Tuesday, October 26th 2010
Just a quick link I want to share today to Martin Robbins’s blog The Lay Scientist over at The Guardian. He has a guest post written by @naomimc that describes, more elegantly than I have, the importance of reproductive choice. Entitled “Where are the women in the ‘population control’ debate?” her post demonstrates how the conversation around population control, particularly in circles devoted to the ecological impact of human populations, seems to be devoid of women, or at least controlled by men.
One of my favorite passages is here:
The green movement is often, wrongfully, accused of misanthropy. “They care more about trees than people”, screech the professional oppositionists. But the obsession with population control by a minority of greens opens them up to very legitimate accusations of authoritarianism, ‘classism’ (i.e. it’s the poor we want to stop having babies) and gender-blindness. It is a paradigm dominated by elite men which spectacularly misses the point and ignores the evidence that actually protecting sexual and reproductive rights and empowering women to control their own fertility results in lower birth rates and importantly, lower death rates.
No one who works in maternal and reproductive health talks of ‘population control’. For historical and contemporary reasons it is associated with eugenics, China’s one-child policy, forced sterilisation and forced abortion. These morally abhorrent examples might be dismissed as extremes but they are simply the results of a way of thinking about reproduction which is coercive and rejects individual rights as fundamental to public policy. (my emphasis)
Go read the post.
Monday, October 25th 2010
I polled my Twitter followers recently to find out what they wanted me to cover, and heard back a resounding “CONTRACEPTIVES!” So first I am going to re-post a series I wrote on my lab blog in July of 2009, with significant editing and updating. I think after these reposts I’ll have a better idea of where it would make sense for me to contribute more, if at all. This is post one of five.
I am not a medical professional. I am a PhD, not an MD, so this is not medical advice. And in fact, I am quite sure there are anthropologists out there who do not share my opinion, so this is not even anthropological advice. This is just one person’s perspective on a medication so pervasive few people even think of it as the serious prescription that it is.
Hormonal birth control has been around for many decades, and has seen many improvements, reductions in dosage, and different ways of accessing the medication, from a shot, to a patch, a ring or a pill. Hormonal birth control is used off-label for mood stabilization and acne, and increasingly these contraceptives are also approved for these non-contraceptive purposes. You’ve probably seen the ads of skinny-armed women punching at “irritability” and “bloating” in bubble letters before them with a girly rendition of “We’re not gonna take it” in the background. You’ve seen the slightly more “empowered” ads that have cropped up recently regarding the hormonal contraception that you can take continuously to avoid your period, where far stronger women are staring right into the camera and daring you to doubt their decisions.
I worry about health and safety issues related to hormonal contraceptives when I see these ads, because they are 1) focusing on the non-birth control aspects of the drug in order to increase the number of consumers and 2) trying to frame the debate about contraception with a watery version of “choice” feminism. However, how one feels about a commercial is not a good enough reason to dismiss a medication used by a huge fraction of reproductively aged women in the US. I was recently annoyed by a Tylenol ad, but I give my daughter acetaminophen when she has a very high temperature (not when she has a mild one — but that’s a whole other issue!). I am able to get off my high horse, folks, and I’d like to do that to discuss some recent evidence around hormonal contraception. This post will cover contraindications and side effects for hormonal contraceptives. The other posts will cover variation in menstrual cycling; population variation and environment; hormones, behavior and cognition; and non-hormonal contraceptive options.
Contraindications
If you read the packaging and/or you have a doctor worth his/her salt, you know if you have high blood pressure, a history of blood clots or liver dysfunction, you should not take hormonal contraception. End of story, and don’t try to get around it.
But do you know that if your BMI is over 25 you are at an increased risk of unintended pregnancies? The dosage for hormonal contraception was designed for average to low-average weight women from developed countries (the issue of developed versus developing countries will be important in later posts). Brunner Huber and Hogue (2005) found that contracepting overweight and obese women had twice the odds of an unintended pregnancy compared to normal weight women. The authors surveyed women after they had given birth and asked if the pregnancy was intended or unintended, and whether the individuals had used contraception or not. Among contracepting women, the number of overweight and obese women with unintended pregnancies was much higher than those with intended pregnancies. Further, they cite a convincing literature and provide a credible mechanism for why overweight women tend to have reduced efficacy on hormonal contraceptives. Burkman et al (2009) recently found similar results, but the relationship was not quite statistically significant. The results do seem to vary somewhat with which contraceptive is being tested. But with the average American woman’s BMI at 28, it seems as though today’s oral contraceptives may not be effective for a majority of our country’s population.
