- Email: [email protected]
April 2008
EVIDENCE-BASED PRACTICE
R. Rima Jolivet, CNM, MSN, MPH
Current Resources for Evidence-Based Practice, March/April 2008 Published simultaneously in Journal of Obstetric, Gynecologic & Neonatal Nursing 2008;37(2).
THE “DISCIPLINED SUBJECTIVITY” OF META-ANALYSIS A critique of the 2005 Cochrane review of randomized controlled trials comparing home-like versus hospital settings for birth1 has focused debate on methodologic challenges of meta-analysis. Criticism centered on criteria used to assess studies for inclusion and quality of the underlying studies, particularly whether they defined and controlled the treatment in each arm sufficiently to ensure trials offered valid comparisons between two discrete conditions.2 Meta-analyses can increase the statistical power and precision of estimates of effect by pooling data from studies that explore the same research question using comparable parameters. It is useful for clarifying results of multiple, similar small or conflicting studies. Pooling data does not, however, correct problems of quality in the contributing studies; it merely concentrates their unreliable conclusions. Judging which studies may be included in a metaanalysis is complicated and entails many decisions. Some focus on the quality of trials; others consider study design and format of the data. These decisions are made to satisfy the statistical assumptions of meta-analysis; nonetheless, they involve subjective judgments, may impact review conclusions, and are often not described explicitly. Voils et al.3 detail the methodologic considerations they faced when deciding which trials to include in a planned meta-analysis. To illustrate the “disciplined subjectivity” of meta-analysis and its impact on the resulting review, they describe the process of culling data from 29 trials for pooled analysis. After ensuring the statistical compatibility of study designs, methods to control or adjust for confounding, operationalization of variables, and metrics used to express the data, the authors report they had to exclude 73% to 87% of all observations, leaving very little of the original data to synthesize. In response to the critique of their Cochrane review on birth setting, Hodnett and Downe4 quote the Cochrane Handbook, noting that “much more research is needed to determine which criteria for validity assessment are important influences on study results.” Journal of Midwifery & Women’s Health • www.jmwh.org
1. Hodnett ED, Downe S, Edwards N, Walsh D. Home-like versus conventional institutional settings for birth. Cochrane Database Syst Rev 2005;1:CD000012. 2. Fahy K, Tracy SK. Critique of Cochrane systematic review of home-like setting for birth, Int J Evid Based Healthc 2007;5:360 – 4; Rejoinder, 367. 3. Voils CI, Barroso J, Haselblad V Sandelowski M. In or out? Methodological considerations for including and excluding findings from a meta-analysis of predictors of antiretroviral adherence in HIV-positive women. J Adv Nurs 2007;59:163–77. 4. Hodnett ED, Downe S. Response to critique of Cochrane systematic review of home-like setting for birth in the International Journal of Evidence-Based Healthcare. Int J Evid 2007;5:365– 6. FROM COCHRANE DATABASE OF SYSTEMATIC REVIEWS (CDSR), ISSUE 4, 2007 New Systematic Reviews ● ● ● ●
● ● ● ● ● ●
Amniotomy for shortening spontaneous labour Chinese herbal medicine for primary dysmenorrhoea Exercise for vasomotor menopausal symptoms Fundal pressure versus controlled cord traction as part of the active management of the third stage of labour Local cooling for relieving pain from perineal trauma sustained during childbirth Nutrient-enriched formula versus human breast milk for preterm infants following hospital discharge Phytoestrogens for vasomotor menopausal symptoms Prebiotics in infants for prevention of allergic disease and food hypersensitivity Probiotics in infants for prevention of allergic disease and food hypersensitivity Psychosocial and psychological interventions for treating postpartum depression
Updated Systematic Reviews ● ● ● ● ●
Antibiotics for incomplete abortion Continuous versus interrupted sutures for repair of episiotomy or second degree tears Copper containing, framed intra-uterine devices for contraception Danazol for pelvic pain associated with endometriosis Enemas during labour 163 1526-9523/08/$34.00 • doi:10.1016/j.jmwh.2007.12.013
Issued by Elsevier Inc.
