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A Randomized Trial of Docosahexaenoic Acid Supplementation During the Third Trimester of Pregnancy

Smuts, Cornelius M. PhD; Huang, Minzhao MD, PhD; Mundy, David MD; Plasse, Terry MD; Major, Stacey MS; Carlson, Susan E. PhD

Original Research

OBJECTIVE To hypothesize that higher intake of docosahexaenoic acid, an n-3 long chain polyunsaturated fatty acid, would increase duration of gestation and birth weight in US women.

METHODS This was a randomized, double-blind, controlled, clinical trial. Subjects were enrolled in an ambulatory clinic where they received prenatal care. This was a population-based sample. Most subjects received government assistance for medical care and most were black (73%). Subjects were enrolled between the 24th and 28th week of pregnancy and consumed docosahexaenoic acid (33 or 133 mg) from eggs until parturition. Gestational age and birth weight were the main study outcomes. Infant length and head circumference, preterm birth, and low birth weight were secondary outcomes.

RESULTS Eighty-three percent of subjects completed the study (291 of 350 enrolled). No subject was discontinued for an adverse event. After controlling for important predefined risk factors and confounding variables, gestation increased by 6.0 ± 2.3 days (P = .009) in the higher docosahexaenoic acid group. Birth weight, length, and head circumference increased, but did not reach statistical significance (P = .06–.18), although the increases could be clinically important indications of enhanced intrauterine growth. No safety concerns were raised by the study.

CONCLUSION Duration of gestation increased significantly when docosahexaenoic acid intake was increased during the last trimester of pregnancy. The increase in gestation was similar to that reported for interventions with much larger amounts of n-3 long chain polyunsaturated fatty acids

Dietary docosahexaenoic acid supplementation during the third trimester of pregnancy extends gestation.

Department of Dietetics and Nutrition, University of Kansas Medical Center, Kansas City, Kansas; Department of Obstetrics and Gynecology, University of Missouri–Kansas City, Kansas City, Missouri; and AQUAL Clinical Research Services Inc., Marlborough, Massachusetts.

CMS is currently affiliated with the Medical Research Council, Tygerberg, South Africa.

This work was carried out at the University of Kansas Medical Center, Kansas City, Kansas, and the University of Missouri, Kansas City, Missouri.

The authors are grateful to Mary Van Elswyk, Deanna McCarthy, and OmegaTech Inc. for support of this study, and to Nadene Hausmann of AQUAL Clinical Research Services Inc., whose outstanding organizational skills and oversight were invaluable to the study team. Minati Dhar and Amanda Schraegle provided excellent technical help. The authors also thank the faculty and staff of Truman Medical Center for assisting on many occasions.

Financial Disclosure Grant support was received from OmegaTech Inc., Boulder, Colorado, for personnel salaries and to run the laboratory.

Address reprint requests to: Susan E. Carlson, PhD, University of Kansas Medical Center, Department of Dietetics and Nutrition, 4019 Delp, 3901 Rainbow Boulevard, Kansas City, KS 66160; E-mail:

Received May 13, 2002. Received in revised form August 27, 2002. Accepted September 5, 2002.

© 2003 The American College of Obstetricians and Gynecologists