Reproductive Hazards Still Persist in the Microelectronics Industry: Increased Risk of Spontaneous Abortion and Menstrual Aberration among Female Workers in the Microelectronics Industry in South Korea

Socioeconomic Factors and Abortive Outcomes of Clinical Pregnancy After Embryo Transfer in the Setting of Universal Health Insurance Coverage of IVF

BACKGROUND

In vitro fertilization-embryo transfer (IVF-ET), an expensive option for infertile couples, started to be fully covered by the National Health Insurance (NHI) from October 2017 in South Korea. We investigated the association between woman's socioeconomic status (SES) and abortive outcomes in pregnancies after IVF-ET in the setting of universal coverage of the treatment.

METHODS

Using the NHI database in South Korea, we conducted a retrospective cohort study of all women who achieved clinical pregnancy after ET between October 2017 and February 2019. A total of 44,038 clinical pregnancy episodes of 29,847 women who underwent ET were analyzed. We used employment status, income in percentiles, and living in the Seoul capital area as indicators of SES. Relative risks (RRs) for abortive pregnancy outcomes were calculated for each socioeconomic stratum, using log-binomial regression models included woman's age, body mass index, fasting blood glucose, fresh ET, month of ET, and history of smoking.

RESULTS

While most pregnancy outcomes were live births (n = 30,783, 69.9%), 11,215 (25.5%) cycles ended with abortion or early pregnancy loss, 1,779 (4.0%) cycles were ectopic pregnancy, 45 (0.1%) were coded as molar pregnancy, and 224 (0.5%) were fetal death in utero or stillbirth. The risk of overall abortive outcomes was higher when a woman was unemployed (adjusted RR, 1.08; 95% confidence interval [CI], 1.05-1.11) or living in a non-Seoul capital area (1.11; 95% CI, 1.08-1.14). The association between relative income level and abortive outcomes was close to null. Living outside Seoul capital area was associated with the greater risk of abortive outcomes especially in younger women.

CONCLUSION

Unemployment and living in non-capital areas were associated with a higher risk of abortive outcomes among pregnancies after ET, even in the setting of universal coverage of IVF-ET. This suggests potential impact of socioeconomic position on the IVF-ET pregnancy.

Risk of adverse pregnancy outcomes by maternal occupational status: A national population-based study in South Korea

OBJECTIVE

This study examined the association between maternal occupational status and adverse pregnancy outcomes in the general South Korean population.

METHODS

We analyzed 1 825 845 employed and non-employed women with a diagnostic code for pregnancy in the National Health Insurance Service (NHIS) database (2010-2019) of South Korea. Based on their employment status and type of occupation, we calculated risk ratios for three adverse outcomes: early abortive outcomes (miscarriage, ectopic pregnancy, and molar pregnancy), stillbirth, and no live birth (diagnosis of pregnancy with no record of live birth thereafter, which include early abortive outcomes and stillbirth) with adjusting for covariates.

RESULTS

Overall, 18.0%, 0.7%, and 39.8% ended in early abortive outcomes, stillbirths, and no live births, respectively. The risk of early abortive outcomes and stillbirths was higher in non-employed women than in employed women, while no live births were more frequent in employed women. Those in the health and social work industry showed the highest risk of no live births. Manufacturing jobs (1.030, 95% CI: 1.013, 1.047) and health/social work (1.029, 95% CI: 1.012, 1.046) were associated with an increased risk of early abortive outcomes compared with financial and insurance jobs. Consistently higher risks of no live births were observed in the manufacturing, wholesale/retail trade, education, health/social work, and public/social/personal service occupation.

CONCLUSION

Employment during pregnancy and several occupation types were associated with a higher risk of pregnancy loss. Additional research using detailed job activity data is needed to determine specific occupational causes of adverse pregnancy outcomes.

