Evaluation of trend in semen analysis for 11 years in subjects attending a fertility clinic in India

Keywords: semen analysis; sperm motility; declining sperm count; male infertility

Abstract

Aim: The data on semen analysis of subjects attending the Fertility Clinic at NIHFW (National Institute of Health and Family Welfare) Munirka, New Delhi for the last 11 years were analyzed to verify the claims and speculations on declining sperm counts in men. Methods: Approximately 10 % of the records every year starting from 1990 to 2000 (numbering 1176 in total) were randomly selected for analysis. Subjects with azoospermia or severe oligozoospermia were excluded from analysis. Results: The average age of the men attending the infertility clinic was 31.2 years. The average semen volume and sperm count were found to be (2.60.1) mL and (60.60.9) 10⁶/mL, respectively. No significant decline in sperm counts was observed in any year during the entire study period. Only 1.8 % of the total number of sperm counts in the random sampling were less then 2010⁶/mL. On the basis of WHO criteria on motility, the total percentage of non-progressive and non-motile sperm in the ejaculate was higher (63 %) as compared to the combined categories of slow and rapid linear progressive. Conclusion: The present study has confirmed similar findings from other different countries that declining sperm counts in humans is not a global phenomenon.

1 Introduction

In addition to the high population growth in many developing countries, the other fact that has come to light is that large cohorts of men in the reproductive age are in fact infertile. Although no conclusive epidemiological data on male infertility is available, it is a revelation that in approximately 30 % of the subjects attending a fertility clinic, the pathology lies with the man alone [1, 2]. In most cases, however, quality of the semen has been implicated as the cause. Controversy, thus, remains whether there is a decline in the semen quality over the years as first reported by Carlsen et al. [3]. The concerns were further supported by the fact that many environmental pollutants have been recognized as factors affecting fertility since they possess estrogen like effects [4].

Evidence of deteriorating semen quality was indicated in papers from many countries [5, 6]. In contradiction, a recent study [7] in the United States reported no decline in sperm density in men presenting for an initial screening of semen analysis. To the best of our knowledge, no specific study in this regard was ever reported from India till date, which houses one sixth of the world's growing population. In the absence of any fertility based epidemiological data bank in India, the present study was, thus, designed for the following objectives: (1) whether quality of semen, specifically, sperm count and motility are declining in India and (2) whether any relationship exists between sperm count and other variables such as income, occupation and age of subjects as included in the study records for the last 11 years (1990~2000).

2 Materials and methods

The outdoor clinic at National Institute of Health and Family Welfare (NIHFW), New Delhi (India), has been providing the infertility related services for more than 20 years and caters to people from different strata of the society from all over the country. As indicated, the data for the present study were taken from the records of subjects attending NIHFW's Infertility Clinic for the years starting from 1990 till 2000. Approximately 10 % of the records (n=1176) were randomly selected for analysis. In order to eliminate any selection bias, the subject data were randomly picked up for inclusion by auxiliary paramedical staff not connected with the study. The men in the study group had not receive any medical advice or intervention from any source. The semen analysis at the time of first screening was included for analysis. Data on subjects with azoospermia or severe oligozoospermia (<1010⁶/mL) were excluded. Analysis of data was carried out using software Statistical Package for Social Sciences (SPSS).

3 Results

The mean values on some of the important variables were shown in Figure 1. The average age of men who registered in the Infertility Clinic during the last 11 years was 31.2 years. The average semen volume and sperm counts were 2.6 mL0.1 mL and (60.60.9) 10⁶/mL, respectively. Only 1.8 % of the subjects in the study group showed counts less than 2010⁶/mL. No perceptible decline in the sperm counts was observed in the last eleven years (Figure 2). The average sperm motility pooled together in all the three categories of rapid linear progressive (RLP), sluggish linear progressive (SLP) and non-progressive (NP) was 67 %. Non-motile sperms in the semen, on an average, accounted a mere 33 %. However, the combined percentage (63 %) of non-progressive and non-motile sperm was considerably higher in these subjects (Figure 3).

Figure 1. MeanSEM of four variables as analyzed from the data sheets of the subjects.

Figure 2. Median sperm concentrations of subjects showing no significant decline over the last 11 years (1990 ~ 2000).

Figure 3. Percentage of semen quality in terms of motility. Total sperm motility is found to be 67 % (normal >50 %). RLP-Rapid linear progressive, SLP- Slow linear progressive, NP-Non-progressive, NM-Non-motile.

