Air quality in the assisted reproduction laboratory: a mini-review

Mixed effects of ambient air pollutants on oocyte-related outcomes: A novel insight from women undergoing assisted reproductive technology

Air pollution is widely acknowledged as a significant risk factor for human health, especially reproductive health. Nevertheless, many studies have disregarded the potentially mixed effects of air pollutants on reproductive outcomes. We performed a retrospective cohort study involving 8048 women with 9445 cycles undergoing In Vitro Fertilization (IVF) and Intracytoplasmic Sperm Injection (ICSI) in China, from 2017 to 2021. A land-use random forest model was applied to estimate daily residential exposure to air pollutants, including sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particulate matter (PM2.5). Individual and joint associations between air pollutants and oocyte-related outcomes of ART were evaluated. In 90 days prior to oocyte pick-up to oocyte pick-up (period A), NO2, O3 and CO was negatively associated with total oocyte yield. In the 90 days prior to oocyte pick-up to start of gonadotropin medication (Gn start, period B), there was a negative dose-dependent association of exposure to five air pollutants with total oocyte yield and mature oocyte yield. In Qgcomp analysis, increasing the multiple air pollutants mixtures by one quartile was related to reducing the number of oocyte pick-ups by -2.00 % (95 %CI: -2.78 %, -1.22 %) in period A, -2.62 % (95 %CI: -3.40 %, -1.84 %) in period B, and -0.98 % (95 %CI: -1.75 %, -0.21 %) in period C. During period B, a 1-unit increase in the WQS index of multiple air pollutants exposure was associated with fewer number of total oocyte (-1.27 %, 95 %CI: -2.16 %, -0.36 %) and mature oocyte (-1.42 %, 95 %CI: -2.41 %, -0.43 %). O3 and NO2 were major contributors with adverse effects on the mixed associations. Additionally, period B appears to be the susceptible window. Our study implies that exposure to air pollution adversely affects oocyte-related outcomes, which raises concerns about the potential adverse impact of air pollution on women's reproductive health.

Comparison of pregnancy outcomes between 4th day morula and 5th day blastocyst after embryo transfer: a retrospective cohort study

BACKGROUND

This study was designed to evaluate pregnancy outcomes between morulae transferred on day 4 (D4) and blastocysts transferred on day 5 (D5).

METHODS

From September 2017 to September 2020, 1963 fresh transfer cycles underwent early follicular phase extra-long protocol for assisted conception in our fertility center were divided into D4 (324 cases) and D5 (1639 cases) groups, and the general situation and other differences of patients in both groups were compared. To compare the differences in pregnancy outcomes, the D4 and D5 groups were further divided into groups A and B based on single and double embryo transfers. Furthermore, the cohort was divided into two groups: those with live births (1116 cases) and those without (847 cases), enabling a deeper evaluation of the effects of D4 or D5 transplantation on assisted reproductive outcomes.

RESULTS

In single embryo transfer, there was no significant difference between groups D4A and D5A (P > 0.05). In double embryo transfer, group D4B had a lower newborn birthweight and a larger proportion of low birthweight infants (P < 0.05). The preterm delivery rate, twin delivery rate, cesarean delivery rate, and percentage of low birthweight infants were lower in the D5A group than in the D5B group (P < 0.05). Analysis of factors influencing live birth outcomes further confirmed the absence of a significant difference between D4 and D5 transplantation in achieving live birth (P > 0.05).

CONCLUSION

When factors such as working life and hospital holidays are being considered, D4 morula transfer may be a good alternative to D5 blastocyst transfer. Given the in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) success rate and risk of twin pregnancy, D4 morula transfer requires an adapted decision between single and double embryo transfer, although a single blastocyst transfer is recommended for the D5 transfer in order to decrease the twin pregnancy rate. In addition, age, endometrial thickness and other factors need to be taken into account to personalize the IVF program and optimize pregnancy outcomes.

