Influence of climate on semen quality: A retrospective study

Abstract

Introduction:

World over studies are being done by different group of workers to understand the time of deliveries conducted. Surprisingly majority of deliveries were following a pattern, seasonally. Today in this busy world, couples choose comparatively a free time for delivery and preparation for conception is done accordingly. Apart from these, it is clearly shown majority of deliveries are conducted during a particular season. We hypothesised that the change in semen quality during different seasons is responsible for this phenomenon.

Materials and methods:

Present study conducted on semen quality included 12,408 semen samples collected from different laboratories of Bangalore city during 8 years (2000–2007) period of time and were analysed season wise.

Results:

Results showed sperm concentration was significantly lower in monsoon than in winter season. Humidity and pressure influenced sperm count. Forward moving sperms were influenced by temperature and pressure.

Summary:

The study concludes the change in birth rates seen during different season in a year is due to the quality of semen responsible for conception.

Keywords

Conception climate delivery semen quality sperm count sperm motility

Introduction

The topic ‘Human Fertility’ remains interesting for all. Researchers dig out new facts to make it further interesting. Some of them are concentrating on birth rate at different seasons. Another group of workers are measuring the depth of childlessness in society. Failure of fertility of male and female separately studied.

Male factor alone is responsible for 20% of infertility and is a contributory factor to infertility of 30%–40%.¹ It has been estimated that male factors, mainly poor semen quality, is responsible for 20%–70% of infertility cases.² Worldwide 30 million men are infertile.² Male infertility is increasing world over. Rate reported by authors from different parts of the world is shown in Table 1 which illustrates the seriousness.

Table 1.

Male infertility rate from different countries.

Country	Male infertility (%)
Sub Saharan Africa²	2.5–4.8
North America²	4.5–6
Europe²	7.5
Central/Eastern Europe²	8–12
Australia²	8
Oceania²	9
Northern Italy²	20
Singapore³	23
Pakistan⁴	26
Israel⁵	28
West Germany⁶	28
Bangladesh⁷	29
The United Kingdom⁸	30
France⁹	35
India–Bengaluru¹⁰	35
India–Kolar¹¹	42
India–Jamnagar¹²	45
India–Belagavi¹³	62
India–Ahmedabad¹⁴	64
India–Wardha¹⁵	65
India–Jamnagar¹¹	75
India–Ahmedabad¹⁶	76
India–Delhi¹⁷	84

Child is a product of efforts of husband and wife, a look at the deliveries conducted in a hospital in a year shall show which are not distributed equally. Reasons for this is explained as planned pregnancy and calculated for convenience of delivery at free time of parents.¹⁸ Bobak and Gjonca¹⁹ observed a strong association between maternal socio demographic characteristics and birth of time. If not planned by couples as reports suggest the seasonal deliveries depend on fertility potentiality of partners of couple at that particular time. Pal and Gandotra¹⁸ from India reported in the month of April in 2012, 2015 and 2016 delivery rate was lowest and highest delivery rate was in the month of August in 2012, 2014 and 2016.

We initiated this study to understand the seasonal role of male partners in fertility. The study was conducted by analysing the semen records collected from the city of Bangalore for a period of 7 years (2000–2007).

Materials and methods

Bangalore city is situated on southern part of our country, India. Presently city has a population of 13,193,000 (www.macrotrends.net. Bangalore, India Metro Area Population 1950–2022). The city experiences distinguished climates as shown below.

Seasons	Period
Winter	December–February
Summer	March–May
Monsoon	June–September
Post monsoon	October–November

In this retrospective study we analysed semen quality seasonwise from available reports. We analysed 8 years (2000–2007) of semen reports collected from following 12 clinical laboratories situated in Bangalore city.

Bangalore Medical College

Kempegowda Medical College

St. John’s Medical College

Ramaiah Medical College

Bangalore Hospital

Command Hospital

Rajeev Diagnositics

Mallya Hospital

Gunasheela Maternity Hospital

Manipal North Side Hospital

Kanya Diagnostic Services Pvt Ltd

Bowring and Lady Curson Hospital

Date wise reports of semen evaluation were provided by above pathology laboratories. We studied and analysed these reports which helped to find out the fertility status of men in each season.

We collected metrological data of each day of the study period and incorporated.

We were unable to get consent from patients as this is a retrospective study. Usually laboratories advice patients to collect semen without missing any drop²⁰ for examination after maintaining an abstinence of 2–5 days.^21,22
–24 Semen parameters are influenced by external temperature and daylight duration.²⁵ Due to these reasons each sample is studied immediately after liquefaction. Regularly laboratories maintain steady temperature and light during semen examination. Experimental studies proved light influences sperm motility.²⁶ Fertility parameters followed in this study are total volume (in ml), viscosity, total sperm count (million/ml), percentage of sperm motility, actively forward moving sperm and sperm morphology.

Methods of statistical analysis

For studying the correlation of Fertility Parameters with Season we used the statistical techniques, mean and standard deviation of the Weather Parameter according to Season, correlation coefficient of Fertility Parameters among Weather Parameter and each parameter among season, Chi-square test used for testing the association between parameters according to season and Analysis of Variance for comparing mean difference of Fertility Parameters. All the analysis were done in the statistical software SPSS (Statistical Package for Social Sciences) 20.00 version.

The study was initiated after getting approval of the same from Research committee and Ethical committee of the institution.

Results

Distribution of total semen reports (12,408) collected from 12 clinical laboratories during 8 years is shown in month and year wise (Table 2).

Table 2.

