Evaluating in vitro fertilization outcomes of patients with low body mass index following frozen-thawed embryo transfer

Maternal underweight does not adversely affect the outcomes of IVF/ICSI and frozen embryo transfer cycles or early embryo development

OBJECTIVE

To compare assisted reproductive technology (ART) outcomes and preimplantation embryo development between underweight and normal-weight women.

METHODS

This retrospective cohort study included 26 underweight women (body mass index [BMI] < 18.50 kg/m²) and 104 normal-weight women (BMI >20 and <24.9 kg/m²) who underwent a total of 204 in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles and 358 fresh/frozen embryo transfers (ET) in our institution between January 2016 and December 2018. Statistical analyses compared selected ART outcomes (ovarian stimulation, fertilization, and pregnancy) between both weight groups. Morphokinetic and morphological parameters were also compared between 346 and 1467 embryos of underweight and normal-weight women, respectively.

RESULTS

The mean ± standard deviation age of the underweight and normal-weight women was similar (31.6 ± 4.17 vs 32.4 ± 3.59 years; p = .323). There were no differences in the peak estradiol levels, the number of retrieved oocytes, the number of metaphase II oocytes, and the oocyte maturity rates between the two groups. The IVF/ICSI fertilization rates and the number of embryos suitable for transfer or cryopreservation were similar for both groups. All morphokinetic parameters that were evaluated by means of time-lapse imaging as well as the morphological characteristics were comparable between low and normal BMI categories. There were no significant differences in pregnancy achievement, clinical pregnancy, live births, and miscarriage rates between the suboptimal and optimal weight women.

CONCLUSION

Underweight status has no adverse impacts on the outcomes of IVF/ICSI with either fresh or frozen ET or on preimplantation embryo development and quality.

Association between abnormal body mass index and pregnancy outcomes in patients following frozen embryo transfer: a systematic review and meta-analysis

BACKGROUND

There has been increasing interest in the relationship between body mass index(BMI) and pregnancy outcomes, especially in women undergoing frozen embryo transfer(FET). Several observational studies have been published, but so far with conflicting results.

METHODS

A systematic review and meta-analysis was conducted according to PRISMA guidelines. Pubmed, Embase, Cochrane Library, Clinicaltrails.gov and Web of Science databases were searched based on established search strategy from inception through January 2021.

RESULTS

Twelve studies were eligible. In women following FET, high BMI (BMI ≥ 23 kg/m²) was associated with an impaired live birth rate (LBR, OR: 0.89, 95% CI: 0.82-0.96, P = 0.002), but wasn't associated with the implantation rate or the clinical pregnancy rate. Subgroup analysis revealed higher LBR for women didn't complicated by polycystic ovary syndrome (PCOS, OR: 0.96, 95% CI: 0.85-1.08, P = 0.46) and women with blastocyst transferred (OR: 0.89, 95% CI: 0.68-1.16, P = 0.40). LBR did not differ between the low BMI group (BMI < 18.5 kg/m²) and the normal weight group.

CONCLUSIONS

Our study showed that high BMI in women is negatively associated with LBR in FET cycles, whereas low BMI isn't. The results of subgroup analysis implied a need for women with a high BMI to get individualized weight management and treatment. Further evidence is still required to optimize preconception health and develop Nutritional and exercise guidelines.