High Doses of Caffeine Found to Increase Risk of Miscarriage

perineal trauma, was not assessed. The amount of time warm packs were applied was not recorded. The influence of episiotomy on perineal pain is unclear. Though both groups had the same rate of episiotomy, it did not appear as a confounding variable. Does the definition of perineal trauma, as used in this study, include or exclude women with episiotomy? This is not explained. There are implications for midwives in this study. Most importantly, this paper represents one of the first randomized controlled trials of a simple, inexpensive, readily available (in most settings) analgesic measure shown to decrease perineal pain during birth and in the early postpartum period, and to reduce reports of urinary incontinence at 3 months postpartum. Though the mechanisms by which these effects occur are mostly speculative, the benefits of using a perineal compress during the second stage of labor outweigh any risks, and this practice can be readily incorporated into the care of laboring women. Further study using a similarly rigorous design with active, ongoing appraisal of procedures and greater adherence to issues of fidelity will likely shed more light on the benefits of warm compresses and their mechanisms of action. HIGH DOSES OF CAFFEINE FOUND TO INCREASE RISK OF MISCARRIAGE Weng X, Odouli R, Li DK. Maternal caffeine consumption during pregnancy and the risk of miscarriage: A prospective cohort study. Am J Obstet Gynecol 2008 Epub ahead of print. Available from: www.ajog.org/webfiles/images/journals/ymob/mob999082637p.pdf [Accessed January 29, 2008]. Reviewed by: Sharon Bond, CNM, APRN-BC. The use of caffeine-containing beverages during pregnancy has been controversial; many sources state that small amounts of caffeine during pregnancy cause no harm. However, earlier studies may be flawed because of design problems, small sample sizes, and the role of confounding factors, such as early pregnancy symptoms, that were not always taken into account. The intent of this study is to investigate whether caffeine consumption is associated with spontaneous abortion (SAB) when controlling for other symptoms related to early pregnancy, such as nausea and vomiting. Members of Kaiser Permanente’s health program who were newly diagnosed with pregnancy and who spoke English were invited to enroll. Of the 2729 women determined to be eligible, 1063 completed the study, which consisted of an in-person interview conducted shortly after the diagnosis of pregnancy. The median gestational age was 40 days at the time of enrollment and 10 weeks at the time of the interview. Interviewers asked detailed questions concerning types, timing, and the amount of caffeinecontaining beverages, as well as changes in caffeine intake since learning of pregnancy. Researchers calculated converJournal of Midwifery & Women’s Health • www.jmwh.org

sion factors to determine the amounts of caffeine intake. For example, “for each 150 milliliters of a beverage, 100 milligrams (mg) of caffeine was assigned to caffeinated coffee, 2 mg to decaffeinated coffee, 39 mg for caffeinated tea, 15 mg for caffeinated soda, and 2 mg for hot chocolate.” Demographic and previous and current pregnancy information was collected. Participants were followed to miscarriage, pregnancy termination, or other factors, such as ectopic, or up to 20 weeks’ completed gestation. Measurement of caffeine was categorized as 0 mg/day for nonusers, less than 200 mg/day and 200 mg or greater/day. A Cox proportional hazards regression model, a powerful statistical test to analyze data when timing to an event (miscarriage) is important, rather than the fact it occurs, is used to analyze data. This test also assists researchers to consider a relationship between an event and an exposure while controlling for other factors. The rate of SAB among women in the study was 16.8%. Rates of SAB among all pregnancies in the United States range between 10% to 30%. Most of these occur before 8 weeks’ gestation, and rates increase from 10% among women in their twenties to 90% among women at age 45 and above.1 In this study, the findings show a significant increase in rates of SAB both before and after 8 weeks’ gestation among women with higher caffeine consumption (⬎200 mg/day), regardless of the source of caffeine. However, the risk of SAB among women using less than 200 mg/day and 0 mg/day was very similar. Authors controlled for a number of variables, including maternal age, history of previous miscarriage, race, symptoms such as nausea/ vomiting, exposure to magnetic fields, smoking, alcohol, drug use, and the use of Jacuzzi pools. The effects of caffeine appeared to be greater among nonsmokers, women without a history of previous SAB, and those with symptoms of nausea/vomiting. As possible explanations, the authors speculate that caffeine consumption may be less of a risk factor for SAB when other risk factors (such as repeated SABs) are also present. This study has several strengths that make it important for midwives. The cohort design is rigorous, and the statistical analysis is an appropriate method for the research question. Participants were typically interviewed within a month of learning about their pregnancies, thus minimizing recall bias. The authors further sought to minimize this influence by analyzing results collected before or after SAB, and no differences were evident. The sample size is large, though no power analysis is included. Records were centralized and readily accessible because of women’s participation in Kaiser Permanente’s health system. One shortcoming is the difficulty with determining the exact amounts of caffeine in beverages. In this study, coffee was the beverage most often cited as the source of caffeine. The precise amount of caffeine in a drink differs according to brand, brewing method, and the volume that constitutes “a cup.” Therefore, conversion methods used in other studies were applied here. 273

Reports of this paper made national news. Consequently, our clients are likely to inquire about its significance. This study may represent new information for many midwives. If an 8-ounce cup of caffeinated coffee contains about 240 mg of caffeine, this can be compared with our client’s recall of daily intake. When doing preconception counseling, midwives now have strong evidence to recommend avoidance of caffeine not only early in pregnancy, but during periods of prepregnancy planning as well. Consider including this recommendation along with other health guidance advice given to woman during their routine or annual visits. REFERENCE 1. Heffner LJ. Advanced maternal age— how old is too old? N Engl J Med 2004;351:1927–9.

