Introduction: low birth weight is one of the most important health problems worldwide and nationally. Objective: determine the risk factors associated with low birth weight in pregnant women at the Pedro Borrás Astorga Polyclinic in Pinar del Río during the year 2023. Methods: observational, descriptive and cross-sectional research, with a universe of 943 pregnant women from this polyclinic and a sample of 22 of them who had low birth weight during the period in which the study was carried out were randomly selected, respecting the inclusion and exclusion criteria. The medical records of the pregnant women were reviewed obtaining the variables: maternal age, smoking habit, interpregnancy period, gestational age and diseases associated with pregnancy. Descriptive statistics were used and established ethical standards were taken into account. Results: pregnant women over 35 and under 19 years of age predominated (40.9%); A high frequency of smoking was found (36.3%). 36.3% of women had an intergenic period of less than two years and 54.5% of births occurred between 37 and 41.6 weeks. The predominant pregnancy-associated condition was vaginal infection (45.4%). Conclusions: age over 35 years and under 19 years, smoking, short birth period, multiparous mothers and vaginal infection were the main risk factors associated with low birth weight in pregnant women at the Pedro Borrás Polyclinic. Astorga de Pinar del Río during the year 2023.
Gestational Age, Maternal Age, Risk Factors, Pregnant women, Mothers, Birth Weight.
The causes of low birth weight are due to alterations in the mother, the placenta, or the fetus, but whatever the cause, in many cases it is unknown; however, it is currently considered to be the result of multifactorial causes. [1]
Low birth weight (LBW) is defined as a birth weight of less than 2500 grams, regardless of gestational age or cause, and is the most important predictor of infant mortality, especially neonatal mortality. An estimated 15% to 20% of all children born worldwide are LBW. The goal for 2025 is to reduce the number of children weighing less than 2500 grams by 30%. ( 2)
Adequate birth weight is synonymous with health and well-being, and is also linked to the socioeconomic status of the population. Low birth weight has been a scientific enigma throughout history. Epidemiological studies of low birth weight frequently encounter a disproportionate number of factors studied and the limited results of the study of these factors, in addition to the inadequacy of epidemiological analysis. [3]
Various maternal conditions, both prior to and during pregnancy, are most frequently referred to in the medical literature as risk factors for LBW, including: teenage pregnancy, maternal malnutrition (weight less than 100 pounds, height less than 150 cm, low weight for height, and insufficient weight gain during pregnancy), smoking, history of low-weight children, induced abortion (curettage), high blood pressure during pregnancy, isthmic-cervical incompetence, twin pregnancies, anemia, cervico-vaginal sepsis, among others. [4]
One in six children is born with low birth weight, with developing countries accounting for the largest number at 17% and least developed countries at 18%. Of the estimated 20 million or more low birth weight births each year in the developing world today, more than half occur in South Asia and more than a third in Africa. [5]
In contrast, LBW in industrialized countries averages 7%, the same as in East Asia and the Pacific. The lowest incidence (4%) is found in Estonia, Finland, Iceland, Lithuania, and Sweden. India accounts for approximately 40% of all low birth weight births in the developing world. Fourteen percent of infants in sub-Saharan Africa and 15% of those in the Middle East and North Africa are also born with low birth weight. In the United States, approximately one in 12 babies is born with low birth weight. [6]
In Cuba, the LBW rate has been increasing during the years 2020, 2021, and 2022: 5.6%; 6.6%, and 7.2%, respectively. In Pinar del Río province, satisfactory results have been obtained in recent years in reducing infant mortality; in 2022, it was the province with the best infant mortality rate in the country with 3.2 per thousand live births; however, the LBW rate maintains levels very similar to the LBW rates in the country; in 2022, it was 6.7% despite the actions carried out by the health system in the province. [7]
The importance of the phenomenon and its behavior in the health area present in the study has served as a stimulus to carry out this research, which aims to determine the risk factors associated with LBW in pregnant women at the Pedro Borr á s Astorga Polyclinic in Pinar del Río during the year 2023.
An observational, descriptive and cross-sectional study was carried out with a universe of 943 pregnant women from this polyclinic and a sample of 22 of them who had low birth weight during the period in which the study was carried out. They were randomly selected and the inclusion and exclusion criteria were respected.
Pregnant women who provided LBW during 2023 and who agreed to be included in the research.
Patients who were outside their area of residence at the time of the investigation or who left the area before the investigation concluded.
were reviewed , as well as the medical records of pregnant women. The following variables were obtained: maternal age, smoking habits, interpregnancy period, gestational age at birth, and pregnancy-associated diseases.
Once the information was obtained, the variables were quantified, and the relationship between them was measured using the EpiInfo 6 statistical program, which calculated the percentage as a summary measure for qualitative variables. The results were presented in tables.
The cross-product ratio (Odds Radio) was applied as an epidemiological instrument to have a measure that quantifies the strength of association between the risk factor and the event, and to confirm the association the Chi-square test was applied, with 95% reliability and a significant value for a probability (p) less than 0.05 and highly significant for a (p) less than 0.01.
The principles of medical ethics and the international recommendations of the Declaration of Helsinki were followed . The study was approved by the Ethics Committee of the Pedro Borrás Astorga Polyclinic in Pinar del Río and the University of Medical Sciences of Pinar del Río.
