Table. GWAS Used as Sources for 2-Sample Mendelian Randomization Analyses.
| Trait | Source | Setting | Country | Phenotype definition | No. of participants or No. of cases/controls |
|---|---|---|---|---|---|
| Exposure | |||||
| Educational level | Okbay et al,15 2022 | 71 Cohorts, including UK Biobank and 23andMe | Many, including UK and US | Self-reported years of education | 3 037 499 |
| Mediators | |||||
| T2D | Mahajan et al,16 2018 | 32 Cohorts, including deCODE and UK Biobank | Many, including Iceland and UK | Cases: T2D status based on a combination of diagnostic testing (fasting glucose or HbA1c level), recorded diagnosis codes, or self-report; controls: not diagnosed with T2D | 74 124/824 006 |
| BMI | Pulit et al,17 2019 | 30 Cohorts, including UK Biobank | Many, including UK | Measured BMI at study participation | 806 834 |
| Lifetime smoking score | Wootton et al,18 2020 | UK Biobank | UK | Self-reported smoking behavior, lifetime smoking index constructed to reflect smoking status (ever vs never), and smoking intensity among ever smokers | 462 690 |
| HDL-C level | Graham et al,19 2021 | 146 Cohorts, including deCODE, Million Veteran Program, and UK Biobank | Many, including Iceland, UK, and US | Measured blood levels of HDL-C level | 1 244 580 |
| SBP | Neale Laboratories, release 28 | UK Biobank | UK | Automated reading of SBP | 340 159 |
| Outcomes | |||||
| Ectopic pregnancy | FinnGen, release 820 | FinnGen | Finland | Cases: ICD-8 code 631, ICD-9 code 633, or ICD-10 code O00; controls: women without mentioned ICD codes | 5052/135 962 |
| Hyperemesis gravidarum | FinnGen, release 820 | FinnGen | Finland | Cases: ICD-8 code 638, ICD-9 code 643, or ICD-10 code O21; controls: women without mentioned ICD codes | 2092/163 702 |
| Gestational diabetes | FinnGen, release 820 | FinnGen | Finland | Cases: ICD-9 code 6488A or ICD-10 code O24.4; controls: women without mentioned ICD codes | 11 279/179 600 |
| Preeclampsia | Steinthorsdottir et al,21 2020 | 6 Cohorts, including deCODE | Many, including Iceland | Cases: maternal, varied by cohort (GOPEC, ALSPAC, and MOBA, pregnancy-onset hypertension and proteinuria; deCODE, ICD-10 codes O13, O14 or O15; SSI, ICD-8 code 637.04 and ICD-10 codes 014.1, O14.2 and O15; and FINRISK, ICD-8 codes 637.03, 637.04, 637.09, 637.10, 637.99, ICD-9 codes 6424-6427A, and ICD-10 codes O14.0, O14.1, O14.9, O15.0, O15.1, O15.2, and O15.9); controls: nonpreeclampsia pregnancies, except GOPEC and deCODE, which used women without preeclampsia | 7219/155 660 |
| Preterm birth | Solé-Navais et al,22 2023 | 18 Cohorts, including deCODE and UK Biobank | Many, including Iceland and UK | Singleton live birth with spontaneous onset; cases: delivery <259 d or ICD-10 code O60; controls: delivery between 273 to 294 d | 15 419/217 871 |
| Birth weight | Juliusdottir et al,23 2021 | 23 Cohorts, including deCODE and UK Biobank | Many, including Iceland and UK | Maternal GWAS of offspring birth weight | 270 002 |
Abbreviations: ALSPAC, Avon Longitudinal Study of Parents and Children; BMI, body mass index; GOPEC, UK Genetics of Pre-eclampsia study; GWAS, genome-wide association study; HbA1c, hemoglobin A1c; HDL-C, high-density lipoprotein cholesterol; ICD-8, International Classification of Diseases, Eighth Revision; ICD-9, International Classification of Diseases, Ninth Revision; ICD-10, International Statistical Classification of Diseases and Related Health Problems, Tenth Revision; MOBA, Norwegian Mother and Child Cohort Study; SBP, systolic blood pressure; SSI, Statens Serum Institut; T2D, type 2 diabetes; UK, United Kingdom.