Friday, March 5, 2010

Daddy Also Gets (a little bit) Pregnant

Fatherhood Friday at Dad Blogs

Welcome to Fatherhood Friday! Forgive me folks, but this will be a little light on the funny and a little heavy on the science. Having recently experienced a few phenomena that gave me reason to consider it, I decided to do a little research on the physiological changes male partners experience during pregnancy. I figured there would be a fair amount of research available and I was able to find some interesting data, albeit less than I thought. Join me as we take a whirlwind tour of the research that I've come across that all seems to supports the thesis that, yes, Daddy also gets a little bit pregnant.

Let's first turn to a short historical account of male pregnancy sympathy, then discuss the specific physiological mechanisms for this condition. We'll follow that by turning to manifestations of this condition (including my own purely anecdotal account) and end with some speculation as to why this occurs and consider some potentially fascinating implications.

When people discuss males experiencing some symptoms of pregnancy, they tend to refer to sympathetic pregnancy, otherwise known as Couvade syndrome. "Couvade" sometimes refers to rituals certain societies conduct to have men to either act out or actually experience pregnancy-like symptoms (such as those discussed here), but I have in mind the actual physical manifestation of pregnancy-like symptoms some men report. This is typically the domain of bad 80s sitcoms, not reasoned inquires into biology. In the past, sympathetic pregnancy was only considered in the extreme (if it was considered at all) and was seen as some type of deficiency, an abnormal psychological event typically described in Freudian terms that had outward physical manifestations; it was ultimately seen as a purely psychosomatic event. New research seems to suggest that the overwhelming majority of men experience some form of pregnancy sympathy with their pregnant partners and those with the more severe forms (including those who develop distended abdomens) simply suffer from a more drastic form of the physiological changes most of us male partners experience. In short, it seems perfectly normal at least up to a certain point.

Let's now consider some of the available research on this intriguing phenomena. This article (hereafter called the Storey article, after the primary author of the study) cites an incredible number of scientific studies that verify that men experience significant hormonal fluctuations during pregnancy and after their child(ren) are born, and this hormonal change is most significant in those men who report two or more "couvade symptoms." One of the articles cited by Storey defines couvade or sympathy pregnancy symptoms in a pretty similar manner to how one would describe some of the issues that come along with pregnancy: weight gain, toothache/bleeding gums, heartburn, hemorrhoids, increased appetite, decreased appetite, vomiting, weight loss, pain, varicose veins, spontaneous nosebleeds , etc. (the list goes on, but those are the most commonly experienced conditions).

Let me clearly state that Storey admits that the study really only applies to those societies in which males have very direct and constant involvement in the pregnancy as well as in child rearing. Let me also admit that this article is a bit on the dense and somewhat impenetrable side, so I'll try to distill some of the findings down to digestible chunks. Here are a few highlights:
* Males experience significant fluctuations in prolactin production around the third trimester. This hormone is primarily associated with the production of breast milk. Males always have a certain level of prolactin production, but in the third trimester and immediately after the birth of their child(ren), prolactin production in males increases up to 20%.
* Males experience a huge dip in testosterone production right around birth of their child(ren). Storey found that they experience a 33% decrease in the first three weeks following birth. This begins to return to normal levels after four to seven weeks.
* Even when not in a birth situation, it should be noted that increased prolactin production in males almost always corresponds to a decrease in testosterone production in males (and, interestingly enough, to a decrease in estrogen production in females). Whether the exact mechanism for the decrease in testosterone is the increase in prolactin or vice-versa, or if they are carried by some common third cause is still up for debate. In other words, we know THAT this happens, but we don't exactly know HOW it happens.
* Cortisol production also experiences significant changes, increasing for both males and females immediately prior to birth. Cortisol is often associated with stress (although, from what I've read in other research, this connection is somewhat dubious). Storey found that there was a strong correlation between men who had partners who reported a significant reaction to babies crying (specifically, that they felt the overwhelming urge to nurture when they heard the noise) and an elevated cortisol level. Among those males who had partners who did not report feeling a strong urge to nurture their crying children, the cortisol level barely peaked or didn't increase at all. The real kicker here: the females who reported great concern over their baby crying had higher cortisol levels, and their male partners had correspondingly elevated cortisol levels. Furthermore, male cortisol levels among all male participants increased an average of 50% over pre-pregnancy levels. This last finding may not be all that significant, however, because cortisol levels tend to increase in any stressful situation.
* The spectrum of male hormonal changes and the reports of sympathy pregnancy symptoms follow something of a lopsided "U" pattern. They start out pretty high in the first trimester, dip strongly in the second, then peak highest in the third and immediately after birth. My speculation: consider the parallel to women and their reports of seems pretty darn similar to me. Please note that I'm speculating here!

