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The chances of a woman conceiving a male or female child very subtly change depending on when in her cycle she conceives (Picture imagined by Meta AI)
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HEALTH - A British mathematician has unveiled a fascinating sex "hack" that could influence the likelihood of conceiving a baby boy. Professor Hannah Fry, a renowned academic and television presenter, recently took to Instagram to explain a curious trend known as the "returning soldier effect," which has been linked to spikes in male births following major world events, such as wars.
Professor Fry pointed to historical data from England and Wales, showing noticeable peaks in the ratio of baby boys born after the First and Second World Wars. "You've got some really definite peaks—one in 1919 just after the end of the First World War, and another in 1945 after the Second World War," she explained.
According to Professor Fry, this phenomenon is driven by a combination of social factors and a biological quirk. After wars, soldiers returning home often lead to an increase in sexual activity, raising the chances of conception. This heightened frequency of sex means women are more likely to conceive earlier in their fertile window, which, in turn, slightly increases the likelihood of having a boy.
"The chances of a woman conceiving a male or female child very subtly change depending on when in her cycle she conceives," Professor Fry said. "Conceiving slightly earlier makes it ever so slightly more likely that she'll have a baby boy."
Experts theorize that hormonal or acidity levels in a woman's body fluctuate during her cycle, altering the cervical environment. These changes may favor sperm carrying the Y chromosome, which determines male sex. Other studies suggest that a slight increase in female embryo mortality compared to males could also contribute to the imbalance.
However, Professor Fry cautioned that the method is not foolproof. On an individual level, the increased chance of having a boy is minimal. "When you scale up to the size of a population, this becomes a pattern that becomes really clear," she said.
Interestingly, the "returning soldier effect" isn't limited to wartime. A similar spike in male births was observed in Britain in 1973 during an energy crisis, when many people worked fewer days a week. "I think we now know what everyone in Britain was doing during their three-day week," Professor Fry joked.
While the effect is real, it's worth noting that slightly more boys are born than girls even during normal periods—typically around 104 boys for every 100 girls. This imbalance evens out over time, as slightly more boys tend to die before reaching adulthood due to accidents or developmental issues.
Source: Daily Mail