Unhealthy air quality secondary to wildfires is associated with lower blastocyst yield

OBJECTIVE

To study the impact of unhealthy air quality from the 2020 Oregon wildfires on outcomes for patients undergoing in vitro fertilization (IVF) treatment.

DESIGN

A retrospective cohort study.

SETTING

A university-based fertility clinic.

PATIENTS

Subjects were undergoing IVF treatment from the 6 weeks preceding the wildfires through a 10-day exposure period. Cohorts were classified on the basis of whether subjects experienced patient and/or laboratory exposure to unhealthy air quality. Patient exposure was defined as at least 4 days of ovarian stimulation overlapping with the exposure, and laboratory exposure was defined as at least 2 days of IVF treatment and embryogenesis overlapping with the exposure. The unexposed cohort consisted of remaining subjects without defined exposure, with cycles in the 6 weeks preceding the wildfires. As some subjects had dual exposure and appeared in both patient and laboratory exposure cohorts, each cohort was separately compared with the unexposed control cohort.

INTERVENTION

A 10-day period of unhealthy air quality caused by smoke plumes from a wildfire event.

MAIN OUTCOME MEASURES

The primary outcome was the blastulation rate. Secondary outcomes included fertilization rate, number of blastocysts obtained, and cycles with no blastocysts frozen or transferred.

RESULTS

Sixty-nine subjects underwent ovarian stimulation and IVF treatment during the 6 weeks preceding the wildfires through the 10-day period of unhealthy air quality. Of these, 15 patients were in the laboratory exposure cohort, 16 were in the patient exposure cohort, and 44 were unexposed. Six subjects appeared in both laboratory and patient exposure cohorts. Although neither exposure cohort had significantly decreased blastulation rate compared with the unexposed, the median number of blastocysts obtained was significantly lower in the laboratory exposure cohort than the unexposed group (2 [range 0-14] vs. 4.5 [range 0-21], respectively). The laboratory exposure cohort had significantly more cycles with no blastocysts obtained (3/15 [20%] vs. 1/44 [2%]). There were no significant differences in IVF treatment outcomes between patient exposure and unexposed cohorts. These findings persisted after controlling for age. There were no significant differences in pregnancy outcomes observed after embryo transfer between the exposure group and the unexposed group.

CONCLUSION

For a cohort of patients undergoing IVF treatment, an acute episode of outside wildfire smoke exposure during fertilization and embryogenesis was associated with decreased blastocyst yield.

The relationship between microbial contaminations of embryo transfer catheters with pregnancy outcome after embryo transfer

Background

Different stages of assisted reproductive technologies are susceptible to contamination by various microorganisms.

Objective

The aim of the study was to investigate the relationship between microbial contamination of embryo transfer catheters and the pregnancy outcome after embryo transfer.

Methods

This cohort study was conducted on 60 patients candied for in vitro fertilization and embryo transfer cycles from 2021 to 2022. All embryos were transferred using a sterile syringe. The catheter contamination was checked by the microbial culture method, and in the case of microbial culture that were negative, polymerase chain reaction was done to confirm the result. The data analyzed using STATA 17 to determine the impact of catheter contamination on the clinical pregnancy rate.

Results

The average age of peoples whose microbial culture was positive was lower than that of people whose microbial culture was negative (P<0.05). Also the results showed that people who live in villages have more positive microbial cultures than people who live in cities (P<0.05). Also there is no difference between the number of successful implantations and the pregnancy outcome between people whose microbial culture results were positive or negative.

Conclusion

The results of the current study showed that the contamination of the embryo transfer catheter with microorganisms under our investigation did not affect the pregnancy outcome.

Analysis of the clinical outcomes of microbial contamination caused by environmental contamination of the embryology laboratory during IVF-ET treatment cycles

BACKGROUND

Bacterial contamination may cause loss of or damage to cultured oocytes or embryos, resulting in the lack of transplantable embryos during IVF embryo culture. However, there are few reports about IVF embryo contamination caused by embryology laboratories. In this work, we evaluated clinical pregnancy outcomes and the risk of maternal and infant complications after embryo contamination caused by environmental pollution during IVF.

