Maternal nutrition and the outcome of pregnancy - A renaissance in research

These are exciting times for researchers, clinicians, and students interested in the effects of maternal nutrition on pregnancy outcome. A renaissance in maternal nutrition research is underway, and it promises to replace much of the controversy that surrounds this topic with insight. The new era of research is characterized by a paradigm shift in reasoning about how nutritional exposures may affect fetal growth, development, and the long-term health of individuals. It assumes that relationships between maternal nutritional exposure and outcomes may be nonlinear, that birth weight may be a relatively insensitive measure of nutritional effects, that the nature and extent of health problems related to nutrition depend on the timing and severity of maternal nutritional insults during pregnancy, and that mildly deficient as well as excessive levels of nutrients can impair fetal growth and development, and perhaps lifelong health. In recent years, a new appreciation for the complexity of nutrition research in pregnancy has become evident. Maternal nutrition research is progressing beyond the point where one or two indicators of nutritional status such as maternal weight gain or iron status, are used to form conclusions regarding the totality of the effects of ''maternal nutrition'' on pregnancy outcome. Maternal nutrition is a broad area of investigation encompassing the study of the effects of energy (kcal), 40-plus essential nutrients, and hundreds of biologically active but nonessential components of food such as caffeine, alcohol, flavonoids, phytates, and phytoestrogens on the course and outcome of pregnancy. It includes the study of the effects on outcomes of maternal body composition, weight, energy and nutrient need, availability, metabolism, utilization, and changes in these variables across pregnancy. Because nutrition exposures usually act in tandem with other factors that may influence pregnancy course and outcome, the study of maternal nutrition often must Include consideration of the effects of preexisting confounders and effect modifiers, such as genetic make-up, parity, smoking, illness, physical activity, drug and medication use, and interactions among nutrients, As the new era of research is demonstrating, the relationship of maternal nutrition to pregnancy outcomes is not as simple as it has been assumed to be historically, There is no single indicator of the effect of maternal nutrition on the outcomes of pregnancy but rather there are multiple effects of various nutrients and other nutritional exposures. as knowledge accumulates, it is becoming clear that the use of birthweight as the primary outcome used to assess maternal nutrition effects map be less informative than outcomes such as proportionate size at birth, congenital anomalies, development of physiologic systems, and chronic disease and disorder risk later in life. Recent results strongly suggest that maternal nutrition should be of concern not only for populations living in poverty and abject circumstances but should be considered a factor that may affect outcomes of all pregnancies. Results of increasingly sophisticated research employed in the last 10 years are having a profound effect on the direction of research in maternal nutrition, and are calling into question previous results that govern the application of knowledge in practice. Results emerging from the renaissance in research indicate that nutritional exposures may be of more importance to pregnancy outcome and subsequent health than had been imagined previously. This article highlights these recent developments, summarizes current nutrition recommendations for practice, and is an overview of the accumulating body of evidence that implicates aspects of maternal nutrition in the development of hypertension, heart disease, diabetes, and other disorders in offspring.