Antioxidant-rich dietary intervention for improving asthma control in pregnancies complicated by asthma: study protocol for a randomized controlled trialReport as inadecuate

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, 15:108

First Online: 04 April 2014Received: 28 August 2013Accepted: 24 March 2014DOI: 10.1186-1745-6215-15-108

Cite this article as: Grieger, J.A., Wood, L.G. & Clifton, V.L. Trials 2014 15: 108. doi:10.1186-1745-6215-15-108


BackgroundAsthma is the most prevalent chronic disease to complicate pregnancies worldwide, affecting around 12% of pregnant women in Australia. Oxidative stress and inflammation manifest during pregnancy; however asthma in pregnancies further intensifies oxidative stress. Consumption of antioxidant-rich foods has been shown to be beneficial for asthma control in non-pregnant asthmatic adults. It has not been investigated whether antioxidant-rich foods can improve the elevated oxidative stress that occurs with asthma in pregnancy, thereby improving asthma control. The primary aim of this study is to determine whether increased consumption of antioxidant-rich foods for 12 weeks will improve maternal asthma control, compared to standard dietary intake during pregnancy.

Methods-designA 12 week, parallel randomized controlled trial will be conducted. One hundred and sixty eight pregnant women with mild, moderate, or severe asthma, currently using inhaled corticosteroids, and with poor diet quality, will be recruited at approximately12 weeks gestation. Following a 4 week run-in period, women will be randomized to either a 12 week antioxidant intervention increased consumption of antioxidant-rich foods ≥5 servings-day vegetables, ≥2 servings-day fruit, ≥8 ½ servings-day grains mostly wholegrains, 3–4 serving-week lean meat or standard pregnancy care. The primary outcome is asthma control score decrease of 0.5, the minimally clinically significant change. Secondary outcomes include plasma antioxidants, markers of oxidative stress, and time to, and number of, exacerbations. With two-tailed t-tests at 80% power, a sample size of 52 completions per group is required. Allowing for a 78% retention including a 20% removal of women from the analysis due to non-compliance, we will recruit 168 women.

DiscussionIt is expected that this 12 week study will improve asthma control. This is significant because asthma is the most prevalent condition to complicate pregnancies and contributes to poor maternal, neonatal and infant health outcomes. Our research will provide the first evidence to show that, in pregnancy, consumption of antioxidant-rich foods is a key modifier of clinical asthma status. This research is crucial for contributing to the evidence base to inform future guidelines given existing clinical and research gaps.

Trial registrationACTRN12613000301763

KeywordsAntioxidants Pregnancy Asthma Asthma control Diet AbbreviationsACQ6asthma control questionnaire 6

AMEAasthma management and education advice

ANCTRAustralia and New Zealand Clinical Trials Registry

BPblood pressure

ELISAenzyme-linked immunosorbent assay

FENOfraction of exhaled nitric oxide

FEV1forced expiratory volume in 1 second

FFQfood frequency questionnaire

F + Vfruit and vegetable

ICSinhaled corticosteroids


IUGRintrauterine growth restriction

LBWlow birth weight

LGAlarge for gestational age

LMHLyell McEwin Hospital

RCTrandomized controlled trial

SGAsmall for gestational age

TNFtumor necrosis factor.

Electronic supplementary materialThe online version of this article doi:10.1186-1745-6215-15-108 contains supplementary material, which is available to authorized users.

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Author: Jessica A Grieger - Lisa G Wood - Vicki L Clifton


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