Distribution of subjects according to month and year.

	Month	Year								Total
	Month	2000	2001	2002	2003	2004	2005	2006	2007	Total
Winter	December	114	101	100	139	200	145	165	97	1061
	January	92	100	105	147	179	152	156	108	1039
	February	220	111	158	154	155	41	141	111	1091
Summer	March	138	117	132	119	194	41	148	106	995
	April	116	131	148	140	200	121	175	102	1133
	May	96	127	153	173	163	177	143	0	1032
Monsoon	June	107	121	136	174	148	124	160	0	970
	July	89	118	191	168	154	143	127	0	990
	August	122	120	181	140	128	153	169	0	1013
	September	109	122	153	162	142	133	120	0	941
Post monsoon	October	102	118	142	147	181	153	141	100	1084
Post monsoon	November	126	108	99	158	191	148	143	86	1059
	Total	1431	1394	1698	1821	2035	1531	1788	710	12,408
	Percentage	11.5	11.2	13.7	14.7	16.4	12.3	14.4	5.7	100

Reports during four seasons are tabulated and presented in Table 3.

Table 3.

Shows the distribution of subjects according to seasons (winter, summer, monsoon and post monsoon) and year.

Seasons	Year								Total
Seasons	2000	2001	2002	2003	2004	2005	2006	2007	Total
Winter	426	312	365	440	534	338	462	316	3191 (25.7)
Summer	350	375	433	432	557	339	466	208	3160 (25.4)
Monsoon	427	481	661	644	572	553	576	0	3914 (31.5)
Post monsoon	228	226	241	305	372	301	284	186	2143 (17.2)
Total	1431 (11.5)	1394 (11.2)	1698 (13.7)	1821 (14.7)	2035 (16.4)	1531 (12.3)	1788 (14.4)	710 (5.7)	12,408 (100)

Table 4 shows the association of subjects according to sperm count (million/ml) and season.

Table 4.

Association of subjects according to sperm count (million/ml) and season.

Season	Sperm count			Total number of samples studied	p-Value
Season	Normozoospermia: >40 million/ml	Oligozoospermia Oligoasthenozoospermia: ⩽40 million/ml	Azoospermia: Nil	Total number of samples studied	p-Value
Winter	1176 (54.9)	769 (35.9)	198 (9.2)	2143 (17.3)	>0.010
Summer	1717 (53.8)	1152 (36.1)	321 (10.1)	3190 (25.7)
Monsoon	2112 (51.0)	1540 (37.2)	483 (11.7)	4135 (33.3)
Post monsoon	1556 (52.9)	1055 (35.9)	329 (11.2)	2940 (23.7)
Total	6561 (52.8)	4516 (36.4)	1331 (10.7)	12,408

Sperm count is categorised as: Normoozospermia (>40); Oligozoospermia, Oligoasthenozoosperma (⩽40) and Azoospermia (00) (Table 4).

Table 5 shows sperm count and motility (%) among seasons.

Table 5.

Association of subjects according to sperm motility and season.

Season	Sperm motility (%)			Total	p-Value
Season	Normozoospermia >60 %	Subnormal <60%	Azoospermia	Total	p-Value
Winter	1511 (92.2)	127 (7.8)	872	1638 (18.4)	0.571
Summer	2179 (91.5)	202 (8.5)	872	2381 (26.7)
Monsoon	2574 (91.7)	233 (8.3)	872	2807 (31.5)
Post monsoon	1905 (91.0)	189 (9.0)	872	2094 (23.5)
Total	8169 (91.6)	751 (8.4)		8920*

There was not much difference in sperm motility during different seasons.

Seasonal variation in fertility parameters are considered according to season (Table 6).

Table 6.

Fertility parameters (Mean ± SD) according to season.

Fertility parameters		Winter (Dec–Feb)	Summer (Mar–May)	Monsoon (June–Sept)	Post monsoon (Oct–Nov)
Volume	n	1624	2313	2771	2019
	Mean	2.618	2.55	2.59	2.56
	SD	1.423	1.319	1.545	1.34
Viscosity	n	1599	2272	2631	1959
	Mean	1.36	1.33	1.33	1.34
	SD	0.680	0.641	0.650	0.660
Sperm count	n	2143	3190	4122	2940
	Mean	62.032	60.51	53.69	58.16
	SD	61.041	62.99	54.18	60.28
Motility	n	1638	2381	2807	2094
	Mean	92.24	91.59	91.81	90.995
	SD	26.78	27.66	27.39	28.669
g1 (Actively forward moving Sperm)	n	2111	3188	4075	2941
	Mean	39.66	34.67	34.29	38.37
	SD	30.61	29.45	29.65	29.64
g2 (Medium)	n	2110	3189	4075	2941
	Mean	16.18	17.72	18.66	14.94
	SD	26.06	26.43	26.96	23.96
g3 (Sluggish)	n	1640	2384	2853	2096
	Mean	37.59	41.33	41.04	38.89
	SD	27.08	28.41	28.83	27.89
Morphology	n	997	1392	1680	1281
	Mean	21.43	21.51	19.80	20.269
	SD	22.65	24.51	22.57	22.892

n = number of samples.

We have studied weather parameters according to seasonal variation with maximum temperature, rainfall, humidity 1, humidity 2, Pressure 1, Pressure 2 and total sunshine and are shown in Table 7.

Table 7.

Weather parameters (Mean ± SD) according to season.

