The brains of first-time fathers may shrink, reveals new study

First-time fathers may lose a percentage or two of cortical volume in the brain following the birth of their child, research released this week showed. The study, first published in the journal Cerebral Cortex, echoes research that found mothers' brains changed during their first pregnancies too.

These changes to fathers' brains mainly occurred in an area of the brain known as the 'default mode network,' which is associated with parental acceptance and warmth.

Although this may sound like a negative thing at first, it can indeed indicate a refinement of the brain that makes connecting with a child more significant and natural.

To reach this conclusion, the researchers studied the magnetic resonance imaging (MRI) information from 40 heterosexual first-time fathers, half of whom were based in Spain and half of whom were based in the United States, and a control group of seventeen men without children based in Spain.

The research was a collaboration between researchers at the Instituto de Investigación Sanitaria Gregorio Marañón in Madrid, the University of Southern California in Los Angeles, and the Autonomous University of Barcelona.

The fathers in Spain underwent brain scans before their partners' pregnancies and then again a few months after their child’s birth. Those in the U.S. undertook scans during the mid-to-late stages of their partners' pregnancies, and then again seven to eight months post birth.

Brain plasticity and the visual system

The researchers then compared those results against the control group and found signs of brain plasticity in their cortical gray matter, the area responsible for social understanding, and pronounced reductions in the visual system's volume.

“We found overlapping trends of cortical volume reductions within the default mode network and visual networks and preservation of subcortical structures across both samples of first-time fathers, which persisted after controlling for fathers’ and children’s age at the postnatal scan,” wrote the researchers in their study.

“This study provides convergent evidence for cortical structural changes in fathers, supporting the possibility that the transition to fatherhood may represent a meaningful window of experience-induced structural neuroplasticity in males.”

The research echoes conclusions found by another team in 2016. A first-of-its-kind study was released that revealed that the architecture of women's brains changes dramatically during their first pregnancies by shrinking gray matter in areas involved in the processing and responding to social signals.

"We certainly don't want to put a message out there along the lines of 'pregnancy makes you lose your brain,'" Elseline Hoekzema, a neurologist at Leiden University in the Netherlands and the study's principal author, told Science.org when the study was first published.

"Gray matter volume loss can also represent a beneficial process of maturation or specialization."

Both areas that were affected by the womens’ pregnancies were those that can help fathers connect more profoundly and efficiently with their newborn infants.

The results indicate that not only women have an increased tendency to change in order to adapt to their infant’s arrival. Men are equally capable of this important alteration and can therefore play just as important a role in their children's lives.

Study abstract:

Emerging evidence points to the transition to parenthood as a critical window for adult neural plasticity. Studying fathers offers a unique opportunity to explore how parenting experience can shape the human brain when pregnancy is not directly experienced. Yet very few studies have examined the neuroanatomic adaptations of men transitioning into fatherhood. The present study reports on an international collaboration between two laboratories, one in Spain and the other in California (United States), that have prospectively collected structural neuroimaging data in 20 expectant fathers before and after the birth of their first child. The Spanish sample also included a control group of 17 childless men. We tested whether the transition into fatherhood entailed anatomical changes in brain cortical volume, thickness, and area, and subcortical volumes. We found overlapping trends of cortical volume reductions within the default mode network and visual networks and preservation of subcortical structures across both samples of first-time fathers, which persisted after controlling for fathers’ and children’s age at the postnatal scan. This study provides convergent evidence for cortical structural changes in fathers, supporting the possibility that the transition to fatherhood may represent a meaningful window of experience-induced structural neuroplasticity in males.