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…
Abortion did not cause this.
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.
Between 3-4% of babies begin labor in the breech (bottom first) position, increasing the risk of neonatal morbidity and mortality. Pre-emptive C-section has become the preferred method of delivery for breech babies, but now some are questioning this recommendation. The controversy is fueled by differing appraisals of the danger and by differing assessments of the whether any risk of neonatal death can be justified in the age of the safe Cesarean.
The best conducted and most important study comparing breech vaginal delivery with elective C-section is the Term Breech Trial (TBT) conducted by Mary Hannah and colleagues. It is the only randomized control trial of its kind.
… [W]e found that the fetuses of women allocated planned caesarean section were significantly less likely to die or to experience poor outcomes in the immediate neonatal period than the fetuses of women allocated planned vaginal birth. Although some of the deaths in the planned vaginal birth group were related to difficulty with vaginal breech delivery, others were clearly associated with problems during labour. Thus the avoidance of labour and vaginal breech delivery could have contributed to better outcomes with planned caesarean section…
A more recent trial, the PREMODA (PREsentation et MODe d’Accouchement: presentation and mode of delivery) study produced different findings and as a result, some obstetricians have been calling for a re-evaluation of the standard recommendation for C-section delivery of a breech baby. (more…)
As a mother, I am a passionate advocate of breastfeeding and I breastfed my four children. As a clinician, though, I need to be mindful not to counsel patients based on my personal preferences, but rather based on the scientific evidence. While breastfeeding has indisputable advantages, the medical advantages are quite small. Many current efforts to promote breastfeeding, while well meaning, overstate the benefits of breastfeeding and distorts the risks of not breastfeeding, particularly in regard to longterm benefits.
As Joan Wolf explains in an article entitled Is Breast Really Best? Risk and Total Motherhood in the National Breastfeeding Awareness Campaign:
… Medical journals are replete with contradictory conclusions about the impact of breast-feeding: for every study linking it to better health, another finds it to be irrelevant, weakly significant, or inextricably tied to other unmeasured or unmeasurable factors. While many of these investigations describe a correlation between breast-feeding and more desirable outcomes, the notion that breast-feeding itself contributes to better health is far less certain, and this is a crucial distinction that breast-feeding proponents have consistently elided. If current research is a weak justification for public health recommendations, it is all the more so for a risk-based message that generates and then profits from the anxieties of soon-to-be and new mothers…
Wolf describes the problems with many studies of breastfeeding, particularly those that focus on long term outcomes:
In breast-feeding studies, potential confounding makes it difficult to isolate the protective powers of breast milk itself or to rule out the possibility that something associated with breast-feeding is responsible for the benefits attributed to breast milk. As the number of years between breastfeeding and the measured health outcome grows, so too does the list of possibly influential factors, which means that the challenge is magnifiedwhen trying to evaluate long-term benefits of breastfeeding… Breast-feeding, in other words, cannot be distinguished from the decision to breast-feed, which, irrespective of socioeconomic status or education,could represent an orientation toward parenting that is itself likely to have a positive impact on children’s health. In instances such as this, in which the exposure (breast-feeding) and confounder (behavior) are likely to be very highly correlated, confounding is especially difficult to detect. When behavior associated with breast-feeding has the potential to explain much of the statistical advantage attributed to breast milk, the scientific claim that breast-feeding confers health benefits … needs to be reexamined.
The new mantra of midwives and their advocates is “evidence based practice.” Lamaze, the childbirth education organization has changed the name of their blog to “Science and Sensibility” emphasizing the importance of science and promising:
Lamaze education and practices are based on the best, most current medical evidence available, and can help reduce the overuse of unnecessary interventions while improving overall outcomes for mothers and babies.
But midwives and childbirth educators like Lamaze have a problem. The scientific evidence often conflicts with their ideology. They could address this problem in several ways. Midwives could modify their specific ideological beliefs on the basis of scientific evidence. Childbirth educators could question whether ideology has had an inappropriate impact on the promulgation and validation of their recommendations. Both those approaches would involve a threat to cherished beliefs. They, therefore, have taken a different approach. They’ve tried to justify ignoring scientific evidence.