Weather parameters		Winter (Dec–Feb)	Summer (Mar–May)	Monsoon (June–Sept)	Post monsoon (Oct–Nov)
Max temp	n	1673	2413	2874	2099
	Mean	29.93	33.38	28.91	27.871
	SD	1.401	1.183	0.886	0.684
Min temp	n	1673	2413	2874	2099
	Mean	17.18	21.35	20.10	17.778
	SD	1.001	0.942	0.382	1.781
Rainfall	n	1673	2413	2874	2099
	Mean	6.059	67.68	129.15	76.601
	SD	14.93	82.79	81.00	88.399
Humidity 1	n	1673	2413	2874	2099
	Mean	75.77	72.16	86.30	80.097
	SD	6.559	6.664	2.24	4.339
Humidity 2	n	1673	2413	2874	2099
	Mean	39.46	41.36	66.45	60.191
	SD	6.565	12.31	4.478	8.718
Pressure 1	n	1673	2413	2874	2099
	Mean	912.29	909.79	907.89	911.65
	SD	0.913	1.313	1.0198	1.39
Pressure 2	n	1673	2413	2874	2099
	Mean	908.87	906.053	905.21	908.63
	SD	0.906	1.065	0.742	1.37
Total sunshine	n	1673	2413	2874	2099
	Mean	220.44	222.674	116.81	174.79
	SD	22.39	32.274	22.925	35.09

n = number of samples.

Seasonal variation in semen quality was studied and shown in Table 8. Total study showed sperm concentration in monsoon (53.69 million/ml) was significantly (p < 0.001) lower than that in winter (62.03 million/ml). We identified the seasonal variation in actively forward moving sperms (g1), medium (g2) and sluggish (g3) which are highly significant (Table 8). Statistically highly significant values were present in sperm count, actively forward moving sperm, medium moving sperm and sluggish moving sperm.

Table 8.

Comparison of means between fertility parameters and seasons.

Factors		Mean	SD	p-Value
Volume	Winter (1624)	2.62	1.423	0.530
	Summer (2313)	2.55	1.319
	Monsoon (2771)	2.59	1.545
	Post monsoon (2019)	2.58	1.343
pH	Winter (2143)	1.00	0.061	0.495
	Summer (3191)	1.00	0.064
	Monsoon (4130)	1.00	0.049
	Post monsoon (2944)	1.00	0.049
Viscosity	Winter (1599)	1.36	0.680	0.360
	Summer (2272)	1.33	0.641
	Monsoon (2631)	1.33	0.650
	Post monsoon (1959)	1.34	0.660
Sperm count	Winter (2143)	62.031	61.041	<0.001
	Summer (3190)	60.505	62.994
	Monsoon (4122)	53.691	54.179
	Post monsoon (2940)	58.155	60.276
(g1) Actively forward moving Sperm	Winter (2111)	39.659	30.605	<0.001
	Summer (3188)	34.665	29.446
	Monsoon (4075)	34.296	29.651
	Post monsoon (2941)	38.370	29.636
(g2) Medium	Winter (2110)	16.175	26.056	<0.001
	Summer (3189)	17.717	26.426
	Monsoon (4075)	18.656	26.963
	Post monsoon (2941)	14.939	23.956
(g3) Sluggish	Winter (1640)	37.586	27.084	<0.001
	Summer (2384)	41.328	28.408
	Monsoon (2853)	41.045	28.829
	Post monsoon (2096)	38.887	27.895
Morphology	Winter (997)	21.427	22.654	0.132
	Summer (1392)	21.509	24.512
	Monsoon (1680)	19.803	22.571
	Post monsoon (1281)	20.269	22.892
Motility	Winter (1638)	92.243	26.784	0.564
	Summer (2381)	91.593	27.656
	Monsoon (2807)	91.816	27.390
	Post monsoon (2094)	90.995	28.669

Table 9 shows comparison of mean of sperm count between seasons. At two levels, between (a) winter and monsoon and (b) summer and monsoon, the values were statistically highly significant.

Table 9.

Comparison of mean of sperm count within seasons.

Season		Mean difference	SE	p-Value	95% confidence interval
Season		Mean difference	SE	p-Value	Lower bound	Upper bound
Winter	Summer	1.526	1.653	1.000	−2.835	5.888
	Monsoon	8.340	1.576	<0.001	4.181	12.499
	Post monsoon	3.876	1.681	0.127	−0.559	8.312
Summer	Monsoon	6.813	1.396	<0.001	3.1309	10.496
Summer	Post monsoon	2.350	1.513	0.723	−1.642	6.343
Post monsoon	Monsoon	4.464	1.428	<0.011	0.693	8.234

Correlation of fertility parameters among weather parameters is shown in Table 10. Low degree of correlation was seen.

Table 10.

Correlation of fertility parameters among weather parameters.

