Low BMI associated with Unfavorable intrauterine insemination treatment outcomes

CHINA: BMI is favorably correlated with cumulative intrauterine insemination (IUI) treatment outcomes in women with a BMI under 30 kg/m2, according to a study published in the Journal of Assisted Reproduction and Genetics.

Particularly, compared to normal weight and overweight women, underweight women may have a reduced likelihood of pregnancy.

Approximately 10-15% of couples, or more, struggle with infertility. Due to its ease and low cost, intrauterine insemination (IUI) is undoubtedly the therapy of choice for couples whose infertility is due to mild or unexplained male factor infertility.

Age, infertility diagnosis, body mass index (BMI), and semen quality are some of the variables that have been connected to the likelihood of conception after IUI cycles. Among them, BMI has consistently been shown to be a poor predictor of success with assisted reproduction.

Notably, numerous studies found that BMI was favorably correlated with conception after IUI, suggesting that being underweight rather than being obese has negative effects.

The authors of the current study set out to determine if body mass index (BMI) and pregnancy outcomes in women undergoing intrauterine insemination (IUI) treatment are related.

As per BMI, the study included 6407 women who underwent 13,745 IUI cycles. The correlation between BMI and the total number of cumulative live births throughout numerous IUI cycles was examined using Cox regression. The analysis of the live birth rate each cycle was conducted using a generalized estimating equation (GEE).

Key findings of the study:

• Underweight women (n = 990) had a reduced cumulative pregnancy and live birth rate compared to normal-weight women (n = 4563), while overweight women (n = 854) had a higher cumulative pregnancy and live birth rate compared to normal-weight women (31.97%, 26.58%).
• The hazard ratio (HR) for attaining a live birth after a maximum of four IUI cycles, adjusted for covariates, was 0.80 (95% CI: 0.67-0.95), contrasting underweight with normal weight.
• Low BMI was also linked to a decreased per-cycle birth rate in the GEE studies after adjusting for cycle-specific factors such ovarian stimulation, endometrial thickness, and follicular diameter (OR 0.79, 95% CI: 0.66-0.95).

According to Jianzhi Ren and team from the Reproductive Medicine Center at the Xiamen University Affiliated Chenggong Hospital, "With growing concerns about the health effects of obesity, numerous authors have simply ignored underweight women or combined them with women with normal BMI."

Nevertheless, the researchers concluded that their data "suggest that while giving advice to patients undergoing IUI treatments, underweight as well as obesity should be considered."

REFERENCE

Zheng, J., Cai, J., Liu, L. et al. Low BMI is associated with poor IUI outcomes: a retrospective study in 13,745 cycles. J Assist Reprod Genet (2022). https://doi.org/10.1007/s10815-022-02658-y