INTRODUCTION

Anemia in pregnant women, considered as a blood hemoglobin (Hb) concentration lower than 110 g / l, is one of the most important public health problems¹. The World Health Organization (WHO) reports that 56,4 million pregnant women have anemia worldwide². The highest prevalence of this pathology occurred in Africa and Southeast Asia, that is, in developing countries³. The prevalence of anemia in pregnant women in 2016 in Latin America and the Caribbean was 29,5%⁴and in Peru it was 25,8%⁵. With respect to the provinces of Peru, Huancavelica and Puno registered 45,5% and 42,8% respectively⁵.

During pregnancy, anemia has a significant impact on both the health of the fetus and the mother. Consequently, premature rupture of membranes, premature birth, oligohydramnios, susceptibility to develop infections, hemorrhages, etc⁶,⁷. As for the newborn, it conditions the appearance of cardiovascular diseases in his adult life⁸, In addition, an anemic pregnant woman who presents with obstetric hemorrhage and puerperal infection has a higher probability of death in relation to those who do not present this pathology⁹,¹⁰.

Taking into account that anemia in pregnant women can be prevented, there are certain factors that constitute this pathology. Among them are not attending regularly or going too late to their prenatal check-ups¹¹,¹²; have lower levels of education¹⁰,¹¹,¹³, which lead to ignorance of care before and during pregnancy¹²; being a primiparous mother¹¹,¹⁴and being in the second trimester of pregnancy¹⁵,¹⁶.

In consideration of the above, anemia in pregnant women is one of the causes of maternal-fetal death¹⁷so it is important to know the factors to prevent it. For this reason, the objective of this study was to determine the relationship of sociodemographic, obstetric and prenatal factors to anemia in pregnant women according to the Encuesta Demográfica y de Salud Familiar (ENDES) 2017.

METHOD

Study of quantitative, non-experimental and analytical approach. A secondary analysis of the database of the Encuesta Demográfica y de Salud Familiar 2017 (ENDES 2017) was carried out. The ENDES was done by the Instituto Nacional de Estadística e Informática (INEI)¹¹to obtain data that may have a national representativeness. The sample design was two-stage through conglomerates and homes.

The effective sample consisted of 639 women between 15 - 49 years. Only women who are between the first to the ninth month of their pregnancy and who have been able to answer the obstetric and prenatal questions were included.

The main variable was anemia, defined as the concentration of hemoglobin less than 11 g / dl in pregnant women¹⁸. It was categorized into iron-deficiency anemia (less than 11 g / dl) and did not present anemia (greater than or equal to 11 g / dl). For the measurement of this variable, the Hemocue® instrument (an instantaneous and reliable photometric method) was used as well as being adjusted by the subject's altitude applying the formula ofPediatric Nutrition Surveillance System(CDC / PNSS) andDirren¹⁹.

For the measurement of sociodemographic variables, age in years, quantitative variable; natural region, (metropolitan Lima, rest of coast, mountain and jungle); educational level, qualitative polytomous variable (without education, primary, secondary and higher); residence, dichotomous qualitative variable (urban and rural); quintile of wealth defined in relation to wealth in the households surveyed, was taken into account. Instead of income, the wealth quintile depends on the availability of goods and services as well as the characteristics of the dwellings. It is an ordinal qualitative variable (upper quintile, fourth quintile, quintile intermediate, second quintile and lower quintile)²⁰and marital status: single, married, cohabiting and others. Regarding the obstetric and prenatal variables were: number of children, quantitative variable; gestational age, qualitative polytomous variable (first trimester, second trimester and third trimester); beginning of prenatal control, qualitative polytomous variable (1st month, 2nd month, third month to more) and number of controls, quantitative variable.

For the statistical analysis of the study, the statistical package Stata version 14 was used. Descriptive statistical analysis was performed obtaining frequency and percentages for the qualitative variables and averages and standard deviation for the quantitative variables. In the inferential analysis we used the normality and variance test of the quantitative variables to be able to use the correct statistical analysis when they intersect with other variables. TheStudent's Ttest and the Chi-square statistical test were performed. In the unadjusted bivariate analysis, Poisson regression was used with the robust variance estimate, calculating the crude prevalence ratio (PR)²¹and 95% confidence intervals. All these analyzes had a statistical significance less than 0,05. Regarding the ethical aspects, ENDES is a public access database in which women were surveyed with verbal consent.

RESULTS

Of the total of 639 pregnant women, the average age was 27 years, 49,1% had a secondary education level, 31,9% belonged to a lower quintile and 67,4% were cohabiting. In addition, of the total number of respondents, the mean number of children was 2,11, 40,4% started their control after the third month, 44,9% were found in the second trimester of pregnancy, 76,3% had anemia and 23,6 did not present the same (see Table 1).

Table 1. Description of the sample 

Note: Standard deviation (SD).