METHODS

The authors retrospectively analyzed 2490 IVF-ET ovulation induction therapy cycles in the Reproductive Center of Yichang Central People's Hospital from January 2015 to May 2022. According to the presence or absence of embryo culture medium contamination, the two groups were divided into an embryo contamination cycle and a nonembryo contamination cycle. The primary outcome parameters were the characteristics and progress of embryo culture medium contamination. Embryo laboratory outcomes, pregnancy outcomes, and maternal and infant complications were secondary outcome parameters.

RESULTS

One case of embryo contamination originated from semen contamination. The remaining 15 cases involved environmental contamination outbreaks in embryo culture chambers, caused by Staphylococcus pasteuri. Compared with conventional uncontaminated IVF cycles, the 15 cases of contaminated embryo cycles showed no significant difference in embryo laboratory outcomes, pregnancy outcomes, or maternal and infant complications except for a slightly higher rate of fetal growth retardation. Ultimately, 11 live-born infants were successfully delivered, of which 2 were premature. The remaining 4 patients did not become pregnant after 1-2 transfers due to a lack of transferable embryos.

CONCLUSION

When the embryo culture medium is contaminated due to the environmental contamination of the IVF culture room, it is feasible to perform daily rapid rinsing of the culture medium and avoid blastocyst culture as remedial treatment. However, the long-term impact on offspring needs further prospective research.

Association between ambient air pollution and pregnancy outcomes in patients undergoing in vitro fertilization in Shanghai, China: A retrospective cohort study

BACKGROUND

The effects of ambient air pollutants on adverse pregnancy outcomes have been reported. However, studies about air pollutants exposure and pregnancy outcomes in patients undergoing IVF were limited and inconclusive. To date Shanghai has been the only city in China to implement a compulsory single embryo transfer policy for all patients undergoing their first embryo transfer procedure effective from January 2019. We aimed to investigate the associations between exposure to ambient air pollutants and biochemical pregnancy and live births, and to identify potential vulnerability characteristics of patients undergoing IVF in Shanghai, China.

METHODS

A retrospective cohort study was conducted on 2766 infertile patients aged ≤ 45 years who underwent first fresh or frozen-thawed cleavage stage embryo transfer in the Shanghai First Maternity and Infant Hospital during April 2016 and December 2019. Daily average ambient levels of six air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO and O₃ max-8h) were obtained from fixed air monitors located in closest proximity to patients' residences. The cumulative average level was calculated during three different exposure periods (period1: three months before oocyte retrieval to serum hCG test; period 2: from serum hCG test to live birth outcome; period 3: from three months before oocyte retrieval to live birth). Multiple logistic regression model was performed to investigate associations between exposure to ambient air pollutants and pregnancy outcomes. Stratified analyses were conducted to explore the potential effects modifier.

RESULTS

The biochemical pregnancy rate and live birth rate were 54.2% and 36.4%, respectively. The ambient NO₂ exposure was significantly associated with a 14% lower pregnancy rate during period 1 (aOR = 0.86, 95%CI: 0.75-0.99). The ambient PM₁₀ was related to significantly increased risk of lowering live birth rate among the patients during period 3 [aOR = 0.88(0.79-0.99)]. Stratified analysis showed that ambient PM₁₀ was also significantly associated with a reduced pregnancy rate (aOR = 0.82, 95% CI: 0.69-0.97) in patients who underwent single embryo transfer during period 1. Subjects who underwent single embryo transfer also had a decreased likelihood of a live birth when exposed to ambient SO₂ and O₃ during period 3 [aOR = 0.74(0.57-0.95), and 0.92 (0.83-0.98), respectively]. Moreover, O₃ exposure was associated with decreased live birth rates in patients living in non-urban areas. Sensitivity analyses indicated robust negative association between PM₁₀ exposure and live birth outcomes.

