Fetal growth restriction in IVF pregnancies: outcomes and risk factors: a systematic review

Background: Fetal growth restriction (FGR) in in vitro fertilization pregnancies is a clinically important concern because assisted conception linked with altered placentation, singleton low birth weight, small-for-gestational-age birth, hypertensive disorders, and medically indicated preterm delivery. Objective: This systematic review evaluated outcomes and risk factors for FGR or related small-for-gestational-age birth in singleton pregnancies conceived through in vitro fertilization or intracytoplasmic sperm injection. Methods: A PRISMA-guided systematic review designed using PubMed, Scopus, Web of Science, and Cochrane Library searches. Eligible studies were original human studies evaluating FGR, small-for-gestational-age birth, birthweight percentile, or fetal growth trajectory after in vitro fertilization or intracytoplasmic sperm injection. Data synthesized qualitatively because exposure definitions, embryo-transfer protocols, comparator groups, and outcome definitions differed across studies. Results: Ten original studies were included in the results synthesis. Data linked fetal growth impairment with fresh embryo transfer, supraphysiologic estradiol, higher total gonadotrophin dose, vanishing twin syndrome, multiple embryo transfer, female infertility factors, and thin endometrium. Frozen embryo transfer was generally associated with higher birthweight and lower small-for-gestational-age frequency than fresh transfer, although it was linked with larger infants and hypertensive disorders in wider literature. Conclusion: FGR risk in in vitro fertilization pregnancies appears multifactorial. Clinical surveillance needs individualized attention to infertility background, stimulation intensity, embryo-transfer strategy, early multifetal loss, placental disease, and maternal vascular risk.