● ● ● ● ●
Formula milk versus maternal breast milk for feeding preterm or low birth weight infants Hands and knees posture in late pregnancy or labour for fetal malposition (lateral or posterior) Nonsteroidal anti-inflammatory drugs for heavy menstrual bleeding Progestogens versus oestrogens and progestogens for irregular uterine bleeding associated with anovulation Venepuncture versus heel lance for blood sampling in term neonates
Cochrane reviews are available by subscription to The Cochrane Library, and review abstracts are available without charge. See www.thecochranelibrary.com FROM DATABASE OF ABSTRACTS OF REVIEWS OF EFFECTS (DARE) Recent Abstract Entries Assessing Quality of Systematic Reviews ● ●
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● ●
●
An integrated review of the literature on demand feedings for preterm infants Improved effectiveness of partner notification for patients with sexually transmitted infections: systematic review Interventions to improve interactions between drug abusing mothers and their drug-exposed infants: a review of the research literature Nurse home visits to maternal-child clients: a review of intervention research Progesterone for the prevention of preterm birth among women at increased risk: a systematic review and meta-analysis of randomized controlled trials Systematic review: the long-term effects of falsepositive mammograms
DARE abstracts are available without charge from: www.york.ac.uk/inst/crd/crddatabases.htm#DARE EVIDENCE-BASED REVIEWS FROM OTHER SOURCES Featured reviews: (1) Chu SY, Callaghan WM, Kim SY, Schmid CH, Lau J, England LJ, et al. Maternal obesity and risk of gestational diabetes mellitus. Diabetes Care 2007;30:2070 – 6. (2) Chu SY, Kim SY, Lau J, Schmid CH, Dietz PM, Callaghan WM, et al. Maternal obesity and risk of stillbirth: A meta-analysis. Am J Obstet Gynecol 2007;197:223– 8. (3) Chu SY, Kim SY, Schmid CH, Dietz PM, Callaghan WM, Lau J, et al. Maternal obesity and risk of cesarean delivery: A meta-analysis. Obes Rev 2007;8:385–94. Meta-analyses of observational studies assessed the effect of maternal obesity on risk for gestational diabetes mellitus (GDM), stillbirth, and cesarean delivery. All found heightened risk that rose as women’s weight categories increased. Because not all studies reported adjusted odds or adjusted for the same factors, crude 164
odds ratios were used in the primary meta-analyses; however, separate meta-analysis of available adjusted odds ratios yielded similar results. Overweight, obese, and severely obese women from 20 trials were two, four, and eight times more likely to develop GDM, respectively, compared to women of normal weight at the start of pregnancy. The odds of stillbirth were 1.47 and 2.07 for overweight and obese women from nine trials compared to those of normal weight. The odds of cesarean delivery were 1.46, 2.05, and 2.89, respectively, for overweight, obese, and severely obese women from 33 trials compared to normal weight women. Overweight and obese women without co-morbidities had 1.41 and 1.75 times higher odds of cesarean, respectively. Metaregression suggested that the relationship between obesity and outcomes did not vary by study characteristics. Comment: These studies clarify the magnitude of pregnancy risk related to excess weight. With 27% of US women overweight and 31% obese, pre-pregnancy weight loss could improve outcomes significantly. Featured review: Gourounti K, Sandall J. Admission cardiotocography versus intermittent auscultation of fetal heart rate: Effects on neonatal Apgar score on the rate of caesarean sections and on the rate of instrumental delivery—A systematic review. Int J Nurs Stud 2007; 44:1029 –35. A meta-analysis of three randomized controlled trials comprising 11,259 subjects evaluated effects of a 20minute continuous cardiotocography (CTG) assessment on hospital admission compared to intermittent auscultation of the fetal