CONCLUSIONS

Our study suggested that exposure to ambient air pollutants, in particular NO₂ and PM₁₀, was associated with an increased risk of lower rates of pregnancy and live birth respectively in patients undergoing IVF. Stratified analyses indicated that ambient SO₂ and O₃ levels were related to adverse pregnancy outcomes in some subgroups of IVF patients in this study. Notably, patients who underwent single embryo transfer were more susceptible to ambient air pollution exposure. Thus, prospective cohort studies are needed to investigate the underlying mechanisms and the susceptibility windows for women undergoing IVF treatment.

Air quality in the clinical embryology laboratory: a mini-review

The scope of the clinical embryology laboratory has expanded over recent years. It now includes conventional in vitro fertilization (IVF) techniques and complex and time-demanding procedures like blastocyst culture, processing of surgically retrieved sperm, and trophectoderm biopsy for preimplantation genetic testing. These procedures require a stable culture environment in which ambient air quality might play a critical role. The existing data indicate that both particulate matter and chemical pollution adversely affect IVF results, with low levels for better outcomes. As a result, IVF clinics have invested in air cleaning technologies with variable efficiency to remove particulates and volatile organic compounds. However, specific regulatory frameworks mandating air quality control are limited, as are evidence-based guidelines for the best air quality control practices in the embryology laboratory. In this review, we describe the principles and existing solutions for improving air quality and summarize the clinical evidence concerning air quality control in the embryology laboratory. In addition, we discuss the gaps in knowledge that could guide future research to improve clinical outcomes.

Necessity is the mother of invention and the evolutionary force driving the success of in vitro fertilization

During the last few decades, millions of healthy children have been born with the aid of in vitro fertilization (IVF). This success belies the fact that IVF treatment is comprised of a complex series of interventions starting with a customized control ovarian stimulation protocol. This is followed by the induction of oocyte maturation, the retrieval of mature oocytes and in vitro fertilization, which often involves the microinjection of a single sperm into the oocyte. After fertilization, the resulting embryos are cultured for up to 7 days. The best embryos are transferred into the uterus where the embryo implants and hopefully develops into a healthy child. However, frequently the best embryos are biopsied and frozen. The biopsied cells are analyzed to identify those embryos without chromosomal abnormalities. These embryos are eventually thawed and transferred with pregnancy rates as good if not better than embryos that are not biopsied and transferred in a fresh cycle. Thus, IVF treatment requires the coordinated efforts of physicians, nurses, molecular biologists and embryologists to conduct each of these multifaceted phases in a seamless and flawless manner. Even though complex, IVF treatment may seem routine today, but it was not always the case. In this review the evolution of human IVF is presented as a series of innovations that resolved a technical hurdle in one component of IVF while creating challenges that eventually lead to the next major advancement. This step-by-step evolution in the treatment of human infertility is recounted in this review.

Ambient air pollution and in vitro fertilization treatment outcomes

STUDY QUESTION

Is air pollution associated with IVF treatment outcomes in the USA?

SUMMARY ANSWER

We did not find clear evidence of a meaningful association between reproductive outcomes and average daily concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) and ozone (O3).

WHAT IS KNOWN ALREADY

Maternal exposure to air pollution such as PM2.5, nitrogen oxides, carbon monoxide or O3 may increase risks for adverse perinatal outcomes. Findings from the few studies using data from IVF populations to investigate associations between specific pollutants and treatment outcomes are inconclusive.

