Objective
To determine the likely risk factors, such as smoking and drinking habits, and occupational groups, for infertility in a group of infertile men with no known cause, compared with a group of ...fertile men; and to examine the effects of the semen parameters, such as volume, density, motility, viability and normal morphology, on fertility.
Design
A case‐control study.
Setting
The department of obstetric and gynaecology of a tertiary general hospital.
Participants
Six hundred and forty consecutive male partners of couples trying to conceive were recruited from an infertility clinic. Of these, the cases comprised 218 men who had no known cause for their infertility. Two hundred and forty men whose wives were pregnant at the time of the study were recruited as controls.
Results
The semen parameters (e.g. density, total sperm counts, motility, viability and normal morphology) of all cases were significantly poorer than that of the controls. The risk of infertility is associated with smoking (crude OR 2.82, 95% CI 1.93–4.13; adjusted OR 2.96; 95% CI 1.98–4.42). Technicians (adjusted OR 2.81; 95% CI 1.51–4.24) and professional, senior officials and managers were also at a greater risk of infertility (adjusted OR 2.36; 95% CI 1.26–4.40), compared with service and clerical workers. The significant factors predicting infertility were smoking, density of sperm, and viability of sperm. Smoking increased the odds of being infertile. Higher sperm counts and larger percentage of viable sperm decrease the odds of infertility. Based on the multiple logistic regression model, the odds ratio for infertility = 94.70 × 2.88smoking× 0.29logdensity× 0.95viability.
Conclusion
Smoking, density of sperm and the viability of sperm are significant predictors for infertility among men.
The aim of the study was to determine whether there were significant `seasonal' variations in the rhythm of sperm parameters (i.e. semen volume and sperm density) of men who reside in the tropics. A ...total of 7656 semen analysis results from the department of obstetrics and gynaecology of a tertiary general hospital was analysed. These samples were obtained as part of an initial screening for male partners of couples with problems trying to conceive who were attending a fertility clinic from 1991 to 1995. The subjects' mean semen volume and sperm density of 2.9 ml and 26.9×106/ml respectively were within the World Health Organization reference values. There were no significant month-to-month variations in the adjusted (for age of subject, year of test and technologist who performed the analysis by analysis of co-variance, ANCOVA) mean semen volume and sperm density over the 5 year period. Variations in semen volume and density observed in the temperate climates are not seen in this study, which was conducted in subjects staying in the tropics. This observation may be related to relative constant temperature and hours of light exposure among men who reside in the tropics. As this study is, so far, published data from only one country, Singapore, it may not truly reflect the actual situation for individuals who are residing in the tropics.
This paper presents a practical and simple CPW broadside coupled-line balun with multi-layers profile microstrip line and broadside coupling structure to enhance the coupled coefficient and balanced ...output bandwidth. Designed broadside CPW coupled-line balun design with a symmetric quarter wavelength coupled-line is developed to increase wider bandwidth efficiency and the return loss is better than the traditional planar marchaned coupled-lines balun. The structure of the designed balun is fairly simple, practical and easily fabricated. The measured results show good agreements with those analyses data.
This paper describes a harmonic tuning for 1-D microstrip PBG transmission line. ABCD matrix modeling for a periodic defect PBG structure on microstrip is determined. Microstrip PBG structure with ...wide stopband characteristic for broadband harmonic rejection tuning has been experimentally verified. Method of moment is applied to simulate the fields and currents distribution of the design. The results of full wave electromagnetic analyses are in good agreement with those experimental data. An optimal structure of the ID PBG microstrip structure is determined.
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