Plain language summary
Preterm birth (PTB) is the primary cause of infant mortality worldwide; and infants who survive have a higher risk of child disability. A recent Cochrane Review concluded that there is strong evidence that omega-3 fatty acids, especially docosahexaenoic acid (DHA), reduce early PTB (EPTB, <34 weeks gestation) and PTB (<37 weeks gestation) by 42% and 11%, respectively. The aim of this study was to investigate whether DHA intake at baseline alone could identify pregnancies for which high dose DHA supplementation lowered risk of EPTB and PTB. This study used the results from two randomised clinical trials of DHA supplementation during pregnancy in which participants completed the DHA-Food Frequency Questionnaire (FFQ) before randomisation to 200mg/day or high dose DHA, i.e., 800mg/day or 1000mg/day. A total of 1400 participants were enrolled in the two trials. Results show that the DHA-FFQ predicted participants whose risk of EPTB and PTB was reduced by consuming a DHA supplement of 800mg/day or 1000mg/day compared to 200mg/day. In fact, participants who started the study with an average daily DHA intake of <150mg had a 64% lower rate of EPTB and a 24% lower rate of PTB if they were assigned to 800mg/day or 1000mg/day compared to 200mg/day DHA. Authors conclude that the DHA-FFQ identifies women who could benefit from high dose DHA supplementation at least as effectively as a blood measure of DHA but with far fewer barriers for clinical implementation.
Abstract
BACKGROUND Two randomized trials found women with low blood docosahexaenoic acid (DHA; an omega 3 fatty acid) had fewer early preterm births (<34 weeks gestation) if they were assigned to high dose DHA supplementation, however, there is currently no capacity for clinicians who care for pregnancies to obtain a blood assessment of DHA. Determining a way to identify women with low DHA intake whose risk could be lowered by high dose DHA supplementation is desired. OBJECTIVE To determine if assessing DHA intake can identify pregnancies that benefit from high dose DHA supplementation. STUDY DESIGN This secondary analysis used birth data from 1310 pregnant women who completed a 7-question food frequency questionnaire (DHA-FFQ) at 16.8 ± 2.5 weeks gestation that is validated to assess DHA status. They were then randomly assigned to a standard (200 mg/day) or high dose (800 or 1000 mg/day) DHA supplement for the remainder of pregnancy. Bayesian logistic regressions were fitted for early preterm birth and preterm birth as a function of DHA intake and assigned DHA dose. RESULTS Participants who consumed less than 150 mg/day DHA prior to 20 weeks' gestation (n = 810/1310, 58.1%) had a lower Bayesian posterior probability (pp) of early preterm birth if they were assigned to high dose DHA supplementation (1.4% vs 3.9%, pp = 0.99). The effect on preterm birth (<37 weeks) was also significant (11.3% vs 14.8%, pp = 0.97). CONCLUSION The DHA-FFQ can identify pregnancies that will benefit most from high dose DHA supplementation and reduce the risk of preterm birth. The DHA-FFQ is low burden to providers and patients and could be easily implemented in obstetrical practice.
Methodological quality
Jadad score
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Allocation concealment
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