinical Oncology and presented at the ASCO Quality ...
The main findings were that assisted reproductive technology (ART) was associated with an increased risk of major congenital heart defects (CHDs) as well as severe CHDs in liveborn children with follow-up to 1 year of age, compared with spontaneous conception (SC).