heart rate throughout labor without an initial period of continuous electronic monitoring. Outcomes compared were 5-minute Apgar scores and rates of cesarean and instrumental birth. The pooled relative risk of cesarean section was 20% higher, and that of instrumental delivery was 10% higher, in association with admission CTG compared to intermittent auscultation while there was no significant difference in 5-minute Apgar scores between the two groups. Comment: A CTG admission strip is routinely used to evaluate fetal well being for many women entering the hospital in labor. This review did not find a benefit for neonates and suggested increased risk of surgical or instrumental delivery associated with admission CTG compared to intermittent auscultation. Featured review: Kyrgiou M, Koliopoulos G, MartinHirsch P, Kehoe S, Flannelly G, Mitrou S, et al. Management of minor cervical cytological abnormalities: A systematic review and a meta-analysis of the literature. Cancer Treat Rev 2007;33:514 –20. The authors conducted a systematic review and metaanalysis of randomized controlled trials comparing outcomes for women with borderline or low-grade cervical cytology who received immediate referral for colposcopy Volume 53, No. 2, March/April 2008
to those managed with surveillance for up to 24 months. Compliance with return visits was also analyzed. Because of study heterogeneity, pooled analysis of all three trials was not possible for all outcomes. The incidence of human papillomavirus (HPV) and mild cervical dysplasia (CIN1) on biopsy was significantly higher in the immediate colposcopy group compared to the surveillance group at 24 months. There was no significant difference in incidence of moderate (CIN2) or worse dysplasia between these groups. However, by 24 months, the rate of adherence to a return appointment had decreased significantly for those in the surveillance group. The cytologic status is unknown for women lost to follow-up and introduces the possibility of biased estimates. Comment: Many minor cervical cytological abnormalities resolve spontaneously with time, especially in young women. However, some may progress to or mask invasive disease. At face value, the results of this meta-analysis favor surveillance; however, the risk to women lost to follow-up is uncertain. A risk– benefit analysis is needed to ascertain whether this risk exceeds those associated with potential over treatment of minor abnormalities. RECENT EVIDENCE-BASED REVIEWS ●
●
●
●
●
●
Choi H, Palmer MH, Park J. Meta-analysis of pelvic floor muscle training: Randomized controlled trials in incontinent women. Nurs Res 2007;56:226 –34. Friberg E, Orsini N, Mantzoros CS, Wolk A. Diabetes mellitus and risk of endometrial cancer: A metaanalysis. Diabetologia 2007;50:1365–74. Friedenson B. The BRCA1/2 pathway prevents hematologic cancers in addition to breast and ovarian cancers. BMC Cancer 2007;7:152. Available without charge from: www.biomedcentral.com/1471-2407/7/ 152 Golberg D, Szilagyi A, Graves L. Hyperemesis gravidarum and Helicobacter pylori infection: A systematic review. Obstet Gynecol 2007;110:695–703. Greiser CM, Greiser EM, Dören M. Menopausal hormone therapy and risk of ovarian cancer: Systematic review and meta-analysis. Hum Reprod Update 2007; 13:453– 63. Hatfield AS, Sanchez-Ramos L, Kaunitz AM. Sonographic cervical assessment to predict the success of
Journal of Midwifery & Women’s Health • www.jmwh.org
●
●
●
●
●
●
●
●
●
