What is the question?

• The question is: What is the relationship between maternal diet during pregnancy on flavor transfer to amniotic fluid, children’s behavioral response, and dietary intake?

What is the answer to the question?

• Limited but consistent evidence indicates that flavors contained in the foods and beverages in the maternal diet during pregnancy can transfer to and flavor amniotic fluid, and fetal exposure to these flavors increases acceptance of the exposed flavor during infancy and potentially childhood. Flavor transfer to amniotic fluid occurred after pregnant mothers ingested alcohol, anise, carrot, or garlic. These findings may not be generalizable to all foods and beverages in the maternal diet during pregnancy.
• A conclusion cannot be drawn to describe the relationship between maternal diet during pregnancy and children’s dietary intake. Based upon current evidence, it is not feasible to isolate the influence of maternal diet during pregnancy on subsequent infant and child dietary intake.

Why was this question asked? 

• This important public health question was identified and prioritized as part of the U.S. Department of Agriculture and Department of Health and Human Services Pregnancy and Birth to 24 Months Project.

How was this question answered? 

• A team of staff from the Nutrition Evidence Systematic Review conducted a systematic review in collaboration with a group of experts called a Technical Expert Collaborative.

What is the population of interest? 

• Generally healthy pregnant women and their healthy infants and toddlers who were ages 0-24 months. The child’s food acceptability and dietary intake was examined through the lifespan.

What evidence was found? 

• This review includes 11 studies published since 1995
• These studies compared maternal diet during pregnancy and: 1) changes in the flavor (odor) of amniotic fluid, 2) how experiences with flavors in amniotic fluid impact the infant’s or child’s behavioral responses during subsequent exposure to the flavor (or odor), and/or 3) dietary intake during childhood.
• The flavor of a food is a complex combination of tastes (sweet, sour, salty, bitter, umami), textures, and volatile odors, which travel to the olfactory receptors when foods or liquids are in the mouth and when odor volatiles are inhaled through the nose.
• Flavors contained in foods or beverages in the maternal diet during pregnancy studied include: alcohol, anise, carrot, and garlic.
• One study showed that when mothers ate garlic during pregnancy there was a change in amniotic fluid odor, as detected by a sensory panel of adults.
• Six studies focused on the relationship between maternal ingestion of particular flavors during pregnancy and their child’s behavioral response to the flavor, during smelling or eating. 
  • Four studies showed that maternal intake of garlic, anise or alcohol flavors during pregnancy resulted in greater acceptance or more arousal by the infants when re-exposed to the odor, three hours to 10 days after birth compared to infants whose mothers did not ingest the flavor during pregnancy. 
  • One study demonstrated that after weaning, infants whose mothers drank carrot juice during pregnancy exhibited greater acceptance of carrot-flavored cereal relative to plain cereal when compared to infants whose mothers avoided carrot juice or carrots during pregnancy.   
  • One study focused on the relationship between maternal ingestion of garlic during pregnancy and the child’s acceptance of garlic when they were 8- to 9-years-old. Children of mothers who consumed garlic during the last 4 weeks of pregnancy ate more garlic-flavored potatoes when compared to children of mothers who did not consume garlic during the last 4 weeks of pregnancy.
• For garlic, the convergence of findings from 3 separate studies revealed: 1) garlic ingestion by pregnant mothers in the second trimester alters the odor of amniotic fluid; 2) newborns respond differently to the odor of garlic, if their mothers ate garlic during the last month of pregnancy; and 3) experiences with garlic flavor during the last month of pregnancy resulted in greater child acceptance of garlic-flavored foods by the child 8-9 years later.
• Four studies found an association between maternal diet during pregnancy and diet quality or dietary patterns of children 9 months to 4 years of age. While this is important research, these studies cannot directly address the impact of maternal diet strictly during pregnancy on their children’s dietary intake due to serious methodological limitations. These limitations include: similarities between maternal prenatal and postpartum diet, maternal influences on what foods are offered to children, and maternal and child dietary measures based on maternal report without direct measurements of children’s acceptance of foods or flavors.

How up-to-date is this systematic review? 

• This review includes literature from 01/1980 to 06/2017.

