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Maternal caffeine intake during pregnancy and risk of fetal growth restriction: a large prospective observational study

Boylan, S., Cade, J.E., Dolby, V.A., Greenwood, D.C., Hay, A.W.M., Kirk, S.F.L., Shires, S., Simpson, N., Thomas, J.D., Walker, J., White, K.L.M., Wild, C.P., Potdar, N., Konje, J.C., Taub, N., Charvill, J., Chipps, K.C., Kassam, S., Ghandi, C. and Cooke, M.S. (2008) Maternal caffeine intake during pregnancy and risk of fetal growth restriction: a large prospective observational study. BMJ, 337 (a2332). pp. 1334-1337. ISSN 0959-8146


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Objective: To examine the association of maternal caffeine intake with fetal growth restriction. Design Prospective longitudinal observational study.

Setting: Two large UK hospital maternity units.

Participants: 2635 low risk pregnant women recruited between 8-12 weeks of pregnancy.

Investigations: Quantification of total caffeine intake from 4 weeks before conception and throughout pregnancy was undertaken with a validated caffeine assessment tool. Caffeine half life (proxy for clearance) was determined by measuring caffeine in saliva after a caffeine challenge. Smoking and alcohol were assessed by self reported status and by measuring salivary cotinine concentrations.

Main outcome measures: Fetal growth restriction, as defined by customised birth weight centile, adjusted for alcohol intake and salivary cotinine concentrations.

Results: Caffeine consumption throughout pregnancy was associated with an increased risk of fetal growth restriction (odds ratios 1.2 (95% CI 0.9 to 1.6) for 100-199 mg/day, 1.5 (1.1 to 2.1) for 200-299 mg/day, and 1.4 (1.0 to 2.0) for >300 mg/day compared with <100 mg/day; test for trend P<0.001). Mean caffeine consumption decreased in the first trimester and increased in the third. The association between caffeine and fetal growth restriction was stronger in women with a faster compared to a slower caffeine clearance (test for interaction, P=0.06).

Conclusions: Caffeine consumption during pregnancy was associated with an increased risk of fetal growth restriction and this association continued throughout pregnancy. Sensible advice would be to reduce caffeine intake before conception and throughout pregnancy.

Item Type: Article
Copyright, Publisher and Additional Information: Corrections: During some recent new analysis of the data for this study by the CARE Study Group, the authors noticed an inconsistency in the data recording for caffeine intake (BMJ 2008;337:a2332, doi:10.1136/bmj.a2332). This meant that a small proportion of women had been wrongly allocated zero caffeine intake for instant coffee even though they might have consumed instant coffee. The authors have recalculated the corrected total caffeine values, resulting in small changes to the results. In table 3 in the full online version (and the single table in the print version), the adjusted odds ratios (95% confidence intervals) for the risk of fetal growth restriction according to caffeine intake averaged over pregnancy should read: for caffeine intake 100-199 mg/day, 1.1 (0.8 to 1.5) [not 1.2 (0.9 to 1.6)] ; 200-299 mg/day, 1.3 (0.9 to 1.8) [not 1.5 (1.1 to 2.1)]; 300 mg/day, 1.5 (1.0 to 2.1) [not 1.4 (1.1 to 2.0)]; and the P value for the test for trend (0.02) remains the same. At specific time points in table 3 and in the analysis reported in table 4, the new analysis resulted in only modest changes. In the figure the "best-fitting" curve remains closely similar to that in the published version. And the mean percentage of caffeine is now 21% from coffee and 58% from tea (not 14% and 62% respectively, as given in the main text). These revised results do not change the interpretation of the findings or the strength of association. Readers requiring more detailed information should contact the authors (Professor Janet Cade, j.e.cade@leeds.ac.uk).
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Leeds Institute of Genetics, Health and Therapeutics (LIGHT) > Division of Epidemiology & Biostatistics (Leeds)
Depositing User: Repository Officer
Date Deposited: 15 Dec 2008 13:06
Last Modified: 05 Jun 2014 13:09
Published Version: http://dx.doi.org/10.1136/bmj.a2332
Status: Published
Publisher: BMJ Publishing
Refereed: Yes
Identification Number: 10.1136/bmj.a2332
URI: http://eprints.whiterose.ac.uk/id/eprint/4997

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