Vitamin A is a fat-soluble micronutrient vital for maternal and fetal well-being. It exists primarily as preformed retinol in animal products and as provitamin A carotenoids, such as beta-carotene, in plant foods. During pregnancy and lactation, the maternal requirement for vitamin A increases significantly to support fetal tissue growth, cellular differentiation, and the maintenance of maternal visual and immune systems.
Key physiological functions include:
In Nigeria, dietary intake of vitamin A heavily relies on both local agricultural staples and public health fortification programs. Preformed vitamin A is found in liver, eggs, and whole milk, while provitamin A carotenoids are abundant in dark green leafy vegetables like fluted pumpkin leaves (ugu) and bitter leaf, as well as orange-fleshed sweet potatoes and red palm oil.
Because vitamin A is fat-soluble, its absorption in the small intestine requires dietary fats and functioning bile salts. In many communities, diets low in dietary fats can impair the uptake of carotenoids from plant sources, even when vegetable consumption is adequate.
Vitamin A deficiency progresses through distinct clinical stages, severely affecting ocular health. The earliest symptom is night blindness (nyctalopia), where the eyes fail to adapt adequately to dim light, a condition frequently reported by pregnant women in rural settings.
As the deficiency worsens, it advances to xerophthalmia, characterized by drying of the conjunctiva and cornea. Clinical signs include:
Beyond vision, vitamin A plays an indispensable role in immunological competence. It maintains the integrity of mucosal linings in the respiratory, gastrointestinal, and genitourinary tracts, forming a primary physical barrier against invading pathogens.
When vitamin A stores are depleted, epithelial barriers flatten and lose their protective mucus secretion, allowing bacteria and viruses to invade more easily. In children, this immunological failure dramatically increases the severity and mortality rates of common childhood infections like measles and severe diarrheal disease. In mothers, deficiency contributes to increased postpartum morbidity and higher risks of infectious complications.
Identifying vitamin A deficiency in clinical and community settings relies on a combination of dietary histories, clinical signs, and biochemical evaluations. Midwives should actively screen pregnant and lactating women by asking targeted questions about visual changes at dusk or night.
Physical examinations focus on inspecting the eyes for signs of xerosis or Bitot's spots. While serum retinol laboratory testing provides definitive confirmation of subclinical deficiency, it is expensive and logistically difficult in routine primary healthcare centers across Nigeria. Therefore, clinical observation and dietary screening remain the practical frontline tools.
Public health strategies to combat vitamin A deficiency focus on a multi-pronged approach: dietary diversification, food fortification, and high-dose vitamin A supplementation. Pregnant and postpartum women, as well as children under five, are primary targets.
Midwives play a crucial role in educating communities on consuming locally available vitamin A-rich foods and ensuring adherence to national supplementation guidelines. Foods like vegetable oils and wheat flour are routinely fortified at the industrial level. However, caution must be exercised during pregnancy: high-dose therapeutic supplements must be managed carefully, as excessive preformed retinol intake can be teratogenic to the developing fetus.