1.1. Background

Micronutrient deficiencies are a key contributing factor to poor health and suboptimal development outcomes, and they especially affect women and children who reside in low- and middle-income countries (LMICs) [1,2]. Micronutrient deficiencies are defined as insufficient amounts of essential vitamins and minerals, which are obtained from the diet, to meet recommended daily allowances for proper health, growth and development [3]. They often result from diets that chronically lack diversity or proper and sufficient nutrients, and in some cases, from infections and/or chronic disease that inhibit proper nutrient absorption [4]. Considered one of the three tenets of the triple burden of malnutrition, also known as hidden hunger, micronutrient deficiencies affect approximately two billion people globally [5,6]. Left unaddressed, micronutrient deficiencies are of particular concern as they will threaten the survival and well-being of women of reproductive age (WRA) and their infants, and may put subsequent generations of children at risk due to the intergenerational transfer of malnutrition [5,7].

Micronutrient deficiencies are often exacerbated during pregnancy due to increased nutritional requirements and, in LMICs, often appear concurrently (deficiencies in two or more micronutrients) [1,8]. Prenatal iron deficiency is one common example with a high global prevalence of 19.2% (95% confidence interval (CI) 17.1-21.5%), while maternal vitamin A deficiency affects approximately 15.3% (95% CI 6.0-24.6%) of pregnant women [1]. Despite sparse population-level data on deficiencies, these estimates reflect the current state of health of the global maternal population. Repeated pregnancies and short inter-pregnancy levels are also known contributors to poor maternal micronutrient status [2].

Micronutrients are critical for optimal pregnancy outcomes and proper metabolic activities that support tissue growth and functioning in the developing fetus. As such, deficiencies result in a vast array of adverse health outcomes affecting both mother and baby. Anemia, commonly caused by iron deficiency, is associated with increased risks of maternal mortality, perinatal mortality and low birthweight [9,10,11]. Folate and iodine deficiencies are well known to severely impair fetal development, leading to neural tube defects (NTDs) and an increased risk of mental retardation and cretinism, respectively [12,13]. Insufficient calcium during pregnancy is linked to the development of hypertension, which is a leading cause of maternal mortality, morbidity, fetal growth restriction and preterm birth [14,15]. Similar to calcium, vitamin D deficiency can lead to pre-eclampsia, and subsequently increase the risks of preterm birth, small-for-gestational age (SGA) and perinatal mortality [16,17,18]. While the effects of maternal zinc deficiency are not well established, it has been suggested that maternal zinc supplementation can reduce preterm birth [19].

Maternal malnutrition not only negatively affects the mother and fetus during the period of pregnancy, but also manifests through intergenerational effects. It can significantly alter the short-term and long-term health and development outcomes in offspring, including growth, neurodevelopment and cognition, and cardio-metabolic, pulmonary and immune functions [20]. Poor nutritional status in mothers shortchanges a newborn’s chance to reach their fullest potential in growth and development in the short term and establishes a trajectory for chronic illness and other diseases in adolescence and adulthood. Poor fetal and infant health due to maternal malnutrition are associated with stunting that can be sustained into adulthood, chronic diseases relating to nutrition, lower educational attainment, reduced income, and even decreased birthweight in the subsequent generation [21].