labor induction: A systematic review with metaanalysis. Am J Obstet Gynecol 2007;197:186 –92. Hind D, Ward S, De Nigris E, Simpson E, Carroll C, Wyld L. Hormonal therapies for early breast cancer: Systematic review and economic evaluation. Health Technol Assess 2007;11:1–152. Available without charge from: www.hta.nhsweb.nhs.uk/execsumm/ summ1126.htm Hofmeyr GJ, Duley L, Atallah A. Dietary calcium supplementation for prevention of pre-eclampsia and related problems: A systematic review and commentary. BJOG 2007;114:933– 43. Available without charge from: www.blackwell-synergy.com/doi/full/ 10.1111/j.1471-0528.2007.01389.x Larsson SC, Mantzoros CS, Wolk A. Diabetes mellitus and risk of breast cancer: A meta-analysis. Int J Cancer 2007;121:856 – 62. Luo ZC, An N, Xu HR, Larante A, Audibert F, Fraser WD. The effects and mechanisms of primiparity on the risk of pre-eclampsia: A systematic review. Paediatr Perinat Epidemiol 2007;(Suppl 1):36 – 45. Pitsouni E, Iavazzo C, Athanasiou S, Falagas ME. Single-dose azithromycin versus erythromycin or amoxicillin for Chlamydia trachomatis infection during pregnancy: A meta-analysis of randomised controlled trials. Int J Antimicrob Agents 2007;30:213–21. Press JZ, Klein MC, Kaczorowski J, Liston RM, von Dadelszen P. Does cesarean section reduce postpartum urinary incontinence? A systematic review. Birth 2007;34:228 –37. Romitti PA, Herring AM, Dennis LK, Wong-Gibbons DL. Meta-analysis: Pesticides and orofacial clefts. Cleft Palate Craniofac J 2007;44:358 – 65. Smith JS, Lindsay L, Hoots B, Keys J, Franceschi S, Winer R, et al. Human papillomavirus type distribution in invasive cervical cancer and high-grade cervical lesions: A meta-analysis update. Int J Cancer 2007; 121:621–32. Smith V, Devane D, Begley CM, Clarke M, Higgins S. A systematic review and quality assessment of systematic reviews of fetal fibronectin and transvaginal length for predicting preterm birth. Eur J Obstet Gynecol Reprod Biol 2007;133:2134 – 42.
R. Rima Jolivet, CNM, MSN, MPH, is Associate Director of Programs at Childbirth Connection, which works with health professionals and other audiences to promote evidence-based maternity care (http://www. childbirthconnection.org). E-mail: [email protected]
165
R. Rima Jolivet, CNM, MSN, MPH
Current Resources for Evidence-Based Practice, March/April 2008 Published simultaneously in Journal of Obstetric, Gynecologic & Neonatal Nursing 2008;37(2).
THE “DISCIPLINED SUBJECTIVITY” OF META-ANALYSIS A critique of the 2005 Cochrane review of randomized controlled trials comparing home-like versus hospital settings for birth1 has focused debate on methodologic challenges of meta-analysis. Criticism centered on criteria used to assess studies for inclusion and quality of the underlying studies, particularly whether they defined and controlled the treatment in each arm sufficiently to ensure trials offered valid comparisons between two discrete conditions.2 Meta-analyses can increase the statistical power and precision of estimates of effect by pooling data from studies that explore the same research question using comparable parameters. It is useful for clarifying results of multiple, similar small or conflicting studies. Pooling data does not, however, correct problems of quality in the contributing studies; it merely concentrates their unreliable conclusions. Judging which studies may be included in a metaanalysis is complicated and entails many decisions. Some focus on the quality of trials; others consider study design and format of the data. These decisions are made to satisfy the statistical assumptions of meta-analysis; nonetheless, they involve subjective judgments, may impact review conclusions, and are often not described explicitly. Voils et al.3 detail the methodologic considerations they faced when deciding which trials to include in a planned meta-analysis. To illustrate the “disciplined subjectivity” of meta-analysis and its impact on the resulting review, they describe the process of culling data from 29 trials for pooled analysis. After ensuring the statistical compatibility of study designs, methods to control or adjust for confounding, operationalization of variables, and metrics used to express the data, the authors report they had to exclude 73% to 87% of all observations, leaving very little of the original data to synthesize. In response to the critique of their Cochrane review on birth setting, Hodnett and Downe4 quote the Cochrane Handbook, noting that “much more research is needed to determine which criteria for validity assessment are important influences on study results.” Journal of Midwifery & Women’s Health • www.jmwh.org
