Ovarian Hyperstimulation Syndrome (OHSS) requiring Intensive Care Unit (ICU) admission between 1996-2020 in England, Wales, and Northern Ireland

Association of Long-Term PM2.5 and Its Components Exposure with Ovarian Hyperstimulation Syndrome Risk in Assisted Reproductive Technology Patients

This study investigates the impact of long-term exposure to ambient fine particulate matter (PM2.5) and its components on the risk of ovarian hyper stimulation syndrome (OHSS) in women undergoing assisted reproductive technology (ART). We conducted a retrospective cohort study at a large reproductive medical center in Sichuan Province, China, including 45,703 women undergoing their first ART cycle between January 2018 and May 2024. The overall incidence of OHSS was 1.67%. Exposure to PM2.5 and its components (black carbon [BC], organic matter [OM], sulfate [SO42-], nitrate [NO3-], and ammonium [NH4+]) was estimated based on residential addresses. Exposure windows were defined as three distinct time periods within the year preceding oocyte retrieval: (1) the 3 months immediately before retrieval, (2) months 4 to 12 before retrieval, and (3) the entire 12-month period before retrieval. Poisson regression assessed single-pollutant effects, while quantile g-computation evaluated joint effects. Distributed lag nonlinear models (DLNM) identified critical exposure windows. Results indicated that exposure to each pollutant was significantly associated with increased OHSS risk. Combined exposure over the previous year increased OHSS risk (RR: 1.22, 95% CI: 1.13-1.32), with BC and NH4+ contributing most to 1 year effects, and SO42- dominating the 3 months before retrieval. DLNM identified the first 6 months before oocyte retrieval as a susceptible period, and stratified analysis showed that younger women (<35 years) were more sensitive to exposure. These findings underscore the need for policies to reduce air pollution and safeguard reproductive health.

Expert opinion on refined and extended key performance indicators for individualized ovarian stimulation for assisted reproductive technology

OBJECTIVE

To assess the adequate ovarian follicular development and oocyte recovery between ovarian potential (antral follicle count [AFC]) before the start of ovarian stimulation (OS) and oocyte quantity and quality at oocyte retrieval. A holistic overview of the current key performance indicators (KPIs) was applied to identify the complementary strengths and identify where the current repertoire can be expanded.

DESIGN

Expert opinion.

INTERVENTION

None.

MAIN OUTCOME MEASURES

To formulate a proposal for a refined and expanded repertoire of KPIs for individualized OS for assisted reproductive technology.

RESULTS

The performance and outcomes of OS on ovarian follicular development can be evaluated through the application of defined KPIs. Current KPIs for OS are the ovarian sensitivity index, follicular output rate (FORT), oocyte retrieval rate, and follicle-to-oocyte index (FOI). Notably, there are no specific KPIs dedicated to the assessment of follicular development (i.e., recruitment, selection, growth, and dominance). In light of this, we recommend expanding the current KPIs for OS to include "early FORT" (accounting for the number of follicles measuring ≥10 to 11 mm on day 5/6 of OS relative to AFC) and "modified FORT" (the ratio between the number of follicles measuring ≥12 mm at the time of oocyte maturation triggering and AFC); the extension of oocyte retrieval rate to include two discrete categories at oocyte retrieval-follicles measuring ≥12 mm and ≥16 mm-to ensure that all responsive follicles are accounted for; and FOI to be measured at oocyte maturation triggering and oocyte retrieval ("advanced FOI").

CONCLUSION

Once validated and adopted in clinical practice, we envisage that the proposed expanded KPIs measuring the effect of OS on follicular development (recruitment, selection, growth, and dominance) will increase the understanding of the relationship between ovarian reserve, measured by AFC, and oocyte quantity and quality at oocyte retrieval. This understanding will enable physicians to better evaluate the direct effect of different gonadotropins and doses on ovarian response, leading to a more personalized approach to OS in the context of assisted reproductive technology treatment.

Effect of aromatase inhibitors for preventing ovarian hyperstimulation syndrome in infertile patients undergoing in vitro fertilization: a systematic review and meta-analysis

PURPOSE

To summarize the findings of relevant randomized controlled trials (RCTs) and conduct a meta-analysis to investigate the potential effect of aromatase inhibitors on preventing moderate to severe ovarian hyperstimulation syndrome (OHSS) in infertile women undergoing in vitro fertilization (IVF).

METHODS

We searched for relevant RCTs in electronic databases, including MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov (from inception to August 2023). In addition, we manually searched the related reviews and reference lists of included studies for further relevant studies. We included RCTs where aromatase inhibitors prescribed either during controlled ovarian stimulation (COS) or in early luteal phase. The meta-analysis was performed using RevMan 5.4.1 software. The primary outcome was the incidence of moderate to severe OHSS. A descriptive analysis was conducted in cases where a meta-analysis was not feasible due to heterogeneity or lack of comparable data.

RESULTS

2858 records were retrieved and 12 RCTs were finally included. Letrozole was administered in the treatment group during COS in seven RCTs, whereas in the early luteal phase in five RCTs. Compared with the control group, the risk of moderate to severe OHSS significantly reduced by 55% in the letrozole group (RR 0.45, 95% CI 0.32 to 0.64, I2 = 0%, 5 RCTs, 494 patients). Moreover, serum estradiol (E2) levels on hCG trigger day significantly decreased with the administration of letrozole during COS (MD -847.23, 95% CI -1398.00 to -296.47, I2 = 93%, 5 RCTs, 374 patients). And serum E2 levels on the 4th, 5th and 7th to 10th day after hCG trigger were also significantly lower than those in the control group when letrozole was administered in the early luteal phase.

CONCLUSIONS

Patients with high risk of OHSS probably benefit from letrozole, which has been revealed to reduce the incidence of moderate to severe OHSS by this systematic review. However, the very limited number of participants and the quality of the included studies does not allow to recommend letrozole for the prevention of severe OHSS.