NIGHT BLINDNESS OF PREGNANCY IN RURAL NEPAL - NUTRITIONAL AND HEALTH RISKS

Background Night blindness (XN) is the most common clinical symptom of vitamin A deficiency among children in developing countries. Yet litt le is known about the aetiology or associated risks of maternal XN. Em erging evidence from South East Asia suggests that it may be more freq uent than previously thought in women of reproductive age, especially during pregnancy. Methods A population-based, case-control study was c onducted to reveal the epidemiology of XN among pregnant Nepali women. Night blind cases were identified by history through a weekly communi ty surveillance system. Controls were randomly selected from a pool of pregnant women without XN and pair-matched for gestational age of the cases. A home-based assessment was done within a week of selection, a t which 7-day food frequency and morbidity histories were collected, a nthropometry measured, and capillary blood drawn for serum retinol, be ta-carotene and haemoglobin (Hb) estimation. Results Cases and control s did not differ by age or number of previous pregnancies. How ever, c ases were more likely to be from the lower castes, be illiterate, live in poorer quality homes, and own no land. The mean serum retinol leve l of cases was similar to 0.30 mu mol/l lower than controls (P < 0.001 ), indicating a low vitamin A status of night blind pregnant women. Me an Hb level was significantly lower (by 0.7 g/dl, P < 0.004), and the risk of severe anaemia (Hb <7.0 g/dl) higher among cases than controls (odds ratio = 3.0, 95% CI: 1.25-7.23). Cases were more undernourished than controls reflected by lower mean weight (-2.6 kg), body mass ind ex (-0.8), arm circumference (-0.9 cm) and triceps skinfold (-0.8 mm). Night blindness was associated with less frequent consumption of pref ormed vitamin A (milk products, fish and meat) and provitamin A (dark green leafy vegetables and mangoes) foods, especially in summer. Night blind women were 2-3 times more likely to report symptoms of urinary/ reproductive tract infections such as lower abdominal pain, painful an d burning urination, or vaginal discharge, symptoms of diarrhoea/dysen tery, of pre-eclampsia or eclampsia, and of nausea, vomiting or poor a ppetite throughout pregnancy than controls. Conclusion Women who exper ience XN during pregnancy have a low vitamin A status, although severa l other risk factors appear to cluster among these women as well. Nigh t blind women are also more likely to be anaemic, ill, and acutely und ernourished, and to be consuming a nutritionally poorer diet in pregna ncy than non-night blind pregnant women. A simple history of XN can id entify women at high risk during pregnancy who may require special nut ritional support, antenatal care and counselling.