Background

• This systematic review was conducted as part of the U.S. Department of Agriculture and Department of Health and Human Services Pregnancy and Birth to 24 Months Project.
• The goal of this systematic review was to examine the following question: what is the relationship between maternal diet during pregnancy on flavor transfer to amniotic fluid, children’s behavioral response, and dietary intake?
• The flavor of a food is a complex combination of tastes (sweet, sour, salty, bitter, umami), textures, and volatile odors, which travel to the olfactory receptors when foods or liquids are in the mouth and when odor volatiles are inhaled through the nose.  

Conclusion Statement and Grade

• Limited but consistent evidence indicates that flavors contained in the foods and beverages in the maternal diet during pregnancy can transfer to and flavor amniotic fluid, and fetal exposure to these flavors increases acceptance of the exposed flavor during infancy and potentially childhood. Flavor transfer to amniotic fluid occurred after pregnant mothers ingested alcohol, anise, carrot, or garlic. These findings may not be generalizable to all foods and beverages in the maternal diet during pregnancy. Grade: Limited
• A conclusion cannot be drawn to describe the relationship between maternal diet during pregnancy and children's dietary intake. Based on current evidence, it is not feasible to isolate the influence of maternal diet during pregnancy on subsequent infant and child dietary intake. Grade: Grade Not Assignable

Methods 

• The systematic review was conducted by a team of staff from the Nutrition Evidence Systematic Review in collaboration with a Technical Expert Collaborative.
• Literature searches were conducted using 10 databases to identify studies that evaluated the relationship among maternal diet during pregnancy, amniotic fluid flavor; and children’s food acceptability and overall dietary intake. A manual search was conducted to identify articles that may not have been included in the electronic databases searched. Articles were screened by two authors independently for inclusion based on pre-determined criteria.
• Data from each included article were extracted, risks of bias were assessed, and both were checked for accuracy. The body of evidence was qualitatively synthesized, a conclusion statement was developed, and the strength of the evidence (grade) was assessed using pre-established criteria including evaluation of the internal validity/risk of bias, adequacy, consistency, impact, and generalizability of available evidence.

Summary of Evidence

• This systematic review includes 11 studies
• The studies used multiple approaches to examine the relationship between maternal ingestion of alcohol, anise, carrot, and garlic during pregnancy and: 1) changes in the flavor (odor) of amniotic fluid, 2) how experiences with flavors in amniotic fluid impact the infant’s or child’s behavioral responses during subsequent exposure to the flavor (or odor), and/or 3) dietary intake during childhood.
• One study demonstrated maternal ingestion of garlic during pregnancy resulted in a change in amniotic fluid odor, as detected by a sensory panel of adults.
• Six studies focused on the relationship between maternal ingestion of particular flavors during pregnancy and their child’s behavioral response to the flavor, during smelling or eating. 
• Four studies indicated that maternal intake of garlic, anise or alcohol flavors during pregnancy resulted in greater acceptance or more arousal by the infants when re-exposed to the respective odor from three hours to 10 days after birth compared to infants whose mothers did not ingest the respective flavor during pregnancy. 
• One study demonstrated that after weaning, infants whose mothers consumed carrot juice during pregnancy exhibited greater acceptance of carrot-flavored cereal relative to plain cereal compared to infants whose mothers avoided carrot juice or carrots during pregnancy.   
• One study found that 8- to 9-year-old children of mothers who consumed garlic during the last 4 weeks of pregnancy ate more garlic-flavored potatoes when compared to children of mothers who were randomly assigned to not consume garlic during the last 4 weeks of pregnancy. 
• For at least one commonly consumed flavor (garlic), the convergence of findings from 3 separate studies revealed: 1) garlic ingestion by pregnant mothers in the second trimester alters the sensory properties of amniotic fluid; 2) newborns respond differently to the odor of garlic, if their mothers ate garlic during the last month of pregnancy; and 3) experiences with garlic flavor during the last month of pregnancy resulted in greater child acceptance of a garlic-flavored food by the child 8-9 years later.
• Four longitudinal cohort studies found an association between maternal diet during pregnancy and diet quality or dietary patterns of children 9 months to 4 years of age. While this is important research, these studies cannot directly address the impact of maternal diet strictly during pregnancy on their children’s dietary intake due to serious methodological limitations. These limitations include: similarities between maternal prenatal and postpartum diet, maternal influences on what foods are offered to children, and maternal and child dietary measures based on maternal report without direct measurements of children’s acceptance of foods or flavors.