Pregnant environments. The mismatch will increase the risk
Pregnant women need to consume appropriate amounts of nutrition, including proteins, carbohydrates, fats, and micro-nutrients for fetal growth. In recent years, some researchers reported that the amount and type of required nutrition depends on the individual. For example, pregnant teenagers need more nutrition than adult women, especially calcium intake, because they are not fully developed. They still need nutrition to grow as well as needing to consume enough nutrition for the fetus. Vegetarians need to consume additional micro-nutrients to compensate for nutrients that are not in their food, especially vitamin B12, riboflavin, calcium, iron and zinc (Williamson 2006). During pregnancy, both malnutrition and over-nutrition will cause health problems in adult life. Enough nutrition intake is very important for pregnant women. Malnutrition during pregnancy will have negative effects on fetuses and infants. For example, according to fetal programming hypothesis, when there is not enough nutrition fetuses would use the energy for brain growth instead of viscera growth, decrease insulin and insulin-like growth factor-1 (IGF-1) secretion and sensitivity, increase the number of insulin receptors and glucose absorption, and up-regulate the hypothalamo-pituitary-adrenal (HPA) axis in order to adapt to malnutrition (Fall 2009, Calkins and Devaskar 2011). These changes will cause “programming changes,” within endocrine system and abdominal organs structure and or function changes. The mechanism of these changes is associated with epigenetic DNA modifications, principally DNA methylation which can control gene expression (Brenseke et al. 2013, Wood-Bradley et al. 2013, Le et al. 2009, Chmurzynska et al. 2012). According to the “mismatch” hypothesis, babies with “programming changes” need to live in similar nutritional environments, otherwise their abdominal organs and changed endocrine system can not adapt to new environments. The mismatch will increase the risk of chronic diseases in adulthood, including cardiovascular disease, hypertension, glucose intolerance and insulin resistance (Brenseke et al. 2013, Le et al. 2009). Researchers also reported that malnutrition during pregnancy affects babies’ weight (birthweight<2.5kg), including intrauterine growth restriction (IUGR), small for gestation age (SGA) and very low birthweight (VLBW) (birthweight <1.5kg) (Williamson 2006). Particularly, low birthweight will increase the risk of some diseases. For example, fetuses with asymmetric intrauterine growth restriction induces underdeveloped organs and underweight placenta. The underweight placenta induces a raised amount of fetal hematocrit. An increase in hematocrit causes fetal coronary circulation lesion which is associated with coronary heart disease (Le et al. 2009). Typically, these infants would have "catch-up" growth after they are born which means they will gain more fat for viscera growth by being fed with extra-nutritional diets. This mismatch then will induce metabolic syndromes, insulin resistance, and factors of cardiovascular disease development, including type 2 diabetes and hypertension (Williamson 2006, Le et al. 2009). Researchers reported that cardiovascular disease may be passed to the offspring (Calkins and Devaskar 2011). Some studies showed that fetuses that are small for gestation age had a decreased amount of antioxidant substrates (glutathione, albumin and many micro-nutrients) as well as antioxidant enzyme activity, such as superoxide dismutase and catalase. Pancreatic beta cells are more susceptible to increased oxidative stress, which causes reduction in insulin secretion, metabolic syndromes, and other related diseases (Brenseke et al. 2013). Rodriguez and his team (2017), showed that male offspring who are malnourished during the fetal period are more susceptible to oxidative stress when compared to female offspring. If fetuses were exposed to many stress factors, female infants do not have hypertension. That is why females have less cardiac damage than male infants in early age. However, all offspring (both males and females) lose left ventricular function and have left ventricular hypertrophy when they age. However, the effects of the sex-limited mechanism on heart disease and hypertension during pregnancy malnutrition is still unclear (Rodríguez-Rodríguez et al. 2017). Some studies illustrated that infants with very low birthweight (<1.5kg) would have psychiatric disorder which has differences for sexuality. For example, male infants with VLBW increase the risk of attention deficit and hyperactivity disorder (ADHD) in adult life, while females usually feel anxious and depressed. However, the mechanism is unknown (Calkins and Devaskar 2011). Brenaeke and his colleagues (2013), reported that if malnutrition occurred in the late period of pregnancy, it increases the secretion of glucocorticoids. Excessive glucocorticoids will change the activity of the hypothalamic-pituitary-adrenal (HPA) axis in adult life. This might be the cause of low birthweight induced metabolic syndromes (Brenaeke et al. 2013). Thus, avoiding malnutrition during pregnancy is crucial to infants' immediate health and their health in adult life.