When women live together, do their menstrual cycles tend to synchronize? It’s been a long time since I first heard that claim. I didn’t believe it, for a number of reasons. I had never observed it myself, I saw no plausible mechanism to explain how it could happen, I thought the statistics to prove it would be problematic and complicated, and I suspected that confirmation bias and selective memory might have persuaded people that a spurious correlation existed. How often do women say “Oh, look! We’re having our periods at the same time”? How often do they say “Oh, look! We’re having our periods at different times”? Now that many years have passed since my first encounter, I thought it would be fun to revisit the claim and see whether science has supported it or rejected it.
A perusal of PubMed and other Internet sources left me confused and amused. (more…)
Several questionable sources are spreading alarms about the possible dangers of prenatal ultrasound exams (sonograms). An example is Christine Anderson’s article on the ExpertClick website. In the heading, it says she “Never Liked Ultrasound Technology.”
[She] has never been sold on the safety using Ultrasounds for checking on the fetuses of pregnant women, and for the last decade her fears have been confirmed with a series of studies pointing to possible brain damage to the babies from this technology.
Should We Believe Her?
Should we avoid ultrasounds because Anderson never liked them? Should we trust her judgment that her fears have been confirmed by studies? Who is she?
“Dr.” Christine Anderson is a pediatric chiropractor in Hollywood who believes a lot of things that are not supported by science or reason. Her website mission statement includes
We acknowledge the devastating effects of the vertebral subluxation on human health and therefore recognize that the spines of all children need to be checked soon after birth, so they may grow up healthy.
It also states that “drugs interfere… and weaken the mind, body, and spirit.” Anderson is a homeopath, a craniosacral practitioner, a vegan, and a yoga teacher. She advises her pregnant patients to avoid toxins by only drinking filtered water and only eating organic foods. She sells her own yoga DVD. (more…)
A correspondent asked me to review the book What to Expect When You’re Expecting by Heidi Murkoff and Sharon Mazel. She wrote “I’m very worried about this book.”
She had just seen an NPR article about the book and was alarmed because it provided an excerpt from the book recommending that patients with morning sickness “Try Sea-Bands” and “Go CAM Crazy.” She knew from reading SBM and other science blogs that “going CAM crazy” is not a good idea. She was savvy enough to search Google Books with the title and “CAM” and found more alarming advice. (more…)
After giving birth, most mammals eat the afterbirth, the placenta. Most humans don’t. Several hypotheses have been suggested as to why placentophagy might have had evolutionary survival value, but are there any actual benefits for modern women? Placentophagy has been recommended for various reasons, from nutritional benefit to preventing postpartum depression to “honoring the placenta.” In other cultures, various rituals surround the placenta including burial and treating it as sacred or as another child with its own spirit. Eating the placenta is promoted by some modern New Age, holistic, and “natural-is-good” cultural beliefs.
Some women eat it raw, but many women have a yuck-factor objection to eating raw bloody tissue. It can be cooked: recipes are available for preparing it in various ways. For those who don’t like the idea of eating the tissue, placenta encapsulation services are available, putting placenta into a capsule that is more esthetically acceptable and that can even be frozen and saved for later use in menopause.
Does placentophagia benefit health? Does it constitute cannibalism? It it just a way to recycle nutrients? How can science inform our thinking about this practice? (more…)
A new article in the Journal of Women’s Health by Westhoff, Jones, and Guiahi asks “Do New Guidelines and Technology Make the Routine Pelvic Examination Obsolete?”
The pelvic exam consists of two main components: the insertion of a speculum to visualize the cervix and the bimanual exam where the practitioner inserts two fingers into the vagina and puts the other hand on the abdomen to palpate the uterus and ovaries. The rationales for a pelvic exam in asymptomatic women boil down to these:
- Screening for Chlamydia and gonorrhea
- Evaluation before prescribing hormonal contraceptives
- Screening for cervical cancer
- Early detection of ovarian cancer
None of these are supported by the evidence. Eliminating bimanual exams and limiting speculum exams in asymptomatic patients would reduce costs without reducing health benefits, allowing for better use of resources for services of proven benefit. Pelvic exams are necessary only for symptomatic patients and for follow-up of known abnormalities. (more…)
Is unmedicated natural childbirth a good idea? The American College of Obstetrics and Gynecology (ACOG) points out that
There is no other circumstance in which it is considered acceptable for a person to experience untreated severe pain, amenable to safe intervention, while under a physician’s care.
It is curious when an effective science-based treatment is rejected. Vaccine rejecters have been extensively discussed on this blog, but I am intrigued by another category of rejecters: those who reject pain relief in childbirth. They seem to fall into 3 general categories:
- Religious beliefs
- Objections based on safety
1. “In pain you will bring forth children” may be a mistranslation, and it certainly is not a justification for rejecting pain relief. Nothing in the Bible or any other religious text says “Thou shalt not accept medical interventions to relieve pain.” Even the Christian Science church takes no official stand on childbirth and its members are free to accept medical intervention if they choose.
2. The natural childbirth movement seems to view childbirth as an extreme sport or a rite of passage that is empowering and somehow enhances women’s worth. Women who “fail” and require pain relief or C-section are often looked down upon and made to feel guilty or at least somehow less worthy.
3. I’m not impressed by religious or heroic arguments, although I support the right of women to reject pain relief on the autonomy principle. What inquiring science-based minds want to know is what the evidence shows. Does avoiding medical treatment for pain produce better outcomes for mother and/or baby? It seems increasingly clear that it doesn’t. A new book, Epidural Without Guilt: Childbirth Without Pain, by Gilbert J. Grant, MD, helps clarify these issues.