No significant correlation was found between age and occupation of subjects and the sperm counts. A significantly higher percentage of couples with income less than Rs. 25,000/year reported the center for infertility investigations as compared to other higher income groups. Higher income subjects showed a positive (P<0.05) correlation with an increased sperm count (Table 1). There was no specific correlation between subjects with low sperm count and their occupation. Similarly, sperm count and motility (percentage of RLP and SLP) revealed no significant correlation. A higher percentage of those in government service preferred to avail the services in the fertility centre as compared to people from other occupations (Table 2). A positive correlation was observed between age of individual subjects and percentage of non-motile sperm found in the ejaculate (coefficient r = 0.064, P<0.05). The average sperm count for non-motile sperm in the age group of 41 yrs and above was significantly (P<0.01) higher compared to those up to 25 yrs (Table 3). The rise in the average non-motility percentage in sperm was consistent with the increasing age of subjects. However, there was no significant increase in sperm non-motility when analyzed on a year-to-year basis (Table 3).

Table 1. Average sperm count (million/mL) versus income/Yr amongst subjects attending the Fertility Clinic for 11 years (1990~2000) at NIHFW, New Delhi, India.

Table 2. Average sperm count (million/mL) versus occupation among subjects attending the Fertility Clinic for 11 years (1990~2000) at NIHFW, New Delhi, India. n = 1174 (Information on occupation was not reported in two cases).

Table 3. Average non-motile sperm (%) in semen from subjects of different age groups attending the Fertility Clinic for 11 years (1990-2000) at NIHFW, New Delhi, India.

There is wide spread concern that environmental pollutants acting as xenoestrogens would affect human fertility adversely [8, 9]. Whether it had already made an impact on human fertility worldwide is debatable at the present stage. However, it is Carlsen's analysis [3] that sperm concentrations have decreased over the years in the last 50 years has triggered a renewed attention and curiosity amongst peer groups in different parts of the world. Though Carlsen's mode of data analysis was criticized in many fronts, many other similar studies that appeared subsequently [10, 11] contradicted each other. One sixth of the world's populations live in India. Besides the 14 subjects (from India) that were included in Carlsen's secondary analysis of world data, no other independent evaluations of semenology data from subjects, in similar lines, are available from the Indian subcontinent.

Poor semen quality is attributed as the major factor for decline in fertility rates in a developed country like Denmark [12] where more than 30 % of the 19-year-old men from the general population were shown to have sperm counts in the sub-fertile range. In our findings there was no significant decline in the sperm counts observed for the study period, which was in complete agreement with data recently published [7]. Though the over all average sperm motility was 67 % and non motility 33 %, the combination of poor and non-motile sperm represented a little over 60 % of the total motility. The non-motile percentage of the sperm is seen to have a significant relationship with age of the subjects indicating that the proportion of non-motile sperm might be increasing with advancing age. However, an anomaly in the trend was observed only for the year 1996 in which the age group of up to 25 yrs had higher percentage of non motile sperms compared to the group 41 yrs and above. Standard error of mean for sperm counts was also comparatively high for the same year (Figure 2). This may be attributed to errors while sampling. It has, however, not affected the overall sperm motility when analyzed on a yearly basis (Table 3). Reduction in sperm motility but not sperm function in the older people was also reported [13, 14]. Besides age, environment , sperm mitochondrial memberane and oxidative stress factors also play an important role in spermatogenic regulation and sperm are stated to be most susceptible to oxidative stress [15-17]. The increase in the percentage of sperm non-motility with age may be attributed to an enhanced sperm susceptibility to such stress factors. The study has revealed that more couples with lower income (<Rs. 25,000/year) seem to have attended the fertility clinic as compared to those with a higher income. No particular occupational factor could be implicated to infertility or lowered sperm counts in subjects attending the clinic (Table 2).

There is no denial to the fact that many of the subjects may not be normal in the true sense of the word as they are part of the group from the general population attending a fertility clinic. However, the counter argument in favor of the study comes from the fact that had there been a trend of declining in sperm counts in the general population, this would have been first noticed in subjects attending a fertility check-up. The random sampling of the data revealed that only a meager 1.8 % of the subjects showed counts less than 2010⁶/mL. This along with the fact that there is no other authenticated epidemiological data base in India for studies like this, the source of data from the fertility clinic at NIHFW, New Delhi was considered as the best recourse for such an analysis.

In conclusion, though parallel analysis of data from other parts/centers in India is necessary for further validation, the present findings indicate that the claim of declining sperm counts may not be global phenomenon.

References

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Correspondence to: Dr. M. M. Misro, Associate Professor, Department of Reproductive Biomedicine, National Institute of Health and Family Welfare, Munirka, New Delhi-110067, India.
E-mail: mm_misro@hotmail.com
Received 2003-04-09  Accepted 2003-07-18