Climate affects the sex of the fetus

Couples living in the tropics are more likely to give birth to girls than families in temperate regions like Europe. That is the conclusion drawn from an epidemiological study published in the British journal Biology Letters.

Although published on the day of April, but the research by endocrinologist Kristen Navara of Georgie University (USA) is not a joke.

The expert collected all the statistical data provided by the CIA UK intelligence agency on the number of children both boys and girls born between 1997-2002 in 202 countries. Accordingly, the number of boys accounts for an average of 51.3% of the total number of newborns in the world, but this figure represents large differences depending on the climate of each country.

In tropical climates, the rate of male babies accounts for only 51.1% and even 50.8% for Lower Saraha (Africa) compared with 51.4% in Europe. This difference has taken into account cultural factors, such as in China or India, families who prefer to have a son, leading to a common abortion situation when the fetus is identified as a female. . This phenomenon not only occurs in Asia but also in many African countries.

The issue of "sex index" has attracted the attention of the scientific community for decades. In the 19th century, French physicist Pierre-Simon Laplace compared the data collected on the number of babies in Paris and London. By 1930, British scientist Ronald Fischer also focused on this issue.

In France, up to now, the average ratio between male and female babies is 105/100, while in China, this ratio is 120/100. Reproduction expert Bernard Jegou of the French National Institute of Health and Medical Research (Inserm) and the University of Rennes I said in wildlife or experimental animals, observations for seeing sperm reproduction in males will increase in summer rather than winter. This phenomenon involves a period of illumination and originates from the pituitary gland in the brain, which has a key role in regulating circadian rhythms by activating gamete production. The melatonin hormone secreted from the pituitary is an intermediate used to show the effect of light on the reproduction process.

Bernard Jegou commented: "When the lighting time is long, the pituitary will be more illuminated. In the laboratory, I observed that adjusting the lighting time will affect the birth of a male or female. If you keep the lights on the hamster for a long time, the shorter the time to turn off the lights, the more hamsters the female mouse will produce, which is the same for humans. "