Parameters		Max temp	Min temp	Rainfall	Humidity 1	Humidity 2	Pressure 1	Pressure 2	Total sunshine
Volume (8713)	R	−0.013	−0.014	−0.018	0.011	0.003	−0.004	0.001	−0.002
Volume (8713)	p-Value	0.238	0.188	0.096	0.284	0.764	0.703	0.959	0.850
pH (9059)	R	0.006	0.006	0.018	0.003	0.002	−0.010	−0.012	0.009
pH (9059)	p-Value	0.539	0.573	0.094	0.793	0.827	0.364	0.261	0.396
Viscosity (8447)	R	0.010	−0.010	−0.016	−0.025	−0.025	0.055	0.048	0.026
Viscosity (8447)	p-Value	0.339	0.353	0.154	0.020	0.023	<0.001	<0.001	0.015
Sperm count (9046)	R	0.036	0.000	−0.027	−0.063	−0.057	0.047	0.037	0.035
Sperm count (9046)	p-Value	0.001	0.968	0.009	<0.001	<0.001	<0.001	<0.001	0.001
g1) Actively forward moving Sperm (8969)	R	−0.047	−0.082	−0.025	−0.031	−0.011	0.064	0.068	0.020
g1) Actively forward moving Sperm (8969)	p-Value	<0.001	<0.001	0.016	0.004	0.290	<0.001	<0.001	0.058
(g2) Medium (8970)	R	0.059	0.070	−0.040	0.011	−0.032	−0.016	−0.022	0.001
(g2) Medium (8970)	p-Value	<0.001	<0.001	<0.001	0.315	0.002	0.120	0.039	0.902
g3) Sluggish (8959)	R	0.006	0.044	0.056	0.031	0.034	−0.059	−0.058	−0.027
g3) Sluggish (8959)	p-Value	0.598	<0.001	<0.001	0.003	0.001	<0.001	<0.001	0.010
Morphology (5336)	R	0.030	−0.003	−0.025	−0.026	−0.033	0.018	0.012	0.041
Morphology (5336)	p-Value	0.026	0.819	0.067	0.060	0.015	0.192	0.391	0.003
Motility (8906)	R	−0.002	0.001	−0.002	0.001	−0.003	0.003	0.003	−0.002
	p-Value	0.821	0.935	0.854	0.931	0.796	0.793	0.765	0.869

n = number of samples in brackets.

Correlation of fertility parameters were compared with weather parameters as shown in Table 10. It was observed no much influence of different weather parameters. Humidity and pressure influenced sperm count; maximum temperature, minimum temperature, pressure 1 and pressure 2 influenced actively forward moving sperms; maximum temperature, minimum temperature and rainfall influenced medium moving sperms and minimum temperature, rainfall; pressure 1 and pressure 2 influenced sluggish motile sperms.

Table 11 shows the association of combinations of fertility parameters and seasons.

Table 11.

Association of combination of fertility parameters and seasons.

Season	Combination		Total	p-Value
Season	Normal (Normzoospermia)	Subnormal (Oligozoospermia + Asthenozoospermia + Oligoasthenospermia + Azoospermia)	Total	p-Value
Winter	617 (61.6)	384 (38.4)	1001 (17.9)	0.124
Summer	927 (61.9)	570 (38.1)	1497 (26.8)
Monsoon	1058 (59.4)	724 (40.6)	1782 (31.9)
Post monsoon	800 (61.3)	505 (38.7)	1305 (23.4)
Total	3402 (60.9)	2183 (39.1)	5585

Out of total semen examined, 60.9% were normal. It was observed maximum number of normal semen samples were submitted in monsoon season (59.4%).

Discussion

Many reports are available showing difference in deliveries during different months or seasons.¹⁸ Becker,²⁷ Mascarenhas et al.²⁸ and Roenneberg and Aschoff²⁹ reported significant seasonal variation in the birth rate. In United States maximum deliveries were conducted during summer (in the month of August). During winter, according to demographic reports, couples spend more time indoors and in summer babies are born³⁰ and a trough during April–May.^31,32 In Japan in a year birth rates are seen in two peaks from December to February and from August to September.³⁰ Seasonal variation in human birth rate is a global phenomenon.^33,34 Many reasons are proposed or postulated.^35
–39 Some believed this may be due to increased conception rate in summer. Possibly changes in hormone levels in both partners affect conception. Cowgill^40
–42 believed seasonality of births may be due to two factors: (1) geographical or climatic factors such as temperature, rainfall, relative humidity, wind velocity, duration of sunshine, lunar phases and (2) cultural and economic factors. In modern times, couples pre plan delivery time to suit their busy day to day life. Convenience of vacation period is the choice among several couples. Many hypotheses have been postulated on the seasonality of birth rates like seasonality of marriages, changes in frequency of sexual intercourse due to differences in availability of leisure time, changes in weather conditions and seasonality of biological chances of conception. In modern societies, however, it is likely that the probability of conception depends more on the choice of the time of pregnancy than on climate or duration of marriage.^{18,35,39,43,44} Prasad et al.⁴⁵ opined while considering on seasonality of births sociocultural factors should be considered.

Talwar et al.⁴⁶ have chosen a small area in Union Territory of Chandigrah (India) where the population experiences same climate. They reported maximum number of births take place during September and October months and the minimum in April. Large number of conception are taken place in lower temperature of season (December, January, February). During summer and rainy seasons conception rate is low. Their study concluded that below 25°C atmosphere conception rate is high. Thus atmosphere temperature influences reproduction in man. Another report from India shows maximum deliveries are conducted in the months of August to October and lowest from April to June.⁴⁷ Supporting above study maximum conception rates are in winter season and minimum conception is in summer season. These findings will prove valuable in health system planning and in the interpretation of seasonal variations in other reproductive parameters.²⁸ Authors reported during warmer seasons spouses sleep separately probably a cause for less conceptions and in colder seasons spouses more commonly sleep together leading to increase in conception rate. Same was reported by Paul Sutton from USA.³⁰

Another opinion on the seasonal variation seen in deliveries is explained as due to seasonal changes in semen quality.²⁵ Semen examination is carried out when fertility potentiality of a person is in question.² Infertility affects world over an estimated 48.5 million couples. Deterioration of semen quality is the main cause of male infertility. Semen examination is routinely done after liquefaction of sample is over. Reports show quality of semen is continuously declining globally.^48,49 Several workers are in search of causes. Geographical differences in semen quality was reported by Alvin Paulsen et al.⁵⁰ Contradictively, Gyllenorg et al.⁵¹ reported from their retrospective study from 1997 to 1995 a significant increase in sperm concentration and total sperm count. They observed from 1927 semen donors seasonal variation in sperm concentration and total sperm count. This is strongly indicating seasons influence testicular function. A limited number of epidemiological studies were done to observe the seasonal fluctuation of semen quality.^25,52 Santi et al.²⁵ opined semen parameters show a seasonal change, with a fluctuation during the year related to temperature and daylight duration. Ombelet et al.⁵³ failed to find out any significant difference in semen parameters during the whole year. However, the details of semen quality during different seasons are scanty.

