Vitamin A Deficiency Among Pregnant Women
English: % of women who suffered from night blindness during last pregnancy
French: % de femmes ayant souffert de cécité nocturne au cours de leur dernière grossesse
Portuguese: % de mulheres que sofreram de cegueira nocturna durante a última gravidez
Czech: % žen, které byly během posledního těhotenství postiženy noční slepotou
What is its purpose?
The indicator measures the proportion of women who experienced night blindness during their last pregnancy, a condition in which a person cannot see in dim light. Night blindness is the earliest and easiest-to-measure manifestation of vitamin A deficiency.
How to Collect and Analyse the Required Data
Collect the following data by conducting individual interviews with a representative sample of women of reproductive age:
RECOMMENDED SURVEY QUESTIONS (Q) AND POSSIBLE ANSWERS (A)
Q1: When did you deliver your youngest child?
A1: less than 3 years ago / more than 3 years ago
(ask the next question only if she delivered less than 3 years ago)
Q2: During your last pregnancy, did you have any problem seeing in the daytime?
A2: yes / no / does not remember
(ask the next question only if the previous answer is NO)
Q3: During your last pregnancy, did you have any problem seeing in the evening or at nighttime?
A3: yes / no / does not remember
(ask the next question only if the previous answer is YES)
Q4: Did you have night blindness? (use local term that describes the symptom)
A4: yes / no / does not remember
To calculate the indicator’s value, divide the number of women (who delivered a live baby in the past 3 years) who experienced night blindness by the total number of interviewed women (exclude all who replied “does not remember”). Multiply the result by 100 to convert it to a percentage.
Disaggregate the data by wealth.
1) Do not collect the data from pregnant women (night blindness usually occurs during the later part of pregnancy, so measuring during pregnancy will likely underestimate the prevalence).
2) Whenever possible, find and use a local name for night blindness.
3) According to WHO, the prevalence of night blindness among pregnant women is considered as a severe public health problem if ≥ 5% of women in a population have a history of night blindness in their most recent pregnancy which end in a live birth in the previous 3 years.
4) Since the prevalence of night blindness is relatively low, the margin of error must be very low (preferably 0.5); otherwise, it is unlikely that you will be able to objectively assess the impact of your intervention. This requires using a very large sample of women (ranging from 8,000 to 30,000 women) and makes assessing vitamin A deficiency quite demanding.
5) Consult and ideally co-implement the survey with the relevant health authorities, so that you increase the chances of the results being officially recognized (and ideally also acted upon).
6) Since assessing vitamin A deficiency is quite demanding, before you conduct a new survey, first review the availability of existing data – you might be able to use it as your baseline (however, ensure that you will later be able to gain comparable endline data).
Access Additional Guidance
- WHO (2014) Assessment of Vitamin A Deficiency (.pdf)
- WHO (2012) Assessing Vitamin A Deficiency (.pdf)
- The Journal of Nutrition (2002) Recommendations for Indicators: Night Blindness during Pregnancy (.pdf)