Published Oct 06, 2026 | 5:00 PM ⚊ Updated Oct 06, 2026 | 5:00 PM
The control rats had an average sperm concentration of 175.5 million per millilitre. This fell to 119.2 million in the 3.5 GHz group and 131.3 million
Synopsis: A study in the Indian Journal of Medical Research found that male rats exposed to 3.5 GHz and 24 GHz radiofrequency signals for seven hours a day over 60 days had lower sperm concentration and motility, along with differences in pregnancy and birth outcomes. The researchers recorded stillbirths and abnormalities in the 3.5 GHz group, while the 24 GHz group had a lower pregnancy rate and birth weights, but said the findings cannot be directly applied to humans. The study calls for larger research into sperm DNA damage, oxidative stress and reproductive outcomes.
Male rats exposed to 5G radiofrequency signals for seven hours a day over 60 days produced significantly fewer and less motile sperm, while their offspring showed differences in pregnancy and birth outcomes, according to a study published in the Indian Journal of Medical Research.
Researchers from Universiti Kebangsaan Malaysia tested two frequencies used in 5G technology—3.5 GHz and 24 GHz—on 18 male Sprague Dawley rats. The animals were divided equally into three groups: a control group, a group exposed to 3.5 GHz signals and another exposed to 24 GHz signals.
The study found significant reductions in sperm concentration and motility in both groups exposed to radiofrequency electromagnetic fields (RF-EMF).
The researchers also recorded differences in reproductive outcomes. The 3.5 GHz group had 10 stillbirths with abnormalities. The 24 GHz group recorded a lower pregnancy rate and lower birth weights. The authors said the results cannot be directly applied to humans.
“These findings may inform potential risks to male reproductive health from human exposure to RF-EMF-emitting devices at similar frequencies. However, translation to human reproductive health should be approached cautiously, as the real-world exposure scenarios are complex and remain challenging to replicate accurately in controlled experimental settings,” they wrote.
Dr Raghuveer Karne, Consultant Andrologist at Oasis Fertility, who was not involved in the study, told South First that the findings are important but do not warrant alarm.
“This study is a useful addition to the evidence base and reinforces the need for well-designed human research to understand whether similar effects occur under real-world exposure conditions,” he said.
Also Read: Fewer than 1 in 4 people with diabetes in India sustain diet advice for six months, experts say
The control rats had an average sperm concentration of 175.5 million per millilitre. This fell to 119.2 million in the 3.5 GHz group and 131.3 million in the 24 GHz group. Both reductions were statistically significant.
The difference was larger for sperm motility. In the control group, 75.6 percent of sperm were motile. The figure fell to 43.6 percent among rats exposed to 3.5 GHz and 27.3 percent among those exposed to 24 GHz. Sperm viability did not change significantly.
In simple terms, the exposed rats continued to produce viable sperm, but a smaller proportion of the sperm were moving.
“From an andrology perspective, sperm concentration and motility are important indicators of male reproductive potential,” Dr Karne said.
The authors said the findings were consistent with earlier research on radiofrequency electromagnetic fields.
“This study found a significant decrease in both sperm concentration and motility following exposure to 3.5 GHz and 24 GHz, consistent with previous studies,” they wrote.
Also Read: Medicine Nobel 2026: How a light-sensitive algae protein gave scientists a brain control switch
All four females that successfully mated with control males became pregnant. The same was true of all six females paired with males exposed to 3.5 GHz. In the 24 GHz group, five of the six females became pregnant, giving a pregnancy rate of 83.3 percent.
The control group produced 38 pups, all of which were live births. The 3.5 GHz group produced 63 pups, including 10 stillbirths, giving a live birth rate of 84.13 percent. The 24 GHz group produced 46 pups, all of which were live births.
The stillborn pups in the 3.5 GHz group had extensive abnormalities, including deformities of the head and body. Two also had abdominal haematomas.
Pups in the 24 GHz group weighed 6.707 grams on average at birth, compared with 7.312 grams in the control group. The difference was statistically significant.
The researchers found no statistically significant difference in the sex ratio of the offspring.
The two frequencies produced different reproductive outcomes. The 3.5 GHz group had a 100 percent pregnancy rate despite poorer sperm quality, but recorded stillbirths and abnormalities. The 24 GHz group had a lower pregnancy rate and lower birth weight, but no stillbirths.
The researchers said rodents’ high sperm production capacity could explain why conception remained possible despite reduced sperm quality.
“Thus, the functional reserve of sperm production can sustain conception despite increased cell apoptosis or DNA damage,” the authors wrote.
For the 24 GHz group, the researchers suggested that higher-frequency exposure “may interfere with early embryonic development, leading to failed conception despite the presence of sperm or impair foetal growth.”
Overall, they described the findings as suggesting a “differential negative impact on pregnancy outcomes” following mating with exposed males.
Also Read: The real millet story: ‘Nutri-cereals’ polished off nutrients, high on glycaemic impact
The researchers discussed thermal and non-thermal mechanisms that could explain the changes in sperm, but did not directly test them.
For 3.5 GHz exposure, they suggested that localised heating could raise testicular temperature and interfere with sperm production. Oxidative stress and mitochondrial dysfunction could also contribute to reduced sperm motility, they said.
For 24 GHz millimetre waves, penetration into tissue is shallower. The researchers nevertheless suggested that localised heating, oxidative stress and changes in cellular signalling could produce biological effects.
The study did not directly measure sperm DNA damage or oxidative stress in the testes.
“Although sperm DNA damage was not assessed in this study, increased sperm DNA fragmentation has been reported in microwave studies,” the authors wrote.
They called for future studies to directly measure oxidative stress and sperm DNA fragmentation alongside pregnancy outcomes.
Also Read: ‘Buddy, I’ll be looking out for you’: Keralam puts students at heart of a new health network
The experiment involved only six male rats in each group. The researchers were also not blinded to the group assignments and acknowledged that this “may introduce observer bias in outcome assessment.”
The exposure conditions also do not represent everyday human exposure. The rats were exposed for seven hours a day for 60 days under controlled conditions, using specific frequencies and devices.
Dr Karne said this distinction is critical.
“However, these findings should be interpreted responsibly. This was an animal study involving only 18 male rats, with exposure for seven hours a day over 60 days. The exposure conditions cannot be directly equated with everyday human exposure to 5G devices or networks,” he said.
The researchers also emphasised the limits of applying the animal findings to humans.
“Translation to human reproductive health should be approached cautiously,” they wrote, adding that real-world exposure scenarios are difficult to reproduce in controlled experiments.
Dr Karne said the study should be treated as a prompt for further research, not as proof of harm in humans.
“What makes the research particularly relevant is that it highlights an area that warrants further investigation rather than establishing a direct cause-and-effect relationship in humans,” he said.
The authors recommend larger studies, improved mating designs and experiments that vary exposure between male and female animals. They also want future research to directly examine oxidative stress and sperm DNA fragmentation.
“Future studies should also employ mating designs that vary exposure between partners and assess their effect on the pregnancy and offspring outcomes. Besides, a larger sample size would also be beneficial to identify subtle differences between the 3.5 GHz and 24 GHz exposure conditions,” the authors wrote.
(Edited by Dese Gowda)
