A new word has been added to the public’s vocabulary – the Zika virus. It seems we have one more infectious agent to worry about. Here are the facts as we currently understand them regarding the recent Zika epidemic, and also some rumors and conspiracy theories that need debunking.
The Zika virus (of the viral family Flaviviridae, an Arthropod-Borne or arbovirus) is spread through Aedes mosquito bites, the same mosquitoes that also spread dengue fever, West Nile, and yellow fever. The infections themselves are usually mild, causing fever, rash, joint pain, and conjunctivitis. Many of those infected (about 80%) may even have a subclinical infection, meaning they do not notice any symptoms.
According to the World Health Organization:
Zika virus is diagnosed through PCR (polymerase chain reaction) and virus isolation from blood samples. Diagnosis by serology can be difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.
A new study looking at the correlation of antidepressant use during pregnancy and the development of autism spectrum disorder (ASD) has been making headlines. While the results are likely significant, they are not as worrisome as the headlines may suggest.
The study: strengths and weaknesses
Overall the study design is solid. They followed 145,456 singleton full-term infants for a total of 904,035.50 person-years of follow-up. That is the strongest aspect of the study, its power. Typically when you capture large numbers you have to trade-off detail of information. As Lincoln might have said, you can capture a lot of information about a small number of people, or a small amount of information about a large number of people, but it is difficult to capture a lot of information about a large number of people.
The use of databases, especially in socialized countries, does help. In this case they used the ongoing population-based cohort, the Québec Pregnancy/Children Cohort. One compromise, however, is that they followed whether or not the mother filled a prescription for an anti-depressant. They did not capture whether or not the mother actually took the medication.
“Will Tylenol harm my baby?”
Pharmacists are among the most accessible of health professionals, and so we receive a lot of questions from the public. No appointment required, and the advice is free. Among the most frequent sources of questions are women seeking advice on drug use in pregnancy. This is an area where some health professionals are reluctant to tread. Some prefer to redirect all of these questions to physicians. But physicians are not always easily accessible, and few want to make an appointment just to ask what appears to be a simple question: Is it safe, or not? Admittedly, addressing questions about drug use in pregnancy can be challenging. There are no randomized controlled trials we can look to — there’s only messier, less definitive data. Our responses are filled with cautious hedging about risk and benefit, describing what we know (and don’t know) about fetal effects. In the pharmacy, one of the most common questions from pregnant women is about the use of acetaminophen (aka paracetamol aka APAP), more commonly known by the brand name Tylenol. Google “Tylenol and pregnancy” and you get 4.8 million results. Which source should you trust? (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…)
Could a vitamin with proven benefits in one group cause harm to another? That’s the growing concern with folic acid, the vitamin that dramatically reduces the risk of neural tube birth defects such a spina bifida. Studies designed to explore the possible benefits of folic acid for heart disease, stroke and cancer are giving out some worrying signs: At best, folic acid is ineffective, and at worst it may be increasing the risks of some cancers. So what does this say about routine supplementation for the typical healthy individual, and its overall risk and benefit?
Folate (vitamin B9) is an essential nutrient found green, leafy vegetables, broccoli, peas, corn, oranges, grains, cereals, and meats. Folate has important roles in the synthesis of DNA, and consequently cell division. Significant folate deficiency can lead to macrocytic anemia. Folic acid, a synthetic form of folate, is used in multivitamins supplements because it is better absorbed.
Folic acid’s benefits in pregnancy are well documented. Supplementation before conception, and in the first few weeks of pregnancy, significantly and substantially lower the risk of several different birth defects, including neural tube defects (NTDs). The neural tube is the embryonic precursor to the brain and spinal column. NTDs include very serious defects like spinal bifida and anencephaly, birth without part of the brain.
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…)
I read this Reuters Health article on MedlinePlus, and then I read the study the article referred to (The impact of acupuncture on in vitro fertilization) and now my head hurts. The study found that acupuncture was not effective in increasing the pregnancy rate (PR) during in vitro fertilization (IVF). As quoted on MedlinePlus, the lead author, Alice Domar, seems to blame her patients (the presumably poor quality of their embryos) rather than acupuncture for the lack of success, and then she recommends using acupuncture even if it doesn’t work. That was bad enough, but “poor quality embryos” is a hypothesis that was actually tested and rejected in the study itself. Has Domar forgotten?
The headline of the MedlinePlus article says “acupuncture doesn’t boost IVF success for all” – suggesting that it boosts success for some? Then the first sentence says the study suggested that acupuncture doesn’t work, period. But wait…
The lead researcher says acupuncture may not have worked in her study because, unlike past research, her investigation wasn’t limited to women who had good quality embryos available for transfer. “I’m wondering if my sample was just not a good sample, in that most of the patients in my study were probably not the best-prognosis patients,”
Domar and her team say the most likely explanation for the lack of an acupuncture effect in their study was the fact that they included many women who didn’t have good quality embryos available for transfer. While acupuncture may help a woman become pregnant after the transfer of a healthy embryo, the researcher noted in an interview, it can’t repair an embryo with chromosomal defects or other abnormalities.
Hold the boat!! In the Discussion section of the paper itself, Domar et al point out that previous research has included mostly patients with good quality embryos. They ask if perhaps acupuncture only works for good quality embryos? They test that hypothesis by separately analyzing the subjects in this study who had good quality embryos. There was no increase in PR with acupuncture in this sub-group; the results were the same as for the entire sample. (more…)