We were interested to identify changes in quality of semen during different seasons. We have collected data of 12,408 of semen samples of 8 years period of time and their distribution, month and year wise is shown in Table 2. This included in all four seasons present in this area (Table 3 and Figure 1).

Figure 1.

Shows average total sperm count (million/ml) and sperm motility (%) during different seasons.

Smoking may alter semen parameters.⁵⁴ We have not included the history of smoking habit of semen suppliers as ours is a retrospective study. Age of semen suppliers is important. In our present study the age of theirs varied from 20 to 33 years. As the age increases semen parameters like volume, sperm concentration and total sperm motility deteriorate.^54
–56 There was a significant decrease in daily sperm production and decrease in motility and morphology in elderly men.^56
–58 A weak positive correlation between percent tail defects and age was reported which increases as age advances. Zhou et al.⁵⁹ reported decreased sperm motility in the older group.

According to the nomenclature semen reports of all four seasons were divided into normal and pathological as shown in Table 4.

Semen quality differed geographically.^50,60 In fact, substantial geographical variation in sperm concentrations is possible.⁵²

Studies were done to know the effect of environment on semen quality.^61,62

Reports differed about total semen volume. We did not find any significant change in volume during different seasons (Table 6). Others^63
–65 supported the same. Centola and Eberly⁵⁵ observed volume was highest during spring time, April–May.⁶⁶

Environmental temperature influences on semen quantity and quality.⁵² Seasons (change in temperature) may be influencing semen production and sperm functioning and this is a possible reason for difference in birth rate during different timings of a year. We reported no significant changes in semen picture when normal subjects who supplied samples three times in 1 month period after maintaining an abstinence of 5 days. This study excluded influence of season on semen, but showed no within subject variation.⁶⁷ Alvarez et al.⁶⁸ reported similarly.

Andolz et al.⁶⁵ observed variations in total sperm count and motility during different seasons. Levine et al.⁶³ showed the importance of environmental temperature on human reproductive function.

In the present study Seasonal variations in fertility parameters are studied. Sperm Count, g1 (Actively forward moving Sperm), g2 (Medium), g3 (Sluggish) and Morphology are shown changes among seasons (Table 6).

Samples with normal count was observed maximum (54.9%) during winter and minimum (51%) during monsoon which was statistically significant (Table 4 and Figure 1). The mean sperm concentration in monsoon (53.69 million/ml) was significantly lower than in winter (62.03 million/ml; p < 0.001) (Table 8). In comparison between means of sperm count according to season, there were significant differences between means among winter, summer and post monsoon with respect to monsoon (Table 9). Saint Pol et al.⁶⁴ and Levine et al.⁶³ reported a significant seasonal variation in sperm count, with the highest sperm counts observed in late winter and early spring and the lowest in late summer. Henkel et al.⁶⁹ in their study demonstrated seasonal changes in Neutral Alpha Glucosidase which is correlated with sperm concentration. Carlsen et al.⁷⁰ did not observe any significant seasonal variations in sperm concentration, motility or morphology.

Data collected from different sources are calculated and presented in Table 12.

Table 12.

Normal values of semen parameters during different seasons.

Season	Volume (2–6 ml) (%)	Viscosity (fluid) (%)	pH (%)	Sperm Count (million/ml) (%)	Sperm motility (%)
Winter	67.3	75.3	99.6	54.9	92.2
Summer	69.4	75.9	99.6	53.8	91.5
Monsoon	69.9	77.5	99.8	50.9	91.7
Post monsoon	69.2	76.3	99.8	52.9	91.0
Total		76.4	99.7		91.6

From available data the association of subjects according to sperm motility (Normal (>60) and Subnormal (⩽60)) and season is shown in Table 5. Statistically it was not significant. There were also seasonal variations in (g1) actively forward moving Sperm, (g2) Medium and (g3) Sluggish are highly significant (Table 8). De Giorgi et al.⁷¹ observed higher sperm motility in summer when compared to other seasons whereas Levine et al.⁷² observed deterioration of semen quality in summer season.

Sperm concentration and percentage of sperm morphology was higher in winter than in other seasons.^54,64 Correlation of subjects among fertility parameters according to Weather Parameters shows low degree of correlation (Table 10). Seasonal variation in semen quality was reported by few groups of workers.^25,52 Santi et al.²⁵ observed seasonal change in semen parameters exclusively related to temperature and daylight duration. They advised seasonal and environmental factors should be considered while assessing semen for finding causes of male infertility.

Levine⁷³ opined that high temperatures interfere with spermatogenesis and lower sperm quality which may be the reason for lower conceptions in summer.