Another article discusses weight gain in male marmosets and tamarinds. This project seems to point to other causes for weight gain among partners of pregnant people than simply giving in to temptation. Note that I don't think that's what is going on in my case. I've put on over 10 lbs since Amanda found out she was pregnant, but I think that's due to my inability to resist chocolate! However, some men have reported maintaining identical diets to what they ate prior to their partners' pregnancy but still gaining significant weight.

A couple other studies, such as this one, have looked at male parent brain structures. Among first time marmoset fathers, researchers observed a substantial increase in dendrite connections in the prefrontal cortex upon birth of their offspring. What does this mean? Well, the prefrontal cortex is the part of the brain that affects planning, proper social relations, decision making, etc. so more connections suggests greater ability in these areas. While I did find an article that contends that this extends to human fathers (the article I cited merely postulates that this is the case), I can't find what I did with the blasted thing. As such, we're left to speculate as to whether or not this situation can be extended to us hairless primates.

A study by Sandra J. Berg (and others) offers some additional data of interest. This study was essentially a follow-up of the Storey study and it largely confirmed the findings of the earlier study while also going a step or two beyond. The Berg study found that:
"* The testosterone concentration was significantly lower in the overall sample of 23 dads than in the 14 control subjects [non-fathers].
* Cortisol concentration was significantly lower in dads than in the control group [please see note below].
* Dads had a higher proportion of samples with detectable estradiol [estrogen] concentrations."

Please note that the second point in the quote above does not contradict Storey's findings. Storey was discussing men who were partners of pregnant women. Cortisol actually builds in women when they're pregnant and is heavily involved in the onset of labor (it's at its highest at that point), thus the increase during pregnancy in the male partner seems to parallel the increase in the pregnant female partner. Berg's study considers people who are new fathers, not those experiencing childbirth. Let it be known that I find the cortisol issue the most questionable of all the issues discussed herein, but that may be because I'm not entirely clear on the nature of cortisol and its role in various biological processes. Any biologists in the house?

As discussed before, in the past men were viewed as somehow psychologically damaged or at least misguided if they expressed pregnancy sympathy. Now we've come to see that there are some underlying physiological changes that might be the causal agent of these outward physical expressions. That does not mean that all pregnancy sympathy-like symptoms ARE actual outward expressions of internal hormonal changes. Rather, I just want folks to be aware that men DO often experience hormonal fluctuations. Here's a pretty interesting article that provides some accounts of men experiencing these symptoms, and here is another.

As for myself, I have no idea if any of my "symptoms" are manifestations of hormonal changes, the result of some type of psychological condition, etc. What I do know, however, is that my teeth have been killing me for the past week or so and my gums have been bleeding like crazy, something that hasn't happened to me since I had a particularly nasty tooth extracted a few years ago. I've also gained over 10 pounds, but as I stated earlier this is due to an inability to resist the siren call of chocolate. I've also been...well, rather moody lately with no idea as to why. I try my best to suppress this, though.

Let me briefly divert the discussion to two semi-related topics. That male and female human beings are very similar is pretty well established. I mean, ask most partners if they understand their significant other and they're likely to express frustration and/or amusement, but on a basic biological level we're remarkably in line. An additional piece of this similarity can be found in, of all places, our nipples. We're pretty unusual in the mammal world in that we have very similar structures under the skin that's under our shirts. Male humans actually have perfectly intact mammary glands, while the males of many other species have either vestigial nipples and/or glands or no nipples at all. Only one male animal in the world spontaneously lactates, that being the Dayak Fruit Bat. However, men can and do lactate, typically as the result of some type of medical condition or treatment (and it happens in babies of both sexes often enough that it has a terrible sounding name: witch's milk). Remember how I mentioned that prolactin is directly related to lactation and how men produce a small amount at all times but a larger amount when their child(ren) are born? Here's something crazy to think about in relationship to that: there was a long-standing disagreement in the medical community as to whether or not the average male could lactate given the right conditions. One camp held that only males with already elevated prolactin levels (either naturally or with hormone supplements) could lactate while the other camp contended that any male could with proper stimulation. It turns out they were both right. The act of nipple stimulation in males actually increases prolactin production, and many males can makes themselves lactate given enough stimulation once the prolactin production reaches a sufficient level. Don't worry, folks. I love non-traditional gender roles, but this one might go a step beyond what I'm comfortable with doing myself. That said, I certainly wouldn't judge a man for engaging in the activity if he and his partner thought it was the best move for their offspring. There have been numerous reports of men doing this exact thing. Pretty intriguing, no?