STUDY DESIGN, SIZE AND DURATION

Retrospective cohort study of 253 528 non-cancelled fresh, autologous IVF cycles including 230 243 fresh, autologous IVF cycles with a transfer of ≥1 embryo was performed between 2010 and 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We linked 2010-2012 National ART Surveillance System data for fresh, autologous IVF cycles with the ambient air pollution data generated using a Bayesian fusion model available through the Centers for Disease Control and Prevention's Environmental Public Health Tracking Network. We calculated county-level average daily PM2.5 and O3 concentrations for three time periods: cycle start to oocyte retrieval (T1), oocyte retrieval to embryo transfer (T2) and embryo transfer +14 days (T3). Multivariable predicted marginal proportions from logistic and log-linear regression models were used to estimate adjusted risk ratios (aRR) and 95% CI for the association between reproductive outcomes (implantation rate, pregnancy and live birth) and interquartile increases in PM2.5 and O3. The multipollutant models were also adjusted for patients and treatment characteristics and accounted for clustering by clinic and county of residence.

MAIN RESULTS AND THE ROLE OF CHANCE

For all exposure periods, O3 was weakly positively associated with implantation (aRR 1.01, 95% CI 1.001-1.02 for T1; aRR 1.01, 95% CI 1.001-1.02 for T2 and aRR 1.01, 95% CI 1.001-1.02 for T3) and live birth (aRR 1.01, 95% CI 1.002-1.02 for T1; aRR 1.01, 95% CI 1.004-1.02 for T2 and aRR 1.02, 95% CI 1.004-1.03 for T3). PM2.5 was not associated with any of the reproductive outcomes assessed.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study is the use of aggregated air pollution data as proxies for individual exposure. The weak positive associations found in this study might be related to confounding by factors that we were unable to assess and may not reflect clinically meaningful differences.

WIDER IMPLICATIONS OF THE FINDINGS

More research is needed to assess the impact of air pollution on reproductive function.

STUDY FUNDING/COMPETING INTEREST(S)

None.

Practical Considerations in Providing Preimplantation Genetic Testing for Aneuploidies (PGT-A)

Preimplantation genetic testing for aneuploidies (PGT-A) has been controversial in its application to improve reproductive success, reduce time-to-pregnancy, and serve the intention-to-treat. Nevertheless, many in vitro fertilization (IVF) units have already introduced the service for one reason or another. Given PGT-A is not a stand-alone technique but a clinical service involving several disciplines, this mini review discussed the factors that can influence success rates when PGT-A is applied and highlighted practical issues encountered by clinicians, embryology, and genetics laboratories involved in the provision of PGT-A service.

An Internet of Things-Based Environmental Quality Management System to Supervise the Indoor Laboratory Conditions

Indoor air quality (IAQ) is not only a determinant of occupational health but also influences all indoor human behaviours. In most university establishments, laboratories are also used as classrooms. On one hand, indoor environment quality (IEQ) conditions supervision in laboratories is relevant for experimental activities. On the other hand, it is also crucial to provide a healthy and productive workplace for learning activities. The proliferation of cost-effective sensors and microcontrollers along with the Internet of Things (IoT) architectures enhancements, enables the development of automatic solutions to supervise the Laboratory Environmental Conditions (LEC). This paper aims to present a real-time IEQ-laboratory data collection system-based IoT architecture named iAQ Plus (iAQ+). The iAQ+ incorporates an integrated Web management system along with a smartphone application to provide a historical analysis of the LEC. The iAQ+ collects IAQ index, temperature, relative humidity and barometric pressure. The results obtained are promising, representing a meaningful contribution for IEQ supervision solutions based on IoT. iAQ+ supports push notifications to alert people in a timely way for enhanced living environments and occupational health, as well as a work mode feature, so the user can configure setpoints for laboratory mode and schoolroom mode. Using the iAQ+, it is possible to provide an integrated management of data information of the spatio-temporal variations of LEC parameters which are particularly significant not only for enhanced living environments but also for laboratory experiments.