Seasonal variations in semen parameters have been reported in both fertile and infertile men in our study and supported by other studies.^55,63,64 Levine et al.⁶³ observed deterioration in semen quality occurs in hot climate in men with little or no access to air conditioning to moderate the hot temperatures, confirming the importance of environmental temperatures on human reproductive function. That high ambient temperature as well as low temperature exposure was significantly associated with decreased semen quality. Importance of ambient temperature for optimal semen quality for men is now known.

The process of spermatogenesis is very sensitive to temperature. An optimal temperature in scrotum for normal spermatogenesis is 2°C–4°C below the core body temperature.^59,74 Function of scrotal sac is to maintain suitable temperature for the testes.

A cause for increased infertility is high scrotal temperature which changes seminal parameters. This was observed in both human and animal models.⁷⁵ Thonneau et al.⁷⁶ introduced heat exposure as a risk factor in man’s fertility. With respect to the absolute temperature, men with a scrotal skin temperature above 35°C for more than half of the daytime may be at risk as far as spermatogenesis is concerned.⁷⁷ The sedentary position of a man due to occupation or otherwise is likely to increase scrotal temperature and is a probable reason for infertility.⁷⁸

Semen parameters in workers exposed to heat were significantly lower than controls.^79
–82 It is now established that high environmental temperature cause decrease in semen quality.^25,52 During summer months greater numbers of sperms were seen with bend tail mid pieces.^55,63 However Mortimer et al.⁸³ found no seasonal variation in motility.

Concomitantly, the incidence of male infertility has been increasing in industrial countries year after year, now affecting 25% of young men. We reported male infertility rate as much higher in industrial cities like Ahmedabad and Surat (Table 1). It is known that Air pollution has a negative effect on semen quality. Chronic exposure to ambient pollutants at high level may alter men sperm quality.⁸⁴ Air pollution may be a responsible factor for reported increase in male infertility.^14,16,85

In a four hourly ejaculate study it was reported a decrease in total sperm count and increase in percentage of motility from first to fifth sample.²¹

Footnotes

Author contributions

Skandhan and Avni KP Skandhan collected the data from different laboratories and arranged season wise. KR Sundaram and Greeshma bio statistically analysed the data and the shape of this manuscript is made by KP Skandhan, Avni KP Skandhan and BS Prasad.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Expenses towards collection of semen data and meteorological data was done from Sri Devraj Urs Medical College.

ORCID iD

Skandhan Padmanabhan

References

Thonneau

Marchand

Tallec

, et al. Incidence and main causes of infertility in a resident population (1 850 000) of three French regions (1988–1989)*. Hum Reprod 1991; 6: 811–816.

Agarwal

Mulgund

Hamada

, et al. A unique view on male infertility around the globe. Reprod Biol Endocrinol 2015; 13: 37–40.

Ratnan

Chew

PCT

Tsakok

Experience of a comprehensive infertility clinic in the Department of Obstetrics and Gynecology, University of Singapore. Singap Med J 1976; 17(3): 157–159.

Butt

Akram

Semen analysis parameters: experiences and insight into male infertility at a tertiary care hospital in Punjab. J Pak Med Assoc 2013; 63(5): 558–562.

Dor

Homburg

Rabau

An evaluation of etiologic factors and therapy in 665 infertile couples. Fertil Steril 1977; 28(7): 718–722.

Semm

Brandl

Mettler

Vacuum insemination cap. In: Hafez

ESE

(ed.) Human semen and fertility regulation in men. St. Louis, MO: The CV Mosby Company, 1976, pp.439–441.

Chowdhury

Khanam

Akhter

, et al. Profile of 350 couples attending the infertility clinic at P.G. hospital. In: Fifth contributors conference, Dacca, Bangladesh, 1981, p.85. Dacca: Bangladesh Fertility Research Programme.

Chandley

. Cytogenetics of infertile men. In: ESE

Hafez

(ed.) Human semen and fertility regulation in men. St. Louis, MO: The CV Mosby Company, 1976, pp.419–428.

Soutoul

Berger

Homasson

, et al. Marital sterility and etiological study and therapeutic results. Rev Fr Gynecol Obstet 1976; 71: 79–89.

10.

Biradar

Male factor in infertility: study from a tertiary care hospital. Int J Reprod Contracept Obstet Gynecol 2016; 5(6): 2022–2025.

11.

Prasad

Skandhan

Singh

Human semen study around and away from gold mine area. Urologia 2011; 78: 293–296.

12.

Mehra

Skandhan

Prasad

, et al. Male infertility rate: a retrospective study. Urologia 2018; 85: 22–24.

13.

Chaitrali

Santrupti

Niranjan

Skandhan

Sukumar

Prasad

. Male infertility rate in Belagavi, Karnataka, India. Int J Infertil Fetal Med 2019; 10: 1–3.

14.

Skandhan

Vadodaria

Langalia

, et al. Incidence of male factor in involuntary infertility. Andrologia 1982; 14: 328–330.

15.

Kumar

Choudhari

Singh

AK.

Prevalence of male factor infertility in last ten years at a rural tertiary care centre of central India: a retrospective analysis. Ind J Obstet Gynaecol Res 2015; 2: 132–136.

16.

Skandhan

Patel

Mehta

YB.

Rate of involuntary infertility among male partners. Ital J Med 1986; 2: 71–72.

17.

Jairajpuri

Rana

Ali

, et al. Patterns of semen analysis: Experiences of a laboratory catering to semi urban population of Delhi. Banglad J Med Sci 2017; 16(2): 314–319.

18.

