Eating to Birth Sons
A British study has shown for the first time that a mother's diet has an effect on the sex determination of her children. The universities of Exeter and Oxford have proven that the consumption of high-energy foods around the time of conception prepares the way for the birth of a son. The findings of this study may help to explain why the birth rate of boys has been falling over the past forty years in industrialized countries such as the UK, the US, and Canada.
Participating in the study were 740 women experiencing a first pregnancy. The women did not know the sex of their fetuses and were asked to keep a record of their eating habits before and during the early stages of their pregnancies. Participants were then split into three groups based upon the number of calories they had consumed per day prior to conception.
Of the women in the group who had the highest calorie intake at conception, 56% had sons as compared with 45% in the group who consumed the lowest number of calories. The women who gave birth to sons tended to have a higher quality diet with a wider ranger of nutrients. Women who ate breakfast cereals also had a higher rate of male-producing births.
Lead author of the report, Dr. Fiona Mathews of the University of Exeter, said, "This research may help to explain why in developed countries, where many young women choose to have low calorie diets, the proportion of boys born is falling."
The results of the study mimic what scientists already knew to be true about animals: a mother who has more resources at her disposal produces more sons. This phenomenon has been seen in invertebrates, horses, cows, and in some species of deer. The scientific community postulates that this apparent link between resources and male children is connected to evolution and the drive to produce descendants.
Dr. Mathews explains that while males of most species can father more children than females, there is a strong influence of the size or status of the father, with poor males sometimes lacking the ability to breed. Females breed with greater consistency. That means that if a mother has many resources, for instance, the ability to consume more calories, it may make more sense to invest in producing a son, because this, in turn, brings more grandchildren. Comments Mathews, "…in leaner times having a daughter is a safer bet."
Skipping Breakfast for Girls
The sex of the child depends on the sperm issued by the father, however, mothers appear to be able to provide conditions that predispose insemination by male or female sperm, depending upon maternal diet. While the mechanism is not yet understood in mammals, it is known from IVF research that high levels of glucose encourage the growth and development of male embryos while female embryos are inhibited. Skipping breakfast depresses glucose levels and may be interpreted by the human body as an indication of poor environmental conditions and the low availability of food.