As midwives Jane Munro and Helen Spiby have documented in The Nature and Use of Evidence in Midwifery, the first chapter of their book Evidenced Based Midwifery, midwives were initially enthusiastic about basing clinical practice on scientific evidence. That’s because they had long told each other that midwifery was “science based” while obstetrics was not:
At the beginning of the evidence based practice movement, much of the midwifery profession responded enthusiastically to the potential for change… Evidence based practice was seen to be offering a powerful tool to question and examine obstetric-led models of care that had dominated the previous decades. The results of such examination could have meant ‘starting stopping’ the unhelpful interventions that had embedded themselves in common practice …
Its authors boast that it is one of the ten most downloaded papers from the British Medical Journal (BMJ). That makes it even more unfortunate that the conclusions of the paper are directly at odds with the findings of the paper. Outcomes of planned home births with certified professional midwives: large prospective study in North America by Kenneth Johnson and Bettye Ann Davis is the premier paper on the safety of American homebirth. It claims to show that homebirth is as safe as hospital birth, but actually shows that homebirth has nearly triple the neonatal death rate of hospital birth for comparable risk women.
Johnson and Daviss, in collaboration with the Midwives Alliance of North America (MANA), the organization of American homebirth midwives, collected data on all homebirths attended by Certified Professional Midwives (CPMs, homebirth midwives, as distinct from CNMs, Certified Nurse Midwives) in the year 2000. Then the authors compared the outcomes for interventions and for neonatal deaths with a hospital group.
According to Johnson and Davis, when analyzing the different intervention rates of home and hospital:
We compared medical intervention rates for the planned home births with data from birth certificates for all 3 360 868 singleton, vertex births at 37 weeks or more gestation in the United States in 2000, as reported by the National Center for Health Statistics [Births: final data for 2000. National vital statistics reports. Martin JA, Hamilton BE, Ventura SJ, Menacker F, Park MM. Hyattsville, MD: National Center for Health Statistics, 2002;50(5)]
They used singleton, vertex births at 37+ weeks as a proxy for low risk women. They found, not surprisingly, that intervention rates are lower for homebirth. Then they turned to neonatal mortality rates. They should have compared the neonatal mortality rate of the homebirth group to the neonatal mortality rate of the hospital birth group, but they did not. Instead, they compared homebirth deaths to hospital births in a variety of out of date studies extending back more than 20 years.
The authors conclude:
Waterbirth has been touted as an alternative form of pain relief in childbirth. Indeed, it is often recommended as the method of choice for pain relief in “natural” childbirth. It’s hardly natural, though. In fact, it is completely unnatural. No primates give birth in water, because primates initiate breathing almost immediately after birth and the entire notion of waterbirth was made up only 200 years ago. Not surprisingly, waterbirth appears to increase the risk of neonatal death.
Perinatal mortality and morbidity among babies delivered in water: surveillance study and postal survey was published in the BMJ in 1999. Out of 4,030 deliveries in water, 35 babies suffered serious problems and 3 subsequently died. It is unclear if any of the deaths can be attributed to delivery in water. However, of the 32 survivors who were admitted to the NICU, 13 had significant respiratory problems including pneumonia, meconium aspiration, water aspiration, and drowning. Other complications attributable to water birth include 5 babies who had significant hemorrhage due to snapped umbilical cord. In all, 18 babies had serious complications directly attributable to waterbirth. The risk of serious complications necessitating prolonged NICU admissions was 4.5/1000.
Hospitals in Ireland suspended the practice of waterbirth after a baby died from freshwater drowning after delivery in a waterbirth pool.
The most nonsensical aspect of waterbirth is that it puts the baby at risk for freshwater drowning. The second nonsensical aspect is that the baby is born into what is essentially toilet water, because the water in the pool is fecally contaminated. In Water birth and the risk of infection; Experience after 1500 water births, Thoeni et al. analyzed the water found in waterbirth pools both before and after birth. The water in a birth pool, conveniently heated to body temperature, the optimum temperature for bacterial growth, is a microbial paradise.