More and more American women (1 in 200) are opting for home birth, and midwife-assisted home birth is common in other developed countries. How safe is it compared to birth in a hospital? A new study sheds some light on the subject. It was recently published in the American Journal of Obstetrics and Gynecology: Maternal and newborn outcomes in planned home birth vs planned hospital births: a metaanalysis, by Wax et al.
All the existing studies have flaws. It would be ideal to do a study where women were randomly assigned to home or hospital birth; that isn’t possible, so we have to fall back on studies that are possible. Just comparing home births to hospital births isn’t good enough, because high-risk births occur primarily in hospitals, and between 9% and 37% of planned home births end up with transfer to the hospital during labor and are converted into hospital births. Cohort studies comparing planned home with planned hospital births provide the best sources of data by intended delivery location. There have been several such studies, but the numbers were small and the results were inconclusive. This new study is a meta-analysis that combines the data into one large set for better understanding. (more…)
We know that drinking alcohol during pregnancy can cause birth defects; the government-mandated warnings on alcoholic beverage labels constantly remind us of that fact. But toxicologists remind us that the poison is in the dose: what is the dose of alcohol that causes birth defects? Heavy drinking can cause fetal alcohol syndrome, but there is no evidence that light to moderate drinking can cause it. Alcohol has been implicated in a number of other adverse effects on pregnancy and on the fetus. We simply don’t know if there is a threshold dose below which alcohol intake is safe, so the default position of most medical authorities has been to advise total abstinence during pregnancy. This is not a truly evidence-based recommendation, but rather an invocation of the precautionary principle. Those advising complete abstinence have been accused of paternalism and bias by wine-lovers and other critics, for instance here and here.
The literature on alcohol and pregnancy is extensive and confusing. It addresses many different endpoints, looking at effects on children and on the pregnancy itself. The studies are inconsistent in how they define “moderate” or “light” drinking, and they rely on self-reports that may not be accurate.
It would be impossible to read and accurately summarize such a large body of literature (over 21,000 hits on PubMed!), but here are a few examples that illustrate the scope, diversity, and conflicting results of these studies: (more…)
One of the basic principles of science-based medicine is that a single study rarely tells us much about any complex topic. Reliable conclusions are derived from an assessment of basic science (i.e prior probability or plausibility) and a pattern of effects across multiple clinical trials. However the mainstream media generally report each study as if it is a breakthrough or the definitive answer to the question at hand. If the many e-mails I receive asking me about such studies are representative, the general public takes a similar approach, perhaps due in part to the media coverage.
I generally do not plan to report on each study that comes out as that would be an endless and ultimately pointless exercise. But occasionally focusing on a specific study is educational, especially if that study is garnering a significant amount of media attention. And so I turn my attention this week to a recent study looking at acupuncture in major depression during pregnancy. The study concludes:
The short acupuncture protocol demonstrated symptom reduction and a response rate comparable to those observed in standard depression treatments of similar length and could be a viable treatment option for depression during pregnancy.
Editor’s note: Given the controversial nature of the topic, I think it’s a good time to point out my disclaimer before this post. Not that it’ll prevent any heated arguments or anything…
The Science-Based Medicine blog was started slightly over two years ago, and this is a post I’ve wanted to do since the very beginning. However, since January 2008, each and every time I approached this topic I chickened out. After all, the topic of abortion is such a hot button issue that I seriously questioned whether the grief it would be likely to cause is worth it. (Take the heat generated any time circumcision is discussed here and ramp it up by a factor of 10.) On the other hand, there is so much misinformation out there claiming a link between abortion and the subsequent development of breast cancer when the data simply don’t support such a link, and the name of this blog is Science-Based Medicine. Why should I continue to shy away from a topic just because it’s so religiously charged? More importantly, in my discussion how can I focus attention on the science rather than letting the discussion degenerate into the typical flamefest that any discussion of abortion on the Internet (or anywhere else, for that matter) will almost inevitably degenerate into. Indeed, such discussions have a depressing near-inevitability of validating Godwin’s law not once but many times — usually within mere hours, if not minutes.
My strategy to try to keep the discussion focused on the science will be to stay silent about my own personal opinions regarding abortion and, other than using it to introduce my trepidation about discussing the topic, the religious and moral arguments that fuel the controversy. That’s because the question of whether abortion is the murder of a human being, merely the removal of a lump of tissue, or somewhere in between is a moral issue that, at least as far as I’m concerned, can’t ever be definitively answered by science. That is why it is not my purpose to sway readers towards any specific opinion regarding the morality of abortion. Indeed, I highly doubt that any of our readers care much about my opinions on the matter. On the other hand, I would hope that I’ve built up enough trust over the last two years that our readers will be interested in my analysis of the existing data regarding something another related issue. It is my purpose to try to dispel a myth that is not supported by science, specifically the claim that elective abortion is causes breast cancer or is a very strong risk factor for its subsequent development. That is a claim that can be answered by science and, for the most part, has been answered by science with a fairly high degree of certainty. Despite the science against it, the medical myth that abortion causes breast cancer or vastly increases the risk of it is, like the myth that vaccines cause autism, a manufactroversy that won’t die, mainly because it is largely fueled by religious beliefs that are every bit as immune to science as the ideological beliefs that drive the antivaccine movement.