ACADEMIC AFFILIATION MAY COUNT FOR ACCURACY WHEN RADIOLOGISTS INTERPRET MAMMOGRAMS, BUT NO SINGLE CHARACTERISTIC EXPLAINS THE VARIATION IN INTERPRETING RESULTS Miglioretti DL, Smith-Bindman R, Abraham L, Brenner J, Carney PA, Aiello Bowles EJ, et al. Radiologist characteristics associated with interpretive performance of diagnostic mammography. J Natl Cancer Inst 2007;99:1854 – 63. Reviewed by: Sharon Bond, CNM, APRN-BC. Previous studies examining the sensitivity of mammography have focused on variation in the interpretation of results among screening mammography, based primarily on characteristics of the patient or the imaging technology. These earlier studies found that positive predictive values ranged from 6% to 92% among radiologists who recommended biopsy. In this study, authors examine differences in sensitivity and false-positive rates for 123 radiologists’ interpretations of 35,895 diagnostic mammograms where the likelihood of finding true breast cancer is 10 times higher than among women receiving screening mammography. In this particular study, researchers focused their lens on the radiologists rather than equipment or patient characteristics and wondered whether differences in performance were attributable to characteristics of the radiologists. This study took place within three major mammography registries (72 facilities) affiliated with the National Cancer Institute–funded Breast Cancer Surveillance Consortium between 1996 and 2003. Radiologists were invited to participate via a mailed survey in 2002. Individuals who did not meet volume requirements for the Mammography Quality Standards Act of 1992 were excluded. The survey inquired about demographics, training in radiology, total number and amount of time spent reviewing diagnostic vs. screening mammograms, type of clinical practice, and numbers of biopsies performed. Survey data were linked to interpretive performance retrieved from the cancer registries of the respective institutions. For this study, sensitivity (the ability of a test to correctly 274

determine who has disease) was defined as the percentage of positive examinations found within 1 year of the diagnostic mammogram. A false-positive rate was defined as the percentage of positive diagnostic mammograms in women not shown to have disease. Performance of radiologists was examined by use of multivariable models adjusted for patient age, breast density, time since last mammogram, self-reported presence of a breast lump, and registry. During the study, 40 out of every 1000 mammograms (N ⫽ 35,895) were found to have breast cancer. The median sensitivity for detecting cancer was 79%, while the falsepositive rate was 4.3%. Most radiologists were male and had been interpreting mammography for at least 10 years, spending less than 40% of their time working in breast imaging. Ninety-three percent reported that more than half of the mammograms they interpreted were screening rather than diagnostic, the subject of this study. Six percent had academic medical center appointments, and those with fellowship training in breast imaging represented only 3% of radiologists participating and had less than 10 years of experience. Fellowship training in breast imaging is a new specialty; hence these individuals are relative newcomers to the field, have fewer years of experience, and represent only a few of the radiologists in this study. Authors point out determining differences in performance interpretation is not as straightforward as it might seem. For example, sensitivity and specificity are inversely related, and institutions (or individual radiologists) have differing thresholds. There is no “best” answer here, because improving detection of cancer (sensitivity) will result in greater numbers of false-positive mammograms with inherent costs of follow-up testing and fear. The authors conclude by suggesting that differences in both threshold and accuracy are important. In general, they find that radiologists perform with higher sensitivity and lower false-positive rates when affiliated with academic medical centers. However, because only 7 of 123 radiologists studied have academic affiliations and interpret only 6.5% of all mammograms in the United States, this finding may not be generalizable. The authors recommend finding ways in which accuracy of interpretation could be improved while variation in interpretation is reduced. The effects of educational interventions, double readings, audits, and direct feedback were a few of the measures recommended by the authors in need of further study. ANTHROPOLOGY TEAM AT HARVARD UNCOVERS EVOLUTIONARY EVIDENCE OF LORDOSIS TO SUPPORT DISTRIBUTION OF PREGNANCY WEIGHT Whitcome KK, Shapiro LJ, Lieberman DE. Fetal load and the evolution of lumbar lordosis in bipedal hominins. Nature 2007; 450:1075– 8. Reviewed by: Sharon Bond, CNM, APRN-BC. Volume 53, No. 3, May/June 2008