Pal

Gandotra

The effect of seasonal variation on the delivery rate: a retrospective study. Int J Reprod Contracept Obstet Gynecol 2018; 7: 1101–1103.

19.

Bobak

Gjonca

The seasonality of live birth is strongly influenced by socio-demographic factors. Hum Reprod 2001; 16: 1512–1517.

20.

Skandhan

Valsa

Sumangala

, et al. Level of copper in human split ejaculate. Urologia 2017; 84: 51–54.

21.

Valsa

Skandhan

Gusani

, et al. Effect of daily ejaculation on semen quality and calcium and magnesium in semen. Andrologia 2013; 11: 94–99.

22.

Skandhan

Pandya

, et al. Daily ejaculates: level of zinc and copper in seminal plasma. Necessity for abstinence prior to semen collection. Infertility 1985; 8: 279–291.

23.

Valsa

Skandhan

Gusani

, et al. Quality of 4-hourly ejaculates–levels of calcium and magnesium. Andrologia 2013; 45: 10–17.

24.

Valsa

Skandhan

Sumangala

, et al. Time bound changes (in 24 h) in human sperm motility and level of calcium and magnesium in seminal plasma. Alex J Med 2016; 52: 235–241.

25.

Santi

Magnani

Michelangeli

, et al. Seasonal variation of semen parameters correlates with environmental temperature and air pollution: a big data analysis over 6 years. Environ Pollut 2018; 235: 806–813.

26.

Veena

Skandhan

Siraj

MVP

, et al. Effect of visible light on human sperm motility. Urologia 2012; 79: 266–270.

27.

Becker

Seasonal patterns of births and conception throughout the world. Adv Exp Med Biol 1991; 286: 59–72.

28.

Mascarenhas

Flaxman

Boerma

, et al. National, regional, and global trends in infertility prevalence since 1990: a systematic analysis of 277 health surveys. PLoS Med 2012; 9: e1001356.

29.

Roenneberg

Aschoff

. Annual rhythm of human reproduction: I. Biology, sociology, or both? J Biol Rhythms 1990; 5: 195–216.

30.

Charles

. In Which Month Are the Most Babies Born? Live Sci, August 19, 2022.

31.

Lam

Miron

JA.

Global patterns of seasonal variation in human fertility. Ann N Y Acad Sci 1994; 709: 9–28.

32.

Lam

Miron

JA.

The effects of temperature on human fertility. Demography 1996; 33: 291–305.

33.

Ellison

Valeggia

Sherry

DS.

Chapter 13. Human birth seasonality. In: DK

Brockman

(ed.) Seasonality on primates studies of living and extinct human and non-human primates. Cambridge: Cambridge University Press, 2005, pp. 379–399.

34.

Anand

Kumar

Kant

, et al. Seasonality of births and possible factors influencing it in a rural area of Haryana, India. Indian Pediatr 2000; 37: 306–312.

35.

Ayeni

Seasonal variation of births in rural southwestern Nigeria. Int J Epidemiol 1986; 15: 91–94.

36.

Matsuda

Kahyo

Geographical differences and time trends in the seasonality of birth in Japan. Int J Epidemiol 1994; 23: 107–118.

37.

Bernard

Bhatt

Potts

, et al. Seasonality of birth in India. J Biosoc Sci 1978; 10: 409–421.

38.

Stoeckel

Choudhury

AKMA

. Seasonal variation in births in rural East Pakistan. J Biosoc Sci 1972; 4: 107–116.

39.

Mathers

Harris

RS.

Seasonal distribution of births in Australia. Int J Epidemiol 1983; 12: 326–331.

40.

Cowgill

UM.

The season of birth in man. Man 1966; 1: 232–240.

41.

Cowgill

UM.

Season of birth in man: contemporary situation with special reference to Europe and the Southern Hemisphere. Ecology 1966; 47: 614–623.

42.

Cowgill

UM.

The season of birth in man: the Northern New World. Kroeber Anthropology Society Papers No. 35. California: Berkeley, 1966.

43.

Halli

SS.

The seasonality of births in Canada. J Biosoc Sci 1989; 21: 321–327.

44.

Erhardt

Nelson

Pakter

Seasonal patterns of conception in New York City. Am J Public Health 1971; 61: 2246–2258.

45.

Prasad

Srivastava

Bhushan

, et al. A study of seasonal variation of births at maternity hospitals of some medical colleges in India. Ind J Med Res 1969; 57: 718–729.

46.

Talwar

Upadhyay

Sharma

The seasonality of births in Chandigarh with special reference to climatic and cultural factors. Indian Anthropol 1986; 16: 23–32.

47.

Yadava

Dube

Marwah

SM.

A study of seasonal trends in delivery and medical termination of pregnancy. J Obstet Gynaecol India 1979; 29: 256–257.

48.

Carlsen

Giwercman

Keiding

, et al. Evidence for decreasing quality of semen during past 50 years. BMJ 1992; 305: 609–613.

49.

Swan

Elkin

Fenster

The question of declining sperm density revisited: an analysis of 101 studies published 1934-1996. Environ Health Perspect 2000; 108: 961–966.

50.

Alvin Paulsen

Berman

Wang

. Data from men in greater Seattle area reveals no downward trend in semen quality: further evidence that deterioration of semen quality is not geographically uniform. Fertil Steril 1996; 65: 1015–1020.

51.

Gyllenorg

Skakkeebaek

Nielsen

, et al. Secular and seasonal changes in semen quality among young Danish men: a statistical analysis of semen samples from 1927 donor candidates during 1977-1995. Int J Androl 1999; 22: 28–36.