There are two other major issues to consider regarding the effects of hormonal contraceptives on health. The first is that hormonal contraceptives negatively impact bone mineral density. Last year, one of my undergrads Emily Marzolph wrote a wonderful Honors paper for me entitled “Moderate changes to bone mineral density due to hormonal contraceptives during adolescence may undermine wide array of skeletal mass diversity.” In her literature review, she found significant evidence that hormonal contraceptives, particularly the progestin-only injection Depo-Provera, lower bone mineral density rates (e.g., Cromer et al 2005, Prior et al 2001). However, to put these results in context, Emily also looked at what we know of interpopulational variation in bone mineral density; this turns out to be quite significant as well. Analyzing these data qualitatively, it appears that the reduction in bone mineral density caused by hormonal contraceptives is still within the range of variation seen across populations (Arabi et al 2004, Hou et al 2007). Here’s a free dissertation topic for you: someone ought to do a meta-analysis of this literature, or a cross-populational analysis of new data, that examines the differential effects of ethnicity, environment and hormonal contraceptives on bone mineral density! Who knew you could get free dissertation advice from a blog?
The second health issue I want to mention is the potential increase in systemic inflammation with the use of hormonal contraceptives (one of my other undergraduates, Katherine Tribble, found this article for our lab’s weekly journal club). Morin-Papunen et al (2008) looked at women at thirty one years of age in the Northern Finland Birth Cohort, born in 1966. They grouped these women into levonorgestrel-releasing intrauterine device (IUD) users, oral contraceptive users, and no hormonal contraception use. Morin-Papunen et al (2008) found oral contraceptive usage was correlated with increased C-reactive protein concentrations — this is a biomarker for inflammation that is associated with cardiovascular disease. Compared to IUD users, oral contraceptive users also had more insulin resistance, higher blood pressure, raised lipids and insulin levels, despite having a smaller waist and lower waist-hip ratio (a larger waist or higher waist-hip ratio is often associated with these results). Further, most of these results actually strengthened when factors like BMI, household income, and alcohol consumption were controlled for. Another interesting point, third generation hormonal contraceptives, which are lower concentrations of synthetic hormones than the second generation, actually had higher serum levels of insulin, CRP, total cholesterol and other lipids, compared to users of second generation contraceptives.
So in addition to the factors you already knew about, you may want to avoid hormonal contraceptives if your BMI is over 25 and are using them for contraception; or, if you are already at risk for osteoporosis or cardiovascular disease (or want to reduce your risk for these things).
In the second post, I’ll discuss what it means to have a normal menstrual cycle, and how this relates to the prevalence of hormonal contraceptives.
References
Arabi, A., Nabulsi, M., Maalouf, J., Chouchair, M., Khaliffe, H., Vieth, R., & Elhajjfuleihan, G. (2004). Bone mineral density by age, gender, pubertal stages, and socioeconomic status in healthy Lebanese children and adolescents Bone, 35 (5), 1169-1179 DOI: 10.1016/j.bone.2004.06.015
Brunner Huber, L., & Hogue, C. (2005). The Association Between Body Weight, Unintended Pregnancy Resulting in a Livebirth, and Contraception at the Time of Conception Maternal and Child Health Journal, 9 (4), 413-420 DOI: 10.1007/s10995-005-0015-5
Burkman RT, Fisher AC, Wan GJ, Barnowski CE, & LaGuardia KD (2009). Association between efficacy and body weight or body mass index for two low-dose oral contraceptives Contraception, 79 (6), 424-427.
Cromer BA, Lazebnik R, Rome E, Stager M, Bonny A, Ziegler J, & Debanne SM (2005). Double-blinded randomized controlled trial of estrogen supplementation in adolescent girls who receive depot medroxyprogesterone acetate for contraception. American journal of obstetrics and gynecology, 192 (1), 42-7 PMID: 15672001
Hou YL, Wu XP, Luo XH, Zhang H, Cao XZ, Jiang YB, & Liao EY (2007). Differences in age-related bone mass of proximal femur between Chinese women and different ethnic women in the United States. Journal of bone and mineral metabolism, 25 (4), 243-52 PMID: 17593495
Morin-Papunen L, Martikainen H, McCarthy MI, Franks S, Sovio U, Hartikainen AL, Ruokonen A, Leinonen M, Laitinen J, Järvelin MR, & Pouta A (2008). Comparison of metabolic and inflammatory outcomes in women who used oral contraceptives and the levonorgestrel-releasing intrauterine device in a general population. American journal of obstetrics and gynecology, 199 (5), 5290-2147483647 PMID: 18533124
Prior JC, Kirkland SA, Joseph L, Kreiger N, Murray TM, Hanley DA, Adachi JD, Vigna YM, Berger C, Blondeau L, Jackson SA, & Tenenhouse A (2001). Oral contraceptive use and bone mineral density in premenopausal women: cross-sectional, population-based data from the Canadian Multicentre Osteoporosis Study. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 165 (8), 1023-9 PMID: 11699697
Thursday, October 21st 2010
The “Around the Web” series highlights informative websites, and also targeted blog posts and news articles, relevant to the courses I teach. This semester I teach Anth 143: Biology of Human Behavior, an introductory-level course that covers the basics of evolution, behavioral biology, and the interaction of biology and culture. My hope is that these posts are useful not only for my current students, but other people hoping to gain background or insight into these topics.
