Correlation is not causation but a new study in the journal Fertility & Sterility found that mothers who experienced an increase in weight from the beginning of the first pregnancy to the beginning of the second pregnancy may be slightly more likely to give birth to a baby boy during their second pregnancy.
A slightly greater number of males than females are born worldwide every year but in recent decades there has been a decline in the ratio of male to female newborns in several industrialized countries, including Canada, Denmark, England, Germany, Japan and the United States.
That may be the result of nutrition, say researchers from Harvard School of Public Health (HSPH) and Karolinska Institutet in Stockholm, Sweden.