52.

Santi

Vezzani

Granata

, et al. Sperm quality and environment: a retrospective, cohort study in a Northern Province of Italy. Environ Res 2016; 150: 144–153.

53.

Ombelet

Maes

Vandeput

, et al. Chronobiological fluctuations in semen parameters with a constant abstinence period. Arch Androl 1996; 37: 91–96.

54.

Chen

Toth

GodfreyBailey

, et al. Seasonal variation and age-related changes in human semen parameters. J Androl 2013; 24: 226–231.

55.

Centola

Eberly

Seasonal variations and age-related changes in human sperm count, motility, motion parameters, morphology, and white blood cell concentration. Fertil Steril 1999; 72: 803–808.

56.

Haidl

Jung

Schill

WB.

Ageing and sperm function. Hum Reprod 1996; 11: 558–560.

57.

Schwartz

Mayaux

M-J

Spira

, et al. Semen characteristics as a function of age in 833 fertile men. Fertil Steril 1983; 39: 530–535.

58.

Gallardo

Simón

Levy

, et al. Effect of age on sperm fertility potential: oocyte donation as a model. Fertil Steril 1996; 66: 260–264.

59.

Zhou

Meng

, et al. Association between ambient temperature and semen quality: a longitudinal study of 10 802 men in China. Environ Int 2020; 135: 105364.

60.

Suominen

Vierula

Semen quality of Finnish men. Br Med J 1993; 306: 1579.

61.

Auger

Kunstmann

Czyglik

, et al. Decline in semen quality among fertile men in Paris during the past 20 years. New Engl J Med 1995; 332: 281–285.

62.

Mendiola

Jørgensen

Andersson

, et al. Reproductive parameters in young men living in Rochester, New York. Fertil Steril 2014; 101: 1064–1071.

63.

Levine

Bordson

Mathew

, et al. Deterioration of semen quality during summer in New Orleans. Fertil Steril 1988; 49: 900–907.

64.

Saint Pol

Beuscart

Leroy-Martin

, et al. Circannual rhythms of sperm parameters of fertile men. Fertil Steril 1989; 51: 1030–1033.

65.

Andolz

Bielsa

Andolz

Circannual variation in human semen parameters. Int J Androl 2001; 24: 266–271.

66.

Reinberg

Smolensky

Hallek

, et al. Annual variation in semen characteristics and plasma hormone levels in men undergoing vasectomy. Fertil Steril 1988; 49: 309–315.

67.

Godatwar

Skandhan

Prasad

, et al. Within subject variation of seminal parameters after 5 days of abstinence. Int J Life Sci Pharma Res 2022; 12: 48–54.

68.

Alvarez

Castilla

Martínez

, et al. Biological variation of seminal parameters in healthy subjects. Hum Reprod 2003; 18: 2082–2088.

69.

Henkel

Maass

Schuppe

, et al. Seasonal changes of neutral alpha-glucosidase activity in human semen. J Androl 2006; 27: 34–39.

70.

Carlsen

Petersen

Andersson

, et al. Effects of ejaculatory frequency and season on variations in semen quality. Fertil Steril 2004; 82: 358–366.

71.

De Giorgi

Volpi

Tiseo

, et al. Seasonal variation of human semen parameters: a retrospective study in Italy. The journal of Bological and Medical Rhythm Research 2015; 32: 711–716.

72.

Levine

Mathew

Chenault

, et al. Differences in the quality of semen in outdoor workers during summer and winter. New Engl J Med 1990; 323: 12–16.

73.

Levine

RJ.

Seasonal variation of semen quality and fertility. Scand J Work Environ Health 1999; 25 Suppl 1: 34–37; discussion 76.

74.

Ivell

Lifestyle impact and the biology of the human scrotum. Reprod Biol Endocrinol 2007; 5: 15.

75.

Hjollund

Storgaard

Ernst

, et al. Impact of diurnal scrotal temperature on semen quality. Reprod Toxicol 2002; 16: 215–221.

76.

Thonneau

Ducot

Bujan

, et al. Effect of male occupational heat exposure on time to pregnancy. Int J Androl 1997; 20: 274–278.

77.

Hjollund

NHI

Bonde

JPE

Jensen

, et al. Diurnal scrotal skin temperature and semen quality. Int J Androl 2000; 23: 309–318.

78.

Skandhan

KP.

Psuedo male infertility: traditionary, customary and occupational hazards. Urologia 1999; 66: 202–204.

79.

Hamerezaee

Dehghan

Golbabaei

, et al. Assessment of semen quality among workers exposed to heat stress: a cross-sectional study in a steel industry. Saf Health Work 2018; 9: 232–235.

80.

Sheiner

Hammel

, et al. Effect of occupational exposures on male fertility: literature review. Ind Health 2003; 41: 55–62.

81.

Bonde

JP.

Semen quality in welders exposed to radiant heat. Br J Ind Med 1992; 49: 5–10.

82.

Momen

Ananian

Fahmy

, et al. Effect of high environmental temperature on semen parameters among fertile men. Fertil Steril 2010; 93: 1884–1886.

83.

Mortimer

Templeton

Lenton

, et al. Annual patterns of human sperm production and semen quality. Arch Androl 1983; 10: 1–5.

84.

Deng

Chen

Zhang

, et al. Association between air pollution and sperm quality: a systematic review and meta-analysis. Environ Pollut 2016; 208: 663–669.

85.

Skandhan

Mazumdar

BN.

High incidence of male involuntary infertility. Infertility 1982; 5: 167–174.