Maternal diet during pregnancy is thought to be one of the most influential factors on child health and development. However, dietary interventions during this period may miss a critical window to improve health during childhood, as well as adult life.
In a recent series of articles in The Lancet, researchers address the significance of nutrition in the preconception period, or the time before a woman becomes pregnant. The series of three articles challenges the current perspective of the preconception period. Currently defined as 3 months before conception, the authors suggest preconception should also include any time a woman is at child bearing age. This revision is based on an understanding of the biological events occurring during the periconceptional period, or the time immediately surrounding conception. In addition, it addresses a lack of nutritional preparedness for pregnancy in women of reproductive age and the failure of dietary interventions during pregnancy in preventing adverse health outcomes.
How does pre-pregnancy nutrition affect child health?
The periconceptional period begins before fertilization occurs, with maturation of sperm and oocytes, and extends until implantation of the fertilized egg. From the time of fertilization, this process occurs relatively quickly (up to 9 days in humans) but is characterized by drastic changes developmentally, genetically, and metabolically. The embryonic genome undergoes epigenetic modifications, or alterations to the DNA that do not change the genetic code but rather affect how a gene is expressed by turning expression on or off. These modifications are responsive to environmental conditions and nutrient availability, and likely adapt to promote optimal survival under existing conditions. However, the established gene expression pattern may be detrimental in environmental conditions outside of the uterus, promoting disease development later in life.
Although epigenetic changes can occur throughout one’s lifetime, the periconceptional period is unique in that a small number of cells are present. Full exposure to the environment allows this founder population of cells to establish the genetic program that persists throughout development.
How does this change current practice?
The influence of maternal nutrition during the periconceptional period on disease and development in offspring is not a new concept. Both maternal overnutrition and obesity, as well as undernutrition have been known to adversely affect metabolic regulation in offspring and increase the risk for metabolic disease development.
More recently, analysis from the UK National Diet and Nutrition Survey suggest that less than 10% of women of reproductive age meet the recommended daily intakes during pregnancy for several key micronutrients including zinc, vitamin A, folate, and calcium. Only 30% of women meet the daily intake recommendations for iron. A lack of success of multiple micronutrient supplementation during pregnancy in improving child health outcomes, including survival, growth, body composition, and blood pressure, indicate the importance of correcting such nutritional deficiencies well before pregnancy.
These findings suggest that preconception intervention strategies should include population targeted interventions for women of reproductive age, in addition to those targeting the 3 months before conception. This will allow adequate time to correct for nutritional deficiencies before pregnancy.