Semiconductor Work and Adverse Pregnancy Outcomes Associated with Male Workers: A Retrospective Cohort Study

OBJECTIVES

A hazardous work environment in semiconductor factories is a threat to the workers' health. Semiconductor manufacturing characteristically requires young workers, and reproductive toxicity is an important issue. Studies investigating reproductive toxicity among individuals working in the semiconductor manufacturing industry have primarily focused on outcomes in women. Information on the reproductive health of male semiconductor factory workers is limited. This study aimed to evaluate the association between workplace exposures among male workers in a Korean semiconductor company and adverse pregnancy outcomes.

METHODS

Based on the data from the 2015 Semiconductor Health Survey (SHS), which evaluated the workplace exposures, pregnancy outcomes, and general health of 21 969 employees of the semiconductor industry in South Korea, we included 3868 male workers with 7504 pregnancy outcomes identified by self-reports for this retrospective cohort study. Data regarding the pregnancy outcomes, order of pregnancy, and the years of the outcomes were collected via the SHS questionnaire. Adverse pregnancy outcomes were defined as preterm labor, spontaneous abortion, and stillbirth. Workplace exposures were classified as fabrication, assembly, others, lab, and office work (reference group). A generalized estimating equations model including repeated events of individuals and producing relative risk (RR) and 95% confidence interval (CI) was used to estimate the association between workplace exposure and adverse pregnancy outcomes. Analyses were adjusted for work location, spouse's employment in semiconductor production work, educational level, marital status, risky alcohol drinking, smoking status, body mass index, order of pregnancy, and age and year of pregnancy outcome, which were based on a priori decisions.

RESULTS

The adjusted risk for adverse outcomes was higher [RR (95% CI): 1.47 (1.04, 2.07)] among assembly process workers compared with the office workers. Adjusted risks for adverse outcomes among workers in assembly and fabrication, whose spouses also worked in semiconductor production, were 1.60 (95% CI: 1.04, 2.46) and 1.74 (95% CI: 1.18, 2.57) times higher, respectively, compared with the office workers with spouses not working in semiconductor production.

CONCLUSIONS

Based on these findings, semiconductor work might be considered a risk factor for reproductive toxicity among male workers, especially for those whose spouses have the same job.

Design of a Compliant Mechanism Based Four-Stage Amplification Piezoelectric-Driven Asymmetric Microgripper

The existing symmetrical microgrippers have larger output displacements compared with the asymmetrical counterparts. However, the two jaws of a symmetrical microgripper are less unlikely to offer the same forces on the two sides of a grasped micro-object due to the manufacture and assembly errors. Therefore, this paper proposes a new asymmetric microgripper to obtain stable output force of the gripper. Compared with symmetrical microgrippers, asymmetrical microgrippers usually have smaller output displacements. In order to increase the output displacement, a compliant mechanism with four stage amplification is employed to design the asymmetric microgripper. Consequently, the proposed asymmetrical microgripper possesses the advantages of both the stable output force of the gripper and large displacement amplification. To begin with, the mechanical model of the microgripper is established in this paper. The relationship between the driving force and the output displacement of the microgripper is then derived, followed by the static characteristics’ analysis of the microgripper. Furthermore, finite element analysis (FEA) of the microgripper is also performed, and the mechanical structure of the microgripper is optimized based on the FEA simulations. Lastly, experimental tests are carried out, with a 5.28% difference from the FEA results and an 8.8% difference from the theoretical results. The results from theoretical calculation, FEA simulations, and experimental tests verify that the displacement amplification ratio and the maximum gripping displacement of the microgripper are up to 31.6 and 632 μm, respectively.

