Cochrane for Clinicians
Putting Evidence into Practice
Impact of Antenatal Dietary Education and Supplementation on Maternal and Infant Health Outcomes
Am Fam Physician. 2016 Apr 1;93(7):557-558.
Does antenatal dietary education or supplementation to increase energy and protein intake in pregnancy impact maternal and infant health outcomes?
Antenatal dietary education appears to decrease the rate of preterm birth and increase infant birth weight among undernourished women. Providing balanced energy and protein supplements to pregnant women decreases the risk of stillbirth, low birth weight, and having an infant that is small for gestational age (number needed to treat [NNT] = 28). The use of high-protein supplements does not improve any outcomes and may cause fetal harm. Neither dietary advice nor supplementation affects maternal outcomes. (Strength of Recommendation: B, based on inconsistent or limited-quality patient-oriented evidence.)
As of 2010, the infant mortality rate in the United States ranked number 26 out of 29 developed nations surveyed.1 Preterm births and low birth weight are important factors that influence infant mortality. In the United States, 11% of births are preterm (i.e., born before 37 weeks of gestation) and 8% of infants are born at a low birth weight (i.e., less than 2,500 g [5 lb, 8 oz]).2 Reducing the incidence of low birth weight and preterm births is a stated objective of Healthy People 2020.3 The authors of this Cochrane review hoped to determine whether providing nutritional counseling to pregnant women can improve these outcomes.
This Cochrane review includes 17 randomized controlled trials with a total of 9,030 pregnant women. The variables studied were advice to increase caloric intake, advice to increase protein intake, or being given dietary supplements. There were four categories of trials: (1) trials that provided specific nutritional advice to increase dietary energy and protein intake, (2) trials that provided balanced energy and protein supplements (i.e., less than 25% of total calories from protein), (3) trials that provided high-protein supplements (i.e., more than 25% of total calories from protein), and (4) trials that provided isocaloric protein supplements. Seven of the included trials were conducted in high-income countries such as the United States and the United Kingdom, although more than two-thirds of the included women were considered undernourished or nutritionally at risk. Several studies had unclear or high risk of bias. The quality of the studies was rated low to moderate.
Antenatal dietary education affected undernourished women more than any other group. Undernourished women are those with a body mass index of less than 18 kg per m2, with stunted height, or with micro- and macronutrient deficiencies. In this group, birth weight was significantly increased (mean difference [MD] = 489.76 g; 95% confidence interval [CI], 427.93 to 551.59), whereas rates of preterm birth (relative risk [RR] = 0.46; 95% CI, 0.21 to 0.98; P < .05) and low birth weight were decreased. However, these improvements did not translate into positive effects on neonatal death (defined as death in the first 28 days after birth), stillbirth, or being small for gestational age; these indices remained unchanged.
Providing balanced energy and protein supplements decreased the risk of stillbirth (RR = 0.60; 95% CI, 0.39 to 0.94) and being small for gestational age (RR = 0.79; 95% CI, 0.69 to 0.90; NNT = 28; 95% CI, 19 to 59), and increased birth weight (MD = 40.96 g; 95% CI, 4.66 to 77.26). These trials did not demonstrate any change in the rates of preterm birth or neonatal death. High-protein supplements had no effect on birth weight or preterm birth, but they nonsignificantly increased the rates of stillbirth and neonatal death. High-protein supplements also increased the number of infants who were small for gestational age (RR = 1.58; 95% CI, 1.03 to 2.41; number needed to harm = 15; 95% CI, 6 to 250). Use of isocaloric protein supplements demonstrated no benefit or harm to the women or their babies.
Current guidelines recommend that clinicians counsel pregnant women on nutrition and weight at every visit from preconception through postpartum, although specific caloric and protein recommendations are lacking.4 Evidence-based reviews recommend increasing daily energy intake by 300 to 400 calories in the second and third trimesters with no mention of protein intake.5 Nutritional supplements other than folic acid are not recommended. Although additional better-quality research is needed, this review provides some guidance to the family physician on why such counseling matters.
editor's note: The number needed to treat and number needed to harm reported in this Cochrane for Clinicians were calculated by AFP medical editors based on raw data provided in the original Cochrane review.
The practice recommendations in this activity are available at http://summaries.cochrane.org/CD000032.
Ota E, Hori H, Mori R, Tobe-Gai R, Farrar D. Antenatal dietary education and supplementation to increase energy and protein intake. Cochrane Database Syst Rev. 2015;(6):CD000032.
REFERENCESshow all references
1. MacDorman MF, Matthews TJ, Mohangoo AD, Zeitlin J. International comparisons of infant mortality and related factors: United States and Europe, 2010. Natl Vital Stat Rep. 2014;63(5):1–6....
2. Martin JA, Hamilton BE, Osterman MJ, Curtin SC, Matthews TJ. Births: final data for 2013. Natl Vital Stat Rep. 2015;64(1):1–65.
3. U.S. Department of Health and Human Services. Maternal, infant, and child health. HealthyPeople.gov. http://www.healthypeople.gov/2020/topics-objectives/topic/maternal-infant-and-child-health/objectives. Accessed August 24, 2015.
4. Akkerman D, Cleland L, Croft G, et al.; Institute for Clinical Systems Improvement. Routine prenatal care. Updated July 2012. https://www.icsi.org/_asset/13n9y4/Prenatal.pdf. Accessed February 29, 2016.
5. Kirkham C, Harris S, Grzybowski S. Evidence-based prenatal care. Part I. General prenatal care and counseling issues. Am Fam Physician. 2005;71(7):1307–1316.
These are summaries of reviews from the Cochrane Library.
This series is coordinated by Corey D. Fogleman, MD, Assistant Medical Editor.
A collection of Cochrane for Clinicians published in AFP is available at https://www.aafp.org/afp/cochrane.
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