In Table 2, both in the descriptive bivariate analysis and the unadjusted (crude) model, the sociodemographic factor associated with anemia was the educational level (p = 0,041). That is, pregnant women with a higher educational level are less likely to have anemia compared to those without education (PR: 0,91, 95% CI: 0,42-1,96). On the other hand, having fewer children (p = 0,02), starting prenatal control in the third month (p = 0,03) and being in the second trimester of pregnancy (p = 0,04) were associated with the presence of anemia. The rest of the associations were not significant, Regarding the analysis of the unadjusted (crude) model, the obstetric and prenatal factors associated with anemia were: the number of children (0,016), the start of prenatal control (p = 0,047) and gestational age (p = 0,024), Pregnant women with more children are less likely to have anemia compared to those with fewer children (PR: 0,87, 95% CI (0,42-1,96). On the other hand, pregnant women who initiate their control as of third month they have 1,48 times more chance of presenting anemia than those who started their control in the first month (PR: 1,4, 95% CI: 0,74-1,58). The second trimester of pregnancy is 1,35 times more likely to have anemia than those found in the first trimester (PR: 1,35, 95% CI: 0,74-1,58).

Table 2. Bivariate analysis between sociodemographic, obstetric and prenatal factors associated with anemia in Peruvian pregnant women, ENDES 2017 

^*From the Student's T test

^†PR: Prevalence ratio, IC: Confidence interval. The calculations were made with the "Yes" category of the dependent variable.

DISCUSSION

In this study of the total of pregnant women, 23,6% presented anemia. In addition, the sociodemographic protective factor associated with anemia was the higher educational level. Regarding the obstetric-prenatal factors associated with anemia, the beginning of prenatal control was started from the third month and the second trimester of pregnancy. A protective factor was having more children.

In the present study it was evidenced that pregnant women with a higher educational level have less possibility of presenting anemia compared to those without education. Studies reported that low educational level and awareness of anemia also contributed to the increase of this pathology in pregnant women¹⁰,¹³. Women with a lack of education are generally of low socioeconomic class, therefore they do not have access to good maternal health services. Therefore, they are more prone to poor nutrition and other infections during pregnancy¹⁰. It should be noted that pregnant women who presented anemia before pregnancy, a condition that had to be treated previously, brings a series of complications both for the health of the fetus and the mother and even the death of both¹⁰, due to lack of knowledge in preparing to have a future baby. Studies report that the key to reducing the prevalence of anemia is the educational and economic empowerment of women¹³,²².

Another finding of the study was that pregnant women with more children have fewer times of presenting anemia compared to those with fewer children. Studies reported that primiparous women had anemia compared to multiparous women¹⁴,²³. Although anemia in pregnancy is often related to the increase in parity due to repeated drainage of iron stores²². It usually happens that in primiparous women due to lack of knowledge, lack of prenatal care and not preparing for the birth of their baby (with the iron and folic acid supplement before getting pregnant) they have anemia and they get worse with the advance of the months of pregnancy²²,²³. Given the above, the socio - demographic profile of pregnant women in the study, most have a lower quintile and low educational levels, therefore pregnant women who have fewer children have not become aware of the importance of nutrition during pregnancy²⁴and do not know that the healthy diet in relation to daily requirements is three main meals plus an additional ration and consume supplements that provide vitamins and minerals orally⁷,²⁵.

In the same way, pregnant women who are in the second trimester of pregnancy presented anemia, Studies report that anemia occurs in pregnant women as pregnancy progresses¹⁰,¹⁵. Another study showed that in the second trimester of pregnancy (week sixteen) the hemoglobin levels were lower than 10,5 g / dl¹⁶, since in this trimester of pregnancy the level of hemogline is decreased due to hemodilution by the increase in plasma volume by 45% to 50% for the needs of the uterus and growing fetus; an underlying maternal infection and untreated anemia in the first trimester of pregnancy.

Significantly, most pregnant women in the study began prenatal care after the third month, this is similar to reports from other studies¹⁴,¹⁵where the prevalence of anemia was 4,08% in the first weeks of gestation and it increased as the pregnancy progressed to 16,32%¹⁵. Finally, in the United Arab Emirates, it was found that pregnant women who had fewer prenatal controls increased the risk of anemia¹⁴. In the prenatal controls, relevant information is extracted from the mother and from them nutritional counseling is provided, including vitamin and mineral supplements such as folic acid and iron, The growth and optimal development of the embryo or fetus is also controlled²⁵. That is why, if the pregnant woman initiates her controls early and continues with the counseling in each trimester, she will reduce the risk of anemia and its complications⁷.

CONCLUSIONS

In this study, 23,6% of pregnant women have anemia. Higher educational level and having more children are protective factors of anemia in pregnant women. The start of prenatal control from the third month and the second trimester of pregnancy was associated with the presence of anemia in pregnant women.