Obstet Gynecol 2022 Jun 2;139(6):1155-1167. Epub 2022 May 2.
Flinders Medical Centre, Adelaide, South Australia, and the Department of Obstetrics and Gynecology, Monash University, Clayton, Victoria, Australia; the Department of Obstetrics, Amsterdam Reproduction and Development Research Institute, Amsterdam UMC, University of Amsterdam, Amsterdam, the Julius Center for Health Sciences and Primary Care & Cochrane Netherlands, University Medical Center Utrecht, Utrecht University, Utrecht, the Department of Gynaecology and Obstetrics, GROW School of Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Department of Obstetrics and Gynecology, Haga Hospital, The Hague, the Department of Obstetrics and Gynecology, Gelre Hospitals Apeldoorn, Apeldoorn, and the Department of Obstetrics and Gynaecology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; the Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Atrium Health, Charlotte, North Carolina; the Maternal Fetal Medicine Unit, Department of Obstetrics, Vall d'Hebron Barcelona Hospital Campus, Universitat Autònoma de Barcelona, Barcelona, Spain; the Department of Obstetrics and Gynecology, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil; the Department of Obstetrics and Gynecology, Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel Aviv University, Tel Aviv, and the Department of Obstetrics and Gynecology, Samson Assuta Ashdod University Hospital, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; the Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, the Departments of Obstetrics and Gynecology, Medicine, Community Health Sciences, and Pediatrics, and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, and the Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada; the Department of Obstetrics and Gynecology, ASST-Spedali Civili, and the Department of Clinical and Experimental Sciences, University of Brescia, Brescia, and the Fetal Therapy Unit "Umberto Nicolini" and the Department of Women, Mother and Newborn, Vittore Buzzi Children's Hospital, University of Milan, Milan, Italy; the Department of Maternal Fetal Medicine, Osaka Women's and Children's Hospital, Osaka, Japan; the Department of Fetal Medicine, The Aga Khan University, Karachi, Pakistan; the Department of Obstetrics and Gynecology, University Hospitals of Leuven, Leuven, Belgium; the Department of Obstetrics and Gynecology, American University of Beirut Medical Center, Beirut, Lebanon; the Departments of Clinical Biochemistry and Obstetrics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark; the Epidemiology Branch, Division of Population Health Research, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, Maryland; the Mednax Center for Research, Education, Quality, and Safety, Sunrise, Florida; the Obstetrix Medical Group, Campbell, California; Unidad de Medicina Materno-Fetal, Instituto Valenciano de Infertilidad, Departamento de Pediatría, Obstetricia y Ginecología, and Servicio de Obstetricia, Hospital Universitario y Politécnico La Fe, Departamento de Pediatría, Obstetricia y Ginecología, Universidad de Valencia, Valencia, Spain; and the Fetal Medicine Unit, St George's Hospital, the Vascular Biology Research Centre, Molecular and Clinical Sciences Research Institute, St George's University of London, and the Twins Trust Centre for Research and Clinical Excellence, London, the Institute of Applied Health Research, University of Birmingham, Birmingham, and the Aberdeen Centre for Women's Health Research, University of Aberdeen, Aberdeen, United Kingdom.
Objective: First, to evaluate the risks of stillbirth and neonatal death by gestational age in twin pregnancies with different levels of growth discordance and in relation to small for gestational age (SGA), and on this basis to establish optimal gestational ages for delivery. Second, to compare these optimal gestational ages with previously established optimal delivery timing for twin pregnancies not complicated by fetal growth restriction, which, in a previous individual patient meta-analysis, was calculated at 37 0/7 weeks of gestation for dichorionic pregnancies and 36 0/7 weeks for monochorionic pregnancies.
Data Sources: A search of MEDLINE, EMBASE, ClinicalTrials.gov, and Ovid between 2015 and 2018 was performed of cohort studies reporting risks of stillbirth and neonatal death in twin pregnancies from 32 to 41 weeks of gestation. Studies from a previous meta-analysis using a similar search strategy (from inception to 2015) were combined. Women with monoamniotic twin pregnancies were excluded.
Methods Of Study Selection: Overall, of 57 eligible studies, 20 cohort studies that contributed original data reporting on 7,474 dichorionic and 2,281 monochorionic twin pairs.
Tabulation, Integration, And Results: We performed an individual participant data meta-analysis to calculate the risk of perinatal death (risk difference between prospective stillbirth and neonatal death) per gestational week. Analyses were stratified by chorionicity, levels of growth discordance, and presence of SGA in one or both twins. For both dichorionic and monochorionic twins, the absolute risks of stillbirth and neonatal death were higher when one or both twins were SGA and increased with greater levels of growth discordance. Regardless of level of growth discordance and birth weight, perinatal risk balanced between 36 0/7-6/7 and 37 0/7-6/7 weeks of gestation in both dichorionic and monochorionic twin pregnancies, with likely higher risk of stillbirth than neonatal death from 37 0/7-6/7 weeks onward.
Conclusion: Growth discordance or SGA is associated with higher absolute risks of stillbirth and neonatal death. However, balancing these two risks, we did not find evidence that the optimal timing of delivery is changed by the presence of growth disorders alone.
Systematic Review Registration: PROSPERO, CRD42018090866.