Speaking of non-traditional gender roles, let's take the biggest possibility head-on: male pregnancy. While this sounds like the start of a joke (or the premise for an especially terrible movie), it's not. Researchers seem to agree that a male human could certainly become pregnant through IVF (in vitro fertilization) followed by implantation somewhere in the abdomen. A uterus is not strictly necessary for pregnancy, as illustrated in the unfortunate circumstances of ectopic pregnancies. But from a couple modern cases, given just the right set of conditions, we can see that a non-uterine pregnancy can be carried at least to the age of viability. But, as is well known about ectopic pregnancies, in almost every case they're life threatening to the mother and often don't lead to viable babies. Basically at this point it's quite possible that a man could carry a fetus (most advisably a male as carrying a female baby would require extensive hormone therapy), but the male host would most certainly die in the process of a modified cesarean extraction because the placenta would intermix with whatever organ(s) it came into contact with, causing massive and irreparable hemorrhaging. Advances in science suggest that either the growth of fetal tissue could be appropriately redirected to non-vital organs, or there's the more drastic (and questionable) measure of uterine transplants.

Ok, back to the original topic. The specific mechanism for all this interesting pregnant partner hormonal shuffling is still unknown. It has been speculated that pheromones somehow influence this process, a very possible but unconfirmed idea. It's also possible that proximity to pregnant females and/or newborn infants trigger hormonal changes similar to how mechanical stimulation of male nipples increases prolactin production but this, too, has been insufficiently studied. Another study by Berg & Wynne-Edwards suggests that there's no specific correlation between the fluctuations males experience and the fluctuations their female partners experience, though there is still strong evidence that hormonal changes DO occur in men on the birth of their child(ren). This actually pushes a "proximity theory" to the forefront, but only as an intuitive explanation.

Future research will hopefully involve folks like stay-at-home dads, gay couples with children, adoptive parents, fathers who actually dislike the idea of having children, and single fathers with full custody. Perhaps these folks could give us greater insight into the way we males--on a biological level--prepare ourselves to become fathers.

All of this begs a simple question: why? Why would males have their hormonal patterns change at birth? Being someone who is more or less a biological reductionist (meaning I think just about everything can be explained in simpler, more basic biological terms, such as our behaviors reducing down to a set of biochemical responses to stimuli), it seems evident that we males have our testosterone levels dip because we need to nurture at that point and testosterone tends to make us aggressive and competitive. Here's an example of a pretty carefully constructed reductionist view of couvade symptoms. If the story of testosterone reduction giving rise to nurturing behaviors in males holds, this would have an obvious evolutionary advantage. But reductionism is pretty far from a perfectly provable thesis (though I think it's defensible), so I have to shrug my shoulders at this point and say that we may not know why, exactly, and we may not even know exactly how, but we do know THAT this happens, and isn't it pretty damned fascinating?

I'd love to hear thoughts on this, especially from anyone who would contend that they did or did not experience (for men) or see (for the partners) any pregnancy sympathy symptoms. Hopefully you found this interesting; if not, sorry about that! I'll be back next and hopefully I'll bring the funny with me.


Jason Wm Harris said...

Well done Kevin. This go-around is the second time we've done this, and I've gained weight both times.

Jason Wm. Harris

Daddy Files said...

I have no doubt this was well written and comprehensive. But I only got through about half of it before skipping to the end.

I recognized my wife's pregnancy as an opportunity to eat all the ice cream and tons of fast food she was craving, right alongside her. That's the extent of my scientific contribution to this particular subject area.

I'm useless.

SAHD PDX said...

uhhh thanks for the thorough work done here

Reservoir Dad said...

I'm feeling a tad bloated and ads on the TV with children in them make me cry in a sorta happy way.

Zach Rosenberg said...

Whew. Just read all this. Interesting stuff. Glad you had commented on our story on - totally interesting topic, especially in a society where we generally assume all fathers have no real hormonal connection with their babies (thus the popular consensus that men can easily walk away from a baby, women can't).

kmberry said...

Thanks for the comment, Zach! Sorry I was so long winded. I spent a few days "researching" instead of, you know, doing anything remotely productive. I figured I should at least squeeze a post out of my complete lack of productivity. Funny how you said similar things in far shorter posts. I think I could (read that: should) learn something from you in this respect! By the way, I'm glad I found your site. Great stuff!

Zach Rosenberg said...

Thanks man - that means a lot! And believe me - I'm known to be long-winded. But the shorter stuff misses details. Your post was long but definitely worth the read!