Who said: “the mother is the factory, and by education and care she can be made more efficient in the art of motherhood”?
That was written in 1942 by Grantly Dick-Read, widely considered to be the father of modern natural childbirth. Most people don’t realize that natural childbirth was invented by a man to convince middle and upper class women that childbirth pain is in their minds, thereby encouraging them to have more children. Read’s central claim was that “primitive” women do not have pain in childbirth. In contrast, women of the upper classes were “overcivilized” and had been socialized to believe that childbirth is painful.
In Holistic obstetrics: the origins of “natural childbirth” in Britain, O Moscucci, PMJ 2003;79:168-173, Dr. Ornella Moscucci explains the backdrop against which the philosophy of “natural” childbirth was promulgated:
Health policy became the subject of intense public debate in the aftermath of the Boer war, when Britain’s near defeat at the hands of a barely trained army focused the attention on the physical fitness of new recruits… Adherents to the new science of eugenics on the other hand blamed heredity. In their view, health policy should aim to prevent reproduction among “low quality” human stock .., and encourage reproduction among “good” stock…
The development of “natural childbirth” owed much to the activities of physicians and health professionals who were in sympathy with the aims of reform eugenics…
[T]hese health reformers were concerned about the differential birth rate—the tendency of poorer, less healthy sections of society to have larger families than their “betters”. Thus, as well as endorsing plans for the sterilisation and detention of “degenerates”, they also sought to encourage the middle classes to have more children… Female education and employment were seen as a particular evil, insofar as they led women to regard motherhood a burden and to neglect hearth and home…
One obvious way to reverse the falling birth was to entice women of “superior stock” back into the home, where they would fulfill their functions as wives and mothers. Health reformers took up the challenge by developing an ideology of childbirth that emphasised the “naturalness” of pregnancy and birth. This ideology functioned at a number of levels. It was prescriptive, in that it rooted woman’s social role in her biological capacity for reproduction… Motherhood was not only a woman’s supreme fulfilment and reward, but also her civic duty…
Read himself stated:
“Woman fails when she ceases to desire the children for which she was primarily made. Her true emancipation lies in freedom to fulfil her biological purposes”..
Editor’s Note: Dr. Mark Crislip has been kidnapped by anti-vaccinationists. Fortunately, we have sent our black Illuminati, pharma-funded, vaccine-wielding helicopters to rescue him, but unfortunately, as a result of his trauma, his usual Friday post is likely to be delayed either until this afternoon or Saturday. In any case, fortunately for us our latest addition to the SBM crew, Dr. Tuteur, was willing to fill in on short notice; so here she is. Dr. Crislip will post by tomorrow. To whet your appetite for his patented sarcasm, let me just say that he will be having a little fun with a certain article from The Atlantic about flu vaccines. There, now doesn’t that make you want to check back tomorrow to find out what his take is on the article? I thought it would.
Buried in the midst of it new report, Monitoring emergency obstetric care; a handbook, the World Health Organization acknowledges what obstetricians have been saying for some time. The WHO’s goal of a 10-15% C-section rate lacks any empirical basis.
Earlier editions of this handbook set a minimum (5%) and a maximum (15%) acceptable level for caesarean section. Although WHO has recommended since 1985 that the rate not exceed 10–15%, there is no empirical evidence for an optimum percentage or range of percentages …
Of course, they’re not going to give up their recommendation simply because there is no science that supports it, insisting that “a growing body of research that shows a negative effect of high rates.”
Dr. Marsden Wagner, former head of the Perinatal Division of the WHO, appears to be responsible for the purported optimal C-section rate of 10-15%, the level at which both maternal and neonatal mortality rates are supposedly the lowest. Ironically, Dr. Wagner is a co-author of a recent study that actually demonstrates the opposite.