[Impact of air quality on practices and results in the IVF laboratory]

The concept of Air Quality often refers to particulate and microbiological contamination of ambiant air. European Directive 2006/86/CE encompass the IVF process and specify a class A air quality for manipulation of tissue and cells, in a class D environment (A over D rule). Recognizing the paramount importance of ensuring the highest microbiological and particulate safety in the IVF laboratory, it is equally important to take into account practicability issues and the financial burden of these recommendations, as well as the utter need to protect gametes and embryo viability during their IVF journey. The usefulness of such stringent recommendations may also be questionned given the absence of published cases of airborne contaminations and related patients infections after embryo transfer. The European directive stems from pharmaceutical standards and were not specifically designed for human IVF. Gametes and embryos are indeed extremely sensitive to physical and chemical stress and require strict temperature, osmolarity and pH control, as well as an absence of chemical contamination during manipulation and culture. These conditions are hardly obtained when using laminar flow hoods. Following concerns raised by many experts in the field, exceptions to the A over D rule were added in the 2006/86/CE Directives. This narrative review discusses all these aspects in a critical way and compare scientific and legal requirements applying to IVF practices in different regions of the world.

Cairo consensus on the IVF laboratory environment and air quality: report of an expert meeting

This proceedings report presents the outcomes from an international Expert Meeting to establish a consensus on the recommended technical and operational requirements for air quality within modern assisted reproduction technology (ART) laboratories. Topics considered included design and construction of the facility, as well as its heating, ventilation and air conditioning system; control of particulates, micro-organisms (bacteria, fungi and viruses) and volatile organic compounds (VOCs) within critical areas; safe cleaning practices; operational practices to optimize air quality while minimizing physicochemical risks to gametes and embryos (temperature control versus air flow); and appropriate infection-control practices that minimize exposure to VOC. More than 50 consensus points were established under the general headings of assessing site suitability, basic design criteria for new construction, and laboratory commissioning and ongoing VOC management. These consensus points should be considered as aspirational benchmarks for existing ART laboratories, and as guidelines for the construction of new ART laboratories.

Volatile organic compounds and good laboratory practices in the in vitro fertilization laboratory: the important parameters for successful outcome in extended culture

PURPOSE

This study aims to describe the role of implementing good laboratory practices to improve in vitro fertilization (IVF) outcomes which are of great interest for practitioners dealing with infertility.

METHODS

Certain modifications were introduced in May 2015 in our IVF laboratory like high-efficiency particulate air CODA system, steel furniture instead of wooden, use of new disinfectants like oosafe, and restriction of personnel entry along with avoidance of cosmetics like perfume to improve pregnancy rates. Volatile organic compound (VOC) meter reading was monitored at two time points and five different places in the laboratory to compare the embryonic development parameters before (group A: July 2014-April 2015) and after (group B: July 2015-April 2016) remodeling.

RESULTS

The IVF outcomes from 1036 cycles were associated in this study. Reduction in VOC meter readings, enhanced air quality, improvement in blastocyst formation rate, implantation, and clinical pregnancy rate were observed in the laboratory after implementation of new facilities. Results illustrated that the attention must be focused on potential hazards which expose laboratories to elevated VOC levels. Blastocyst formation rate increased around 18%. Implantation rate, clinical pregnancy rate, and live birth rate increased by around 11, 10, and 8%, respectively.

CONCLUSION

In conclusion, with proper engineering and material selection, we have been able to reduce chemical contamination and adverse effects on culture with optimized IVF results.

SUPPORT

None.

How do laboratory embryo transfer techniques affect IVF outcomes? A review of current literature

Over the last few years, many studies have focused on embryo selection methods, whereas little attention has been given to the standardization of the procedure of embryo transfer. In this review, several parameters of the embryo transfer procedure are examined, such as the: (i) culture medium volume and loading technique; (ii) syringe and catheters used for embryo transfer; (iii) viscosity and composition of the embryo transfer medium; (iv) environment of embryo culture; (v) timing of embryo transfer; (vi) and standardization of the embryo transfer techniques. The aim of this manuscript is to review these factors and compare the existing embryo transfer techniques and highlight the need for better embryo transfer standardization.