Inadequacy of nutrients intake among pregnant women in the Deep South of Thailand

A hospital-based cross-sectional survey was approved by the Ethics Committee of the Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand (reference no. EC 50/354-012), the Ethics Committee of the Ministry of Public Health (reference no. 9/2008) and the Chief Medical Officers of Narathiwat Provincial Health Offices and the Directors of participating hospitals. All eligible pregnant women were invited to join the study. Written informed consent was obtained from all recruited subjects.

Narathiwat province was purposively selected to be the study setting because the prevalence of maternal anemia and low birth weight are high. In addition, the people living in this area are culturally different from those of people in other regions of the country. Hospitals from four districts, namely Ra-Ngae, Tak Bai, Su-Ngai Padi and Cho-Irong were chosen as the study hospitals. All pregnant women with a gestational age of 12 to 20 weeks, who had lived in Narathiwat province for at least one year prior to the study and had attended their first antenatal visit in one of the study hospitals during January-December 2008, were included in the study. High-risk pregnancies such as severe anemia of less than seven gm/dl, heart disease, AIDS, or any mental problems were criteria for exclusion.

The prevalence of inadequacy of nutrient intake in a previous study varied considerably [10], so the average prevalence (55%) was considered in this study. In order to estimate this prevalence with 95% confidence and a precision of 5%, a total of 380 pregnant women were needed.

A one-day training workshop was arranged by the investigators to allow the relevant staff of each participating hospital to be acquainted with the study details and data collection procedures. One full-time female research assistant was employed at each hospital to collect the data under regular supervision of the first author.

After receiving a full explanation on the purpose of the study, the women were given a self-administered structured questionnaire to ascertain their individual baseline characteristics. The table of food intake recommended for pregnant women published in an antenatal care handbook provided by the Ministry of Public Health, Thailand was used for guidance of food items required. The six food groups including rice, vegetable, meat, fruit, fat and milk were listed. The units for measuring the amount of each food was recorded as ladles for rice and vegetables, portions for fruit, tablespoons for meat, tea-spoons for fat and glasses for milk. Photographs of the types and amounts of foods were shown to the women to improve estimation of portion size. The subjects were requested to recall their average daily intake for breakfast, lunch, dinner and supper over the previous two weeks for all food groups and the amount eaten using the standard units mentioned above. If the consumed food was not in the list, then that kind of food was converted into an equivalent amount of the same food type. For example, noodles were converted into rice equivalent. Total food intake regarding types, amount and frequency were calculated into weight of macronutrient and micronutrient using the modified Food Nutrient Conversion Table endorsed by the Nutrition Division of the Ministry of Public Health, Thailand [17].

The two main outcome variables were level of macronutrients, which included carbohydrate, protein, fat and calories, and level of micronutrients, which included minerals (calcium, phosphorus and iron), vitamins (thiamine, riboflavin, retinol, niacin, vitamin c, folic acid) and iodine. Inadequacy of macronutrients and micronutrients was defined as having total nutrient intake lower than two-thirds of the RDA.

Individual characteristics obtained from each subject were age, religion, gestational age, occupation, education level, family income, number of family members, pre-pregnancy weight, height and number of live children. Community characteristics in 2008 on population density, average household income and literacy rate were obtained, while number of violent events, number of deaths and number of injuries in 2008 were retrieved from the Violence-related Injury Surveillance database [18]. The level of violence in study communities was determined by a weighted violence score which was retrieved from three parameters of violence, namely the number of violent events, number of injuries and number of deaths from violent events. These three parameters were divided by the mid-interval population to obtain the standardized scores of numbers of events, injured cases and dead cases, respectively. Factor analysis was then run on these three violence-related variables to obtain a weighted violence score for each district, reflecting the level of violence. Women living in the same district thus had the same weighted violence score.

The data were computerized using Epidata 3.1 and analyzed using R software version 2.9.1 (The R Foundation for Statistical Computing 2008, Austria). The total daily intake of macronutrients and micronutrients was described using means and quartiles. Percentage of RDA (the actual quantities of nutrients divided by the RDA levels multiplied by 100) and percentage of inadequacy were computed. Logistic regression models using backward stepwise selection were fit to the data to estimate the effect of individual and community level factors on nutrient intake. The results were shown as odds ratios with 95% confidence intervals (95% CI). Statistical significance was considered for p values less than 0.05.

Table 1 shows the community characteristics in each study district in 2008. Ra-Ngae had the highest population while Chi-Irong had the highest population density. Ra-Ngae district had the highest average household income and violence rate compared to the other districts. The districts with a high violence rate (per 100,000 population) also had high injury and death rates. The most common violent events were bomb blasts and shootings.

Of 462 eligible women approached, 400 (86.5%) consented to participate in the study. Individual characteristics of these participants are presented in Table 2. Approximately one-third of participants were aged between 25 and 29 years. Half of them were housewives and had completed secondary school. The majority were Muslim and were in poor economic status with monthly income lower than 156 USD. Underweight (BMI <18.5 kg/m²) was detected in 16.8% of the participants.

Table 3 describes nutrient intake among the participants compared to the Thai RDA. Carbohydrate, protein, fat, calories, calcium, phosphorus, iron, thiamine, riboflavin, retinol, niacin, vitamin C, folic acid and iodine inadequacy was 86.8%, 59.2%, 78.0%, 83.5%, 55.0%, 29.5%, 45.2%, 85.0%, 19.2%, 3.8%, 43.2%, 0.8%, 0.0% and 0.8% respectively. The RDAs for all measured macronutrients, minerals and thiamine were in the fourth quartile of participant's nutrient intakes. The RDAs for retinol, vitamin C, folic acid and iodine were in the first quartile. If two-thirds of the RDA is considered as inadequate, the prevalence of inadequate macronutrient intake was over 59%.

Due to the low prevalence of folic acid, vitamin C, iodine, retinol and riboflavin intake inadequacy in our sample demonstrated, these variables were excluded from the analysis of micronutrients. Tables 4 and 5 present the final model of logistic regression predicting inadequacy of macronutrients and micronutrients, respectively. Maternal age, educational level, gestational age at enrolment, pre-pregnancy BMI and level of violence were associated with nutrient inadequacies.

Women aged less than 20 years were at a lowest risk of macronutrient and micronutrient inadequacy compared to those aged 20-34 years. Women with a primary school education were at a high risk for inadequacy of most nutrients. Gestational age was consistently associated with most nutrient inadequacies. If gestational age was more than 14 weeks, the risk of having macronutrient and micronutrient inadequacy was lower. Pre-pregnancy BMI was associated with only carbohydrate inadequacy. Women with low pre-pregnancy BMI had a lower risk of inadequacy compared to those with normal BMI. Level of violence, represented by weighted violence score in the area, was associated with a high risk of inadequacy for most macronutrients and micronutrients.