The effect of ≤6 cm sized noncavity-distorting intramural fibroids on in vitro fertilization outcomes: a systematic review and meta-analysis

Importance: The potential detrimental effects of fibroids on natural fecundity and in vitro fertilization (IVF) outcomes may be influenced by their size, location, and number. The impact of small noncavity-distorting intramural fibroids on reproductive outcomes in IVF is still controversial, with conflicting results.

Objective(s): To determine whether women with noncavity-distorting intramural fibroids of ≤6 cm size have lower live birth rates (LBRs) in IVF than female age-matched controls with no fibroids.

Data sources: MEDLINE, Embase, Global Health, and Cochrane Library databases were searched from inception until July 1, 2022.

Study selection and synthesis: Women undergoing IVF with noncavity-distorting intramural fibroids ≤6 cm constituted the study group (n = 520), whereas women with no fibroid formed the controls (n = 1392). Female age-matched subgroup analyses were performed to evaluate the impact of different cut-offs for size (≤6, ≤4, and ≤2 cm), location (the International Federation of Gynecology and Obstetrics [FIGO] type-3), and the number of fibroids on reproductive outcomes. Mantel-Haenszel odds ratios (ORs) with 95% confidence intervals (CIs) were used for outcome measures. All statistical analyses were performed using RevMan 5.4.1 MAIN OUTCOME MEASURE(S): The primary outcome measure was LBR. Secondary outcome measures were clinical pregnancy, implantation, and miscarriage rates.

Result(s): After adopting the eligibility criteria, 5 studies were included in the final analysis. Women with ≤6 cm noncavity-distorting intramural fibroids had significantly lower LBRs (OR: 0.48, 95% CI: 0.36-0.65, 3 studies, I²=0; low-certainty evidence) compared with women with no fibroids. A significant reduction in LBRs was noted in ≤4 cm but not in the ≤2 cm subgroups. The FIGO type-3 fibroids of 2-6 cm size were associated with significantly lower LBRs. Owing to a lack of studies, the impact of the number of noncavity-distorting intramural fibroids (single vs. multiple) on IVF outcomes could not be assessed.

Conclusion(s): We conclude that 2-6 cm sized noncavity-distorting intramural fibroids have a deleterious effect on LBRs in IVF. The presence of FIGO type-3 fibroids of 2-6 cm size is associated with significantly lower LBRs. Conclusive evidence from high-quality randomized controlled trials, the reference standard study design for studies of health care interventions, is needed before myomectomy might be offered in daily clinical practice to women with such small fibroids before undergoing IVF treatment.