1. Hodnett ED, Downe S, Edwards N, Walsh D. Home-like versus conventional institutional settings for birth. Cochrane Database Syst Rev 2005;1:CD000012. 2. Fahy K, Tracy SK. Critique of Cochrane systematic review of home-like setting for birth, Int J Evid Based Healthc 2007;5:360 – 4; Rejoinder, 367. 3. Voils CI, Barroso J, Haselblad V Sandelowski M. In or out? Methodological considerations for including and excluding findings from a meta-analysis of predictors of antiretroviral adherence in HIV-positive women. J Adv Nurs 2007;59:163–77. 4. Hodnett ED, Downe S. Response to critique of Cochrane systematic review of home-like setting for birth in the International Journal of Evidence-Based Healthcare. Int J Evid 2007;5:365– 6. FROM COCHRANE DATABASE OF SYSTEMATIC REVIEWS (CDSR), ISSUE 4, 2007 New Systematic Reviews ● ● ● ●
● ● ● ● ● ●
Amniotomy for shortening spontaneous labour Chinese herbal medicine for primary dysmenorrhoea Exercise for vasomotor menopausal symptoms Fundal pressure versus controlled cord traction as part of the active management of the third stage of labour Local cooling for relieving pain from perineal trauma sustained during childbirth Nutrient-enriched formula versus human breast milk for preterm infants following hospital discharge Phytoestrogens for vasomotor menopausal symptoms Prebiotics in infants for prevention of allergic disease and food hypersensitivity Probiotics in infants for prevention of allergic disease and food hypersensitivity Psychosocial and psychological interventions for treating postpartum depression
Updated Systematic Reviews ● ● ● ● ●
Antibiotics for incomplete abortion Continuous versus interrupted sutures for repair of episiotomy or second degree tears Copper containing, framed intra-uterine devices for contraception Danazol for pelvic pain associated with endometriosis Enemas during labour 163 1526-9523/08/$34.00 • doi:10.1016/j.jmwh.2007.12.013
Issued by Elsevier Inc.
● ● ● ● ●
Formula milk versus maternal breast milk for feeding preterm or low birth weight infants Hands and knees posture in late pregnancy or labour for fetal malposition (lateral or posterior) Nonsteroidal anti-inflammatory drugs for heavy menstrual bleeding Progestogens versus oestrogens and progestogens for irregular uterine bleeding associated with anovulation Venepuncture versus heel lance for blood sampling in term neonates
Cochrane reviews are available by subscription to The Cochrane Library, and review abstracts are available without charge. See www.thecochranelibrary.com FROM DATABASE OF ABSTRACTS OF REVIEWS OF EFFECTS (DARE) Recent Abstract Entries Assessing Quality of Systematic Reviews ● ●
●
● ●
●
An integrated review of the literature on demand feedings for preterm infants Improved effectiveness of partner notification for patients with sexually transmitted infections: systematic review Interventions to improve interactions between drug abusing mothers and their drug-exposed infants: a review of the research literature Nurse home visits to maternal-child clients: a review of intervention research Progesterone for the prevention of preterm birth among women at increased risk: a systematic review and meta-analysis of randomized controlled trials Systematic review: the long-term effects of falsepositive mammograms
