For Peer Review Only Journal: BMJ Open
Total Page:16
File Type:pdf, Size:1020Kb
BMJ Open BMJ Open: first published as 10.1136/bmjopen-2016-015410 on 3 August 2017. Downloaded from Low alcohol consumption and pregnancy and childhood outcomes: time to change guidelines indicating apparently ‘safe’ levels of alcohol during pregnancy? A systematic review and meta-analyses. For peer review only Journal: BMJ Open Manuscript ID bmjopen-2016-015410 Article Type: Research Date Submitted by the Author: 02-Dec-2016 Complete List of Authors: Mamluk, Loubaba; University of Bristol School of Social and Community Medicine, IEU Edwards, Hannah; University of Bristol, School of Social and Community Medicine Savovic, Jelena; University of Bristol, NIHR CLAHRC West Leach, Verity; University of Bristol Jones, Tim; NIHR CLAHRC West, Moore, Theresa; NIHR CLAHRC West Ijaz , Sharea ; NIHR CLAHRC West Lewis, Sarah; University of Bristol, School of Social and Community Medicine Donovan, Jenny; NIHR CLAHRC West Lawlor, Debbie; Department of Social Medicine, University of Bristol, MRC http://bmjopen.bmj.com/ Integrative Epidemiology Unit Davey Smith, George; University of Bristol, Social Medicine Fraser, Abigail; University of Bristol, MRC Integrative Epidemiology Unit Zuccolo, Luisa; University of Bristol, School of Social and Community Medicine <b>Primary Subject Epidemiology Heading</b>: on October 2, 2021 by guest. Protected copyright. Secondary Subject Heading: Reproductive medicine Keywords: PAEDIATRICS, EPIDEMIOLOGY, Maternal medicine < OBSTETRICS For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 1 of 47 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2016-015410 on 3 August 2017. Downloaded from 1 2 3 Systematic Review & Meta-analysis 4 5 6 7 Title: Low alcohol consumption and pregnancy and childhood outcomes: time to change 8 9 guidelines indicating apparently ‘safe’ levels of alcohol during pregnancy? A systematic review 10 11 and meta-analyses. 12 13 14 15 Running tittle:For Low alcohol peer consumption reviewand pregnancy and childhood only outcomes. 16 17 18 19 Authors: Loubaba Mamluk PhD1,2,3, Hannah B Edwards MSc2,3, Jelena Savović PhD2,3, Verity 20 21 Leach PhD 2,3, Timothy Jones PhD 2,3, Theresa HM Moore MSc 2,3, Sharea Ijaz PhD 2,3, Sarah 22 23 J. Lewis PhD 2, Jenny L. Donovan PhD 2,3, Deborah A. Lawlor PhD 1,2,3, George Davey Smith 24 25 PhD 1,2, Abigail Fraser PhD*1,2, Luisa Zuccolo PhD*1,2 26 27 * Joint Last Authors 28 29 30 31 32 Author addresses: Hannah B Edwards, Jelena Savovic, Verity Leach, Timothy Jones, 33 34 Theresa HM Moore, Sharea Ijaz, and Jenny L. Donovan: NIHR CLAHRC West, University http://bmjopen.bmj.com/ 35 36 Hospitals Bristol, NHS Foundation Trust, 9th Floor, Whitefriars, Lewins Mead, Bristol, BS1 37 38 2NT, United Kingdom. Sarah J. Lewis, Deborah A. Lawlor, George Davey Smith, Abigail 39 40 Fraser, and Luisa Zuccolo: MRC Integrative Epidemiology Unit, School of Social and 41 42 Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, on October 2, 2021 by guest. Protected copyright. 43 44 United Kingdom. 45 46 47 Corresponding author: Loubaba Mamluk, MRC Integrative Epidemiology Unit, School of 48 49 Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol 50 51 BS8 2BN, United Kingdom. NIHR CLAHRC West, University Hospitals Bristol 52 53 NHS Foundation Trust, 9th Floor, Whitefriars, Lewins Mead Bristol, BS1 2NT. United Kingdom 54 55 T+44 (0)117 3313378, [email protected] 56 57 1 58 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 2 of 47 BMJ Open: first published as 10.1136/bmjopen-2016-015410 on 3 August 2017. Downloaded from 1 2 3 Author affiliations: 4 5 6 1 MRC Integrative Epidemiology Unit at the University of Bristol, Bristol 7 8 2 School of Social and Community Medicine, University of Bristol, Bristol 9 10 3 NIHR CLAHRC West, University Hospitals Bristol NHS Foundation Trust, Bristol 11 12 Word Count: 3257 13 Figures: 3 14 Tables: 3 15 SupplementaryFor Tables: 3peer review only 16 Supplementary Figures 3 17 Number of references: 53 18 19 20 21 What this paper adds 22 23 What is already known on this subject 24 Until recently UK guidelines advised women to avoid drinking alcohol while trying to conceive, and in the 25 first trimester, but at the same time indicated that consumption should be restricted to within “1 to 2 UK 26 27 units, once or twice a week. 28 Despite the guidance on light drinking versus abstinence being the point of confusion for health 29 professionals and pregnant women and contributing to inconsistent guidance and advice, previous 30 31 reviews have reported on a range of “low/moderate” alcohol consumption levels in pregnancy and have 32 not focused specifically on the threshold that current UK guidelines refer to. 33 34 Additionally, they did not specifically seek out study designs that reduce the impact of confounding and http://bmjopen.bmj.com/ 35 other forms of bias on the effect estimates. 