Semiconductor Work and the Risk of Spontaneous Abortion: A Systematic Review and Meta-Analysis

(1) Background: In the semiconductor industry, female workers were identified as having an increased risk of spontaneous abortion (SA). To date, the association between semiconductor work and SA is controversial. We aimed to assess the association between semiconductor work and specific processes and SA, in the semiconductor industry. (2) Methods: A literature search was conducted using databases such as PubMed, Embase, Cochrane library, and other core databases, from the date of inception of these databases to 31 July 2019. Studies that identified SA risk in female workers in the semiconductor industry were included. (3) Results: We identified 529 studies, of which six studies were included in the meta-analysis. During 1980–1993, the risk of SA in fabrication (Fab) workers was significantly higher than non-Fab workers (RR, 1.29; 95% CI, 1.05–1.57). Photolithography workers had a higher SA risk than non-process and office workers (RR, 1.41; 95% CI, 1.13–1.77). (4) Conclusion: Meta-analysis indicates a statistically significant association between Fab-work and SA. Specific process and chemical exposure meta-analyses need to be interpreted carefully considering bias. Because of the rapid change in the semiconductor industry, it is necessary to conduct an elaborate cohort study taking into consideration the current working environment.

The relationship between spontaneous abortion and female workers in the semiconductor industry

Background

This study investigated the relationship between job type and the risk for spontaneous abortion to assess the reproductive toxicity of female workers in the semiconductor industry.

Methods

A questionnaire survey was administered to current female workers of two semiconductor manufacturing plants in Korea. We included female workers who became pregnant at least 6 months after the start of their employment with the company. The pregnancy outcomes of 2,242 female workers who experienced 4,037 pregnancies were investigated. Personnel records were used to assign the subjects to one of three groups: fabrication process workers, packaging process workers, and clerical workers. To adjust for within-person correlations between pregnancies, a generalized estimating equation was used. The logistic regression analysis was limited to the first pregnancy after joining the company to satisfy the assumption of independence among pregnancies. Moreover, we stratified the analysis by time period (pregnancy in the years prior to 2008 vs. after 2009) to reflect differences in occupational exposure based on semiconductor production periods.

Results

The risk for spontaneous abortion in female semiconductor workers was not significantly higher for fabrication and packaging process workers than for clerical workers. However, when we stratified by time period, the odds ratio for spontaneous abortion was significantly higher for packaging process workers who became pregnant prior to 2008 when compared with clerical workers (odds ratio: 2.21; 95% confidence interval: 1.01–4.81).

Conclusions

When examining the pregnancies of female semiconductor workers that occurred prior to 2008, packaging process workers showed a significantly higher risk for spontaneous abortions than did clerical workers. The two semiconductor production periods in our study (prior to 2008 vs. after 2009) had different automated processes, chemical exposure levels, and working environments. Thus, the conditions prior to 2008 may have increased the risk for spontaneous abortions in packaging process workers in the semiconductor industry.

Electronic supplementary material

The online version of this article (10.1186/s40557-017-0204-x) contains supplementary material, which is available to authorized users.

Prevalence of abortion and adverse pregnancy outcomes among working women in Korea: A cross-sectional study

OBJECTIVES

To investigate incidence and distribution of major adverse reproductive health problems related to various kinds of industries in Korea and to compare risks for major reproductive outcomes to assess maternal health in working and non-working women.

METHODS

We requested claim data from the Korean National Health Insurance. We defined reference groups as (1) non-working women and (2) workers in the education field. Women working in each industry were compared with reference groups regarding rates of miscarriage, threatened abortion, preterm labor, and intrauterine growth restriction. Logistic regression was used for multivariate analysis, and age and income adjustment was performed.

RESULTS

The percentages of all adverse obstetric outcomes were higher in working women than in non-working women. Working women had higher and statistically significant adjusted odds ratios (ORs) for miscarriage in 18 of the 21 industries. The age and income-adjusted OR for miscarriage for all working women was 1.26 (95% confidence interval, 1.23-1.28). Business facilities management and business support services, manufacturing, human health and social work activities, wholesale and retail trade, and professional, scientific, and technical activities were major industries with higher adjusted ORs for adverse obstetric outcomes.

CONCLUSIONS

We confirmed that compared to non-working women, working women have a higher risk for adverse pregnancy outcomes. Thus, adverse pregnancy outcomes such as threatened abortion, preterm labor, and intrauterine growth restriction may be associated with working status. This exploratory study identified several industries where in-depth studies are required in future to improve occupational safety in women of reproductive age.