DARE abstracts are available without charge from: www.york.ac.uk/inst/crd/crddatabases.htm#DARE EVIDENCE-BASED REVIEWS FROM OTHER SOURCES Featured reviews: (1) Chu SY, Callaghan WM, Kim SY, Schmid CH, Lau J, England LJ, et al. Maternal obesity and risk of gestational diabetes mellitus. Diabetes Care 2007;30:2070 – 6. (2) Chu SY, Kim SY, Lau J, Schmid CH, Dietz PM, Callaghan WM, et al. Maternal obesity and risk of stillbirth: A meta-analysis. Am J Obstet Gynecol 2007;197:223– 8. (3) Chu SY, Kim SY, Schmid CH, Dietz PM, Callaghan WM, Lau J, et al. Maternal obesity and risk of cesarean delivery: A meta-analysis. Obes Rev 2007;8:385–94. Meta-analyses of observational studies assessed the effect of maternal obesity on risk for gestational diabetes mellitus (GDM), stillbirth, and cesarean delivery. All found heightened risk that rose as women’s weight categories increased. Because not all studies reported adjusted odds or adjusted for the same factors, crude 164
odds ratios were used in the primary meta-analyses; however, separate meta-analysis of available adjusted odds ratios yielded similar results. Overweight, obese, and severely obese women from 20 trials were two, four, and eight times more likely to develop GDM, respectively, compared to women of normal weight at the start of pregnancy. The odds of stillbirth were 1.47 and 2.07 for overweight and obese women from nine trials compared to those of normal weight. The odds of cesarean delivery were 1.46, 2.05, and 2.89, respectively, for overweight, obese, and severely obese women from 33 trials compared to normal weight women. Overweight and obese women without co-morbidities had 1.41 and 1.75 times higher odds of cesarean, respectively. Metaregression suggested that the relationship between obesity and outcomes did not vary by study characteristics. Comment: These studies clarify the magnitude of pregnancy risk related to excess weight. With 27% of US women overweight and 31% obese, pre-pregnancy weight loss could improve outcomes significantly. Featured review: Gourounti K, Sandall J. Admission cardiotocography versus intermittent auscultation of fetal heart rate: Effects on neonatal Apgar score on the rate of caesarean sections and on the rate of instrumental delivery—A systematic review. Int J Nurs Stud 2007; 44:1029 –35. A meta-analysis of three randomized controlled trials comprising 11,259 subjects evaluated effects of a 20minute continuous cardiotocography (CTG) assessment on hospital admission compared to intermittent auscultation of the fetal heart rate throughout labor without an initial period of continuous electronic monitoring. Outcomes compared were 5-minute Apgar scores and rates of cesarean and instrumental birth. The pooled relative risk of cesarean section was 20% higher, and that of instrumental delivery was 10% higher, in association with admission CTG compared to intermittent auscultation while there was no significant difference in 5-minute Apgar scores between the two groups. Comment: A CTG admission strip is routinely used to evaluate fetal well being for many women entering the hospital in labor. This review did not find a benefit for neonates and suggested increased risk of surgical or instrumental delivery associated with admission CTG compared to intermittent auscultation. Featured review: Kyrgiou M, Koliopoulos G, MartinHirsch P, Kehoe S, Flannelly G, Mitrou S, et al. Management of minor cervical cytological abnormalities: A systematic review and a meta-analysis of the literature. Cancer Treat Rev 2007;33:514 –20. The authors conducted a systematic review and metaanalysis of randomized controlled trials comparing outcomes for women with borderline or low-grade cervical cytology who received immediate referral for colposcopy Volume 53, No. 2, March/April 2008