This week I spent some time on things like Meaney’s mice and cross-fostering experiments, as well as 2D:4D digit ratios and prenatal hormone concentrations, as a way to get at how our development impacts behavior. I also discussed some of the main hypotheses regarding why childhood evolved in humans, since it’s a unique life stage. And as always, I’ll throw in a few random links at the end that I just think you should be reading.
Meaney’s mice
Michael Meaney isn’t just known for his cross-fostering experiments (like those described in Crabbe and Phillips 2003); they are part of a broader research program to understand stress and behavior. Here are a few stories about his other work, which is also relevant to this week’s material.
Here’s an interesting article from the Dana Foundation on recent advances in the genetics of psychiatric disorders. If you scroll your way down, however (or just CTRL-F “Meaney,” to make it easy), the author reviews two interesting pieces of research from Meaney’s lab on both rodents and humans, and the impact of poor care in childhood. I hadn’t read anything on the human work before — his lab group looked at the brains of suicide victims with and without known histories of child abuse, and found notable differences. Sad, but important work.
The other link also covers Meaney’s rodent work. In both cases, they describe work that shows how stress is modulated in rodents who were groomed and licked by their mothers. It seems as though positive, caring behaviors have a positive impact on the stress response.
What do your fingers say about you?
We talked about digit ratios and prenatal hormones this week. I showed my class some good evidence, and I showed some graphs that looked like someone drew a regression line through a sneeze. I found a blog that weirds me out a little bit — someone actually has a blog just about digit ratios. And of course, the reviews of the literature are that digit! ratios! tell us! about! our! kids! There’s no point to parenting, because your child’s digit ratios tell you what they’ll be like when they grow up!
I actually think the prenatal hormone material is compelling in a lot of ways, and I know some really great scholars in the area. I’m just not crazy about every article I’ve happened to read on it (of course, can’t we say that about all fields?). But who knows, maybe we’ll repeat some of these experiments soon and have it confirmed that men with higher androgen digit ratios are better at trading in the stock market.
Where I tend to get a touch queasy is under those occasional conditions where an author tries to take this proximate level analysis — an understanding of the impact of prenatal androgen exposure — and pull it up into the ultimate level — essential differences between women and men. When we get to that part of the semester, I have a link round-up that will put these other Around the Webs to shame.
The evolution of childhood
I only found one link on this, and it is a summary of some paleo evidence for when childhood may have evolved in our lineage. Fossil evidence was found of a 160,000 year old child with growth patterns that suggest it grew the way modern children grow.
Variation in childhood
First, a brief interview with Mel Konner about his recent book, The Evolution of Childhood (it sounds great! I would also recommend Meredith Small’s Our Babies, Ourselves). Then there’s also a nice post over at Neuroanthropology‘s old digs on a recent special issue of Anthropology News — they have direct pdf links to some very interesting articles. Finally, and this is related to something we only touched on in lecture but I’ll give us some time to discuss next week — check out this table of child well-being in rich countries (click on the table to embiggen, and the link under it for the full report). Might come as a surprise to see where the US ranks…
Your weekly dose of random
A lot of fun stuff this week for the college-aged. If you don’t read Female Science Professor, you should: she has an interesting blog post about the professor’s side of the story when a study says “I couldn’t come to class yesterday. Did I miss anything important?” See also this poem, and the post’s comments.
Also, if you’re a college student and don’t follow the Cronk of Higher Education, you’re missing some funny stuff. This week: Campus Reels as Freshman Discovers She is Not Best Friends With Roommate.
Next, a press release about an article showing better student performance with peer learning. This is why you all should be attending Undergraduate Mentor Office Hours!
Finally, what Around the Web post goes without linking to Ed Yong at least once? Here’s his take on research on strongly held beliefs: When in doubt shout — why shaking someone’s beliefs turns them into stronger advocates. As usual it’s an elegant and lively explanation of some very interesting research. And in the face of lots of pseudoscience, mistrust of science, and low science literacy, our understanding of how and why these things happen is very important.