36 37 What this study adds 38 We examined the effects of light alcohol consumption during pregnancy using the best quality evidence by 39 only including studies with prospective assessment of exposure and prioritising results adjusted for main 40 confounders. 41 We uniquely sought to include alternative study designs to further improve causal inference alongside 42 on October 2, 2021 by guest. Protected copyright. 43 standard analytical approaches. 44 45 We found very few studies employing either standard or alternative analytical approaches that answered 46 the research question focussed on the specific range of exposure. Pooled estimates from these studies 47 provided some evidence that even light alcohol consumption in pregnancy is associated with risk of 48 49 preterm delivery and small for gestational age. 50 We found very little evidence to support recommendations of a 32g alcohol/week limit with respect to most 51 52 outcomes. 53 54 55 56 57 2 58 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 3 of 47 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2016-015410 on 3 August 2017. Downloaded from 1 2 3 Abstract: 4 5 Objectives: To determine the effects of low-to-moderate levels of maternal alcohol 6 7 consumption in pregnancy on pregnancy and longer-term offspring outcomes. 8 9 Search Strategy: Medline, Embase, Web of Science, and Psychinfo from inception to 11-07- 10 11 2016. 12 13 Selection Criteria: Prospective observational studies, negative control and quasi- 14 15 experimental studiesFor of pregnant peer women estimatingreview effects of lightonly drinking in pregnancy 16 17 (≤32g/week) versus abstaining. Pregnancy outcomes such as birth weight, and features of 18 19 fetal alcohol syndrome were examined. 20 21 Data Collection and Analysis: One reviewer extracted data and another checked extracted 22 23 data. Random effects meta-analyses were performed where applicable, and a narrative 24 25 summary of findings was carried out otherwise. 26 27 Main Results: 24 cohort and two quasi-experimental studies were included. With the 28 29 exception of birth size and gestational age, there was insufficient data to meta-analyse or 30 31 make robust conclusions. Being small-for-gestational-age (SGA) and preterm birth odds were 32 33 higher for babies whose mothers consumed up to 32g/week versus none, but estimates for 34 http://bmjopen.bmj.com/ 35 preterm birth included the null value: summary odd ratios (OR) 108, 95% confidence intervals 36 37 (CI) (102 to 114), I2 0%, OR 110, 95%CI (095 to128), I2 60.2%, respectively. 38 39 40 Conclusion: Evidence of the effects of drinking <=32g/w in pregnancy is sparse. As there 41 was some evidence that even light prenatal alcohol consumption is associated with being 42 on October 2, 2021 by guest. Protected copyright. 43 44 SGA and preterm delivery, guidance could advise abstention as a precautionary principle, but 45 46 should explain the paucity of evidence. 47 48 Keywords: Alcohol, pregnancy, systematic review. 49 50 51 52 53 54 55 56 57 3 58 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 4 of 47 BMJ Open: first published as 10.1136/bmjopen-2016-015410 on 3 August 2017. Downloaded from 1 2 3 Strengths and Limitations of this study: 4 5 Strengths 6 7 - Completeness of searches with a focused research question aimed at informing alcohol in 8 9 pregnancy guidelines. 10 11 - Biases minimised by only including those with prospective assessment of exposure and 12 13 prioritising results adjusted for main confounders. 14 15 For peer review only 16 - Unique effort to include alternative study designs to further improve causal inference 17 18 alongside standard analytical approaches. 19 20 Limitations 21 22 - Limitation of results on the effects of light drinking in pregnancy from standard analytical 23 24 approaches is bias due to residual confounding. 25 26 - The inclusion of only English language studies may have led to missing some studies, 27 28 however there is little evidence that exclusion of non-English language studies leads to 29 30 systematic bias in systematic reviews of conventional medicine. 31 32 - We could not pool eligible studies for various reasons (e.g. too few studies, lack of 33 34 standard errors) http://bmjopen.bmj.com/ 35 36 37 38 39 40 41 42 on October 2, 2021 by guest. Protected copyright. 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 4 58 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 5 of 47 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2016-015410 on 3 August 2017.