to those managed with surveillance for up to 24 months. Compliance with return visits was also analyzed. Because of study heterogeneity, pooled analysis of all three trials was not possible for all outcomes. The incidence of human papillomavirus (HPV) and mild cervical dysplasia (CIN1) on biopsy was significantly higher in the immediate colposcopy group compared to the surveillance group at 24 months. There was no significant difference in incidence of moderate (CIN2) or worse dysplasia between these groups. However, by 24 months, the rate of adherence to a return appointment had decreased significantly for those in the surveillance group. The cytologic status is unknown for women lost to follow-up and introduces the possibility of biased estimates. Comment: Many minor cervical cytological abnormalities resolve spontaneously with time, especially in young women. However, some may progress to or mask invasive disease. At face value, the results of this meta-analysis favor surveillance; however, the risk to women lost to follow-up is uncertain. A risk– benefit analysis is needed to ascertain whether this risk exceeds those associated with potential over treatment of minor abnormalities. RECENT EVIDENCE-BASED REVIEWS ●
●
●
●
●
●
Choi H, Palmer MH, Park J. Meta-analysis of pelvic floor muscle training: Randomized controlled trials in incontinent women. Nurs Res 2007;56:226 –34. Friberg E, Orsini N, Mantzoros CS, Wolk A. Diabetes mellitus and risk of endometrial cancer: A metaanalysis. Diabetologia 2007;50:1365–74. Friedenson B. The BRCA1/2 pathway prevents hematologic cancers in addition to breast and ovarian cancers. BMC Cancer 2007;7:152. Available without charge from: www.biomedcentral.com/1471-2407/7/ 152 Golberg D, Szilagyi A, Graves L. Hyperemesis gravidarum and Helicobacter pylori infection: A systematic review. Obstet Gynecol 2007;110:695–703. Greiser CM, Greiser EM, Dören M. Menopausal hormone therapy and risk of ovarian cancer: Systematic review and meta-analysis. Hum Reprod Update 2007; 13:453– 63. Hatfield AS, Sanchez-Ramos L, Kaunitz AM. Sonographic cervical assessment to predict the success of
Journal of Midwifery & Women’s Health • www.jmwh.org
●
●
●
●
●
●
●
●
●
labor induction: A systematic review with metaanalysis. Am J Obstet Gynecol 2007;197:186 –92. Hind D, Ward S, De Nigris E, Simpson E, Carroll C, Wyld L. Hormonal therapies for early breast cancer: Systematic review and economic evaluation. Health Technol Assess 2007;11:1–152. Available without charge from: www.hta.nhsweb.nhs.uk/execsumm/ summ1126.htm Hofmeyr GJ, Duley L, Atallah A. Dietary calcium supplementation for prevention of pre-eclampsia and related problems: A systematic review and commentary. BJOG 2007;114:933– 43. Available without charge from: www.blackwell-synergy.com/doi/full/ 10.1111/j.1471-0528.2007.01389.x Larsson SC, Mantzoros CS, Wolk A. Diabetes mellitus and risk of breast cancer: A meta-analysis. Int J Cancer 2007;121:856 – 62. Luo ZC, An N, Xu HR, Larante A, Audibert F, Fraser WD. The effects and mechanisms of primiparity on the risk of pre-eclampsia: A systematic review. Paediatr Perinat Epidemiol 2007;(Suppl 1):36 – 45. Pitsouni E, Iavazzo C, Athanasiou S, Falagas ME. Single-dose azithromycin versus erythromycin or amoxicillin for Chlamydia trachomatis infection during pregnancy: A meta-analysis of randomised controlled trials. Int J Antimicrob Agents 2007;30:213–21. Press JZ, Klein MC, Kaczorowski J, Liston RM, von Dadelszen P. Does cesarean section reduce postpartum urinary incontinence? A systematic review. Birth 2007;34:228 –37. Romitti PA, Herring AM, Dennis LK, Wong-Gibbons DL. Meta-analysis: Pesticides and orofacial clefts. Cleft Palate Craniofac J 2007;44:358 – 65. Smith JS, Lindsay L, Hoots B, Keys J, Franceschi S, Winer R, et al. Human papillomavirus type distribution in invasive cervical cancer and high-grade cervical lesions: A meta-analysis update. Int J Cancer 2007; 121:621–32. Smith V, Devane D, Begley CM, Clarke M, Higgins S. A systematic review and quality assessment of systematic reviews of fetal fibronectin and transvaginal length for predicting preterm birth. Eur J Obstet Gynecol Reprod Biol 2007;133:2134 – 42.
R. Rima Jolivet, CNM, MSN, MPH, is Associate Director of Programs at Childbirth Connection, which works with health professionals and other audiences to promote evidence-based maternity care (http://www. childbirthconnection.org). E-mail: [email protected]
165