When does the idea of 'men from Mars, women from Venus' begin? Among various differences, research results indicate that differences in the brain start from the womb. According to a study published last month in the journal 《Scientific Reports》, the differences in brain growth based on gender appear from mid-pregnancy.
A research team from the University of Cambridge in the UK tracked human brain growth from mid-pregnancy to a few weeks after birth for the first time. The researchers utilized about 800 prenatal and postnatal scan data collected from the 'Developing Human Connectome Project'.
The research team analyzed brain scan images and modeled the early developmental process not as individual snapshots but as connected trajectories. This approach is important because brain volume changes rapidly during this period. By observing growth curves over time instead of single measurements, subtle differences can be interpreted more easily.
The researchers explained, "Many studies have focused only on fetal development or newborns and infants, overlooking the very moment when the brain rapidly restructures to sustain life outside the womb. Without these continuous observations, it was difficult to determine whether gender differences appear only after birth or if they start earlier and gradually expand."
The study found that measurable differences in the way male and female brains grow appeared already after mid-pregnancy. The male brain showed a larger overall increase in volume during the developmental process. This difference was observed across the entire brain compared to females at the same early life stage.
Previous studies on fetal brain development explained that differences in brain growth based on gender were mainly observed in the late stages of pregnancy, specifically after 28 weeks. The pregnancy period is divided into three stages, with the late stage referring to the third trimester. The mid-stage typically includes weeks 13 to 27 of pregnancy. The newly published study is understood not as refuting previous explanations but as precisely defining that point earlier. In other words, the gender differences observed in previous studies during late pregnancy actually began to form in the earlier mid-stage and became more pronounced over time.
In summary, the gender differences in fetal brains should be understood as a process that accumulates gradually along different developmental paths from mid-pregnancy, rather than a sudden occurrence in late pregnancy, which is the core of this research.
The researchers stated, "This study provides an answer to the long-standing question of whether innate factors play a role in forming gender differences in the brain," and added, "This research revealed that gender differences exist in the human brain growth process during the fetal period, especially in mid-pregnancy."
They also noted, "The human brain undergoes the fastest and most complex developmental processes before and immediately after birth," and added, "Even if post-birth experiences have additional effects on gender differences, biological factors during the fetal period lay the foundation for gender differences."
