Young men who are obese appear to have lower sperm counts than their slimmer peers but it’s not certain whether obesity can hamper a man’s chance of becoming a father.

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A new study, reported in the journal Fertility and Sterility, has added to evidence linking obesity to poorer quality sperm.

Women are more attracted to flirtatious faces when they are at the most fertile point of their monthly cycle, according to new English research reported by the BBC.

Evolutionary psychologist Dr Edward Morrison of the University of Portsmouth asked women to rate the attractiveness of various facial expressions.

He found that women preferred flirtatious expressions when they were ovulating.

Researchers produced various facial models that were rated on a flirtatiousness scale by one group of 16 women.

English scientists claim to have created a human sperm from stem cells in the laboratory – a world first.

In a move that could eventually spell the doom of the male sex, the researchers said their work could also lead to men with fertility issues fathering children, the BBC reports.

The team who created the sperm caution that it will be at least five years before the technique is perfected, but assured that the work won't be used to ‘create humans in a Petri dish’.

Using a hands-free device such as Bluetooth headsets could affect your fertility if you leave your phone in your pocket next to your testes, warn US researchers in Fertility and Sterility.

WebMD reports that those men who leave their cellphones in their pants, or clipped on their belt close to their gonads, may be exposing them to harmful radiofrequency electromagnetic waves.

Research suggests perfumes or scented creams may cause unborn males to suffer cancer or infertility in later life, with pregnant women urged to cease using the product, the Guardian reports.

Consuming just one portion of soy every two days could be enough to lower sperm by 41 million per millilitre of semen, according to a study published in the journal Human Reproduction.

Plant oestrogens in foods like tofu, soy mince or milk may be interfering with hormone signals, say the authors.

However, an obvious control group to the study’s testing is... all the men in Asia – who eat more soy products, often every day, with no discernible negative effects to their fertility.