Anecdotally I can say it has a large effect on the male brain too. The lack of sleep and time changes you. You get ruthless against time stealers and start seeing 6 hours as a nice long sleep.
Full disclosure : I've had about 8hr sleep in 3 days,two sick kids...
People underestimate the effect of extreme sleep deprivation. For the first three months of my daughter's life, we didn't sleep for more than two hours at a time. The effect was profound - I was having auditory hallucinations, was paranoid, etc. It was only after she started sleeping through the night that I understood it was due to the lack of sleep.
I experienced this too with my daughter. She had colic so we got very little sleep for 3 months straight. I thought I was going crazy due to hallucinations and paranoia. All that went away when I was able to get at least 6 hours straight sleep per night.
Detected; I reject that it's relevant to the discussion, and I'm disappointed it's the top comment. Lifestyle changes aren't relevant to the research presented in the study. What would be relevant is contrary evidence of hormonal changes in males after their spouses undergo pregnancy, or structural alterations in the brain. Of course each parent is impacted by literally taking care of an infant, but what does that have to do with one gender experiencing grey matter reductions?
You know what's super-interesting? Although it's deeply under-researched and still subject to a lot of argument, there's mounting evidence that men going through a partner's pregnancy experience significant hormonal changes as well. Papers like [1] and [2] are really preliminary (small sample sizes, etc) and don't fully agree, but both show these hormonal changes in men going through pregnancy with a partner. How much is simply the stress of a life change? How much is couvade, or "sympathetic pregnancy"? How much is evolutionarily adaptive? No one knows yet, but it's an interesting piece to the puzzle: apparently the lower testosterone, higher cortisol, and changes in prolactin and estradiol that expectant fathers experience don't have the same neuroanatomical effects as the changes women experience in pregnancy.
That is irrelevant as it is consequence of life style change. Many mothers do not change lifestyle.
This however makes me think how much of the woman change is due to the life style change which is mandatory in given situation for majority of mothers and how much is programmed.
There are cultures where the grandparents or other relatives mostly take care of the children while the mother works (some parts of China), and there are people who pay for nannies to take care of the children at night.
Twin parent here...2 years and 2 months into it, and I would really like to know the limit of this "at least 2 years", because that original brain hasn't shown itself one bit, and I'd sure like to have it back.
Full disclosure : I've had about 8hr sleep in 3 days,two sick kids...