It's unfortunate that the link that made the front page here is to the BBC article rather than the NYTimes article [1] on the same study, as the NYTimes article much more clearly addresses a number of the points brought up by commenters here today. The NYTimes article briefly mentions other non-pregnancy related studies on the "pruning" of grey matter. One place to get a bunch of citations for studies on synaptic pruning is in the lit review of [2], since the NYTimes article itself doesn't have a citation for synaptic pruning research in adolescents. However, the NYTimes article does link to [3], an article about spontaneous theory of mind and synaptic density in 18-26 year olds. It looks at a this group of people not by age but by performance on theory of mind tasks, examining the relationship with structural MRI data from the participants. This sheds some light on efficiency and good performance on theory of mind tasks and the neuroanatomy of a person. I think for most HNers taking out thinking about pregnancy and looking at this study first would be useful in understanding the results -- we've all got a lot of preconceived notions about the effects of pregnancy that make it hard to think about the results of the study rationally.
Thanks for making this point, especially with regards to pregnancy being a loaded discussion topic.
In the original study I found it very interesting that the authors drew parallels between the "maturation" of a new mother's brain (grey matter reductions) and the brains of adolescents undergoing pregnancy. If this study replicates, I would love to see followup studies exploring measures of narcissism, time management, executive functioning and facial recognition over time in women shortly before, during and after pregnancy (and perhaps even two years afterwards). These are all areas in which adolescents experience significant variations in functioning when compared to the general population, and there could be a lot of fertile ground here.
One other thought that strikes me is how the grey matter alterations could potentially impact teenage mothers. If the mother's brain has not left adolescence by the time she experiences pregnancy, it would be interesting to see how the grey matter alterations differ, considering the authors' comparison.
Fertile ground... :) Moving on, agreed on follow-up studies. A study similar to this one looking at adolescent moms, non-moms, dads, and non-dads would be very interesting as well. After all, if a teen guy is undergoing similar pruning, what does that mean for his experience of a partner's pregnancy? Disentangling social factors from neuroanatomical changes in teen parents would be very hard, though, in societies where teen pregnancy is unusual and has big economic impacts. Might be easier to do someplace where it's more usual.
[1] http://www.nytimes.com/2016/12/19/health/pregnancy-brain-cha... [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2475802/ [3] https://scan.oxfordjournals.org/content/10/3/327.abstract