This study evaluated the prevalence of gestational nightblindness among postpartum women seen at the University Maternal Hospital of the Federal University in Rio de Janeiro, Brazil and the association of this symptom with a biochemical indicator (serum retinol levels) and sociodemographic, anthropometric and antenatal care variables. In total, 262 postpartum women, who did not receive vitamin A supplementation during pregnancy, were interviewed. Gestational nightblindness was diagnosed through the standardized interview as proposed by WHO. Serum retinol levels were evaluated by spectrophotometry. Gestational nightblindness relating to low levels of serum retinol (<1.05 µmol/L, p=0.000) was diagnosed in 17.9% of subjects interviewed. Less than five antenatal care appointments (odds ratio [OR]=2.179; confidence interval [CI] 95%=1.078-4.402) and a history of one or more miscarriage(s) (OR=2.306; CI 95%=1.185-4.491) were predictors for gestational nightblindness. These findings justify the need for nutritional counselling, aimed at improving the vitamin A nutritional status, especially among pregnant women with a history of previous miscarriages and poor antenatal care.
Key words: Nightblindness; Pregnancy; Prenatal care; Abortion; Vitamin A deficiency; Vitamin A; Brazil
The impact of vitamin A deficiency on reproductive health, in terms of its repercussions on maternal and infant health, has been well-documented (1-5). Identification of women at risk of vitamin A deficiency during pregnancy allows for intervention, aimed at improving maternal hepatic vitamin A reserves and preventing insufficient placental transfer to the foetus, as observed in cases of severe maternal deficiency (6,7). The measures currently recommended for the prevention and treatment of gestational vitamin A deficiency and nightblindness are based on supplementation, food enrichment with vitamin A, and alimentary diversification (4,8,9), always considering the ingestion amount safe for each biological moment (10).
To meet the expectations of international health committees and the scientific community, several lessinvasive, low-cost indicators have been tested and validated for diagnosing vitamin Adeficiency, which is still a public-health problem in various parts of the world (4,5,8).
Evaluation of nightblindness through a standardized interview has been widely employed by researchers in population-based studies, through a low-cost, simple, culturally-accepted methodology, allowing for the detection of high rates of prevalence of maternal and infant vitamin A deficiency (1-3,11,12).
During the 1930s, Ricketts reported two cases of pregnant women with vitamin A deficiency in the USA, presenting nightblindness associated with vomiting, headache, and anaemia (13). In the 1960s, Dixit reported 38.9% of pregnant women with nightblindness in India, principally in the third trimester, with remission of ocular symptoms during the postpartum period (14). In both the studies, supplementation of vitamin A during pregnancy was followed by remission of symptoms and nightblindness.
Gestational nightblindness was formerly attributed to physiological adjustments in pregnancy (14), but recent studies conducted in Asia have described the association between this ocular symptom and a fivefold risk of maternal mortality during two years postpartum compared to women without gestational nightblindness (2). Increased mortality among infants during the first six months of life also appears to be associated with gestational nightblindness (3). In addition, pregnant women with nightblindness and vitamin Adeficiency appear to be more predisposed to complications during pregnancy, such as spontaneous abortion, urinary, genital and gastrointestinal infections, pregnancy- induced hypertension, other digestive signs and symptoms, and decreased appetite (1,15,16). Hence, gestational nightblindness was recently suggested as a marker for high-risk gestations (17). …