Uterine fibroid size modifications during pregnancy and puerperium: evidence from the first systematic review of literature

The influence of pregnancy on uterine fibroid size still remains an unsolved dilemma. Basing on current knowledge, physicians are not able to inform patients about the likelihood of uterine fibroids to modify their size during pregnancy. Study aim was to summarize available evidence concerning the size modifications of uterine fibroids during each trimester of pregnancy and during puerperium. The review was reported following the PRISMA guidelines and registered in PROSPERO (registration number: CRD42017071117). A literature search was conducted in electronic database (PubMed, Embase, Sciencedirect, the Cochrane library and Clinicaltrials.gov) until July 2017. All studies evaluating fibroids' changes during pregnancy and puerperium by ultrasound or magnetic-resonance-imaging were included. Descriptive characteristics of studies and patients were collected. The modifications of uterine fibroid diameter and volume were the outcome measures. Concerning the first trimester of pregnancy, all authors reported a significant growth of uterine fibroids. Contradictory evidence was found about uterine fibroid modifications during the second and third trimesters, mainly supporting a slowdown during mid pregnancy and a subsequent size reduction during late pregnancy. Concerning the overall modifications during pregnancy and puerperium, poor evidence quality suggests that uterine fibroids do not modify their volume/slightly enlarge during pregnancy and subsequently reduce in size during puerperium. Uterine fibroids seem to be subject to a non-linear trend of modifications during pregnancy and puerperium, which may vary from myoma to myoma. Adequate evidence supports uterine fibroid systematic enlargement during the first trimester of pregnancy, while inconsistent evidence is available about the changes of uterine fibroids during second and third trimesters. In addition, the overall modifications of myomas during pregnancy and puerperium remain unclear.