There were statistically significant differences in the distribution of maternal age, with a significant difference for mothers over 35 years of age and those under 19 years of age, with nine mothers respectively ( TABLE 1 ).
| Maternal age | Patients | |
|---|---|---|
| No | % | |
| Under 19 years old | 9* | 40.9 |
| From 20 to 34 years old | 4 | 18.1 |
| More than 35 years | 9* | 40.9 |
| Total | 22 | 100 |
2=2.33 *P<0.05 OR= 0.31
Eight of the women studied were found to be smokers, with a significant incidence (p < 0.05) and an OR of 5.14, demonstrating that this habit is an important risk factor for low birth weight. ( TABLE 2 )
| Smoking Habit | Patients | |
|---|---|---|
| No | % | |
| Smokes | 8 | 36.3 |
| Does not smoke | 14 | 64.2 |
| Total | 22 | 100 |
p<0.05 OR=5.14
Of the total sample studied, eight of the women who gave birth to a low-birth-weight infant had a short interbirth period of less than two years, making the difference found in this regard highly significant. The OR was 2.51, demonstrating the strong association between the occurrence of LBW and this risk factor. ( TABLE 3 )
| Intergenetic period | Patients | |
|---|---|---|
| No | % | |
| Under 2 years old | 8 | 36.3 |
| 2 years or more | 14 | 41.5 |
| Total | 22 | 100 |
OR=2.51 p<0.05
In this study, when applying statistical analysis according to the number of births, it is shown that there is a significant difference in the cases of multiparous mothers [10] who predominated in the contribution of low birth weight newborns, followed in order of frequency by nulliparous mothers [9] ; it is evident that there is 2.9 times the possibility of low birth weight in those multiparous mothers. ( TABLE 4 )
| Parity | Patients No % |
|
|---|---|---|
| 0 | 9* | 40.9 |
| 1 | 1 | 4.5 |
| 2 | 2 | 9.09 |
| 3 or more | 10** | 45.4 |
| Total | 22 | 100 |
*p<0.01 OR=4.05
The most common pregnancy-associated conditions were vaginal infection in 10 pregnant women, pregnancy-induced hypertension in six patients, and bronchial asthma and urinary tract infections in two patients, respectively, for an OR of 1.20. ( TABLE 5 )
| Diseases associated with pregnancy | Patients | |
|---|---|---|
| No | % | |
| Pregnancy-induced hypertension | 6 | 27.2 |
| Vaginal Infection | 10 | 45.4 |
| Bronchial asthma | 2 | 9.0 |
| Urinary infection | 2 | 9.0 |
| Anemia | 1 | 4.5 |
| Others | 1 | 4.5 |
| No diseases | 22 | 35.8 |
P<0.05 OR=1.20
The consulted medical literature refers that health risks increase when the mother is a teenager or over 35 years old, because biopsychosocial conditions have a greater impact and there is a higher incidence of gestosis, obstetric interventions and effects on the weight of the newborn, [8] which coincides with the results of this research in which the majority of pregnant women are under 19 and over 35 years old.
Very similar to these results were obtained by Placeres Lozada et al. [9] in a study conducted in the special municipality of Isla de la Juventud, in which the predominant age of mothers at the appearance of low birth weight newborns was less than 18 years. It has been demonstrated that after 35 years of age, biological elements begin to appear that denote biological wear and tear such as the decompensation of chronic diseases such as high blood pressure and diabetes mellitus, although from the psychological, emotional and economic point of view these topics are more solid; which coincides above all with the Latin American panorama reflected in works.
Fernández-Brizuela et al. [10] reflect in studies carried out that as maternal age increases (more than 35 years of age), newborns tend to have an increasingly lower weight, a phenomenon that is attributed to the age of the pregnant woman together with parity.
Guerra et al. [11] suggest that there is a close link between smoking habits and the weight of the newborn; they consider that the weight of children of smoking mothers is on average 200-300 grams less than the weight of children of non-smoking mothers and that those who quit smoking on the eve of pregnancy had children born with less weight (on average 70-170 grams).
Other authors [12] have stated that the habit of smoking causes the secretion of oxytocin which triggers preterm labor.
Smoking is a risk factor for chronic degenerative and neoplastic diseases, but it is also very harmful to obstetric conditions, with disastrous consequences, which is perfectly explained by the harmful effects of nicotine on the body. It has been proven that smoking reduces the weight of the future newborn due to the hypoxia caused by the free penetration of carbon monoxide through the placenta. [13]
The authors of this research agree with the cited articles that smoking is a risk factor associated with low birth weight, as demonstrated in this study. They also believe that primary health care providers play an important role in community health education. Therefore, they should influence pregnant women to quit smoking. A person's beliefs about healthy behaviors are very important; therefore, it is essential to provide the necessary information to correct misconceptions.
When births occur at very short intervals, the mother does not have the necessary time for biological recovery and as a consequence, the newborns have low birth weight. [14] This research demonstrated a strong association between the presentation of LBW and the short interbirth period.
It has been established that the length of the interbirth period is directly related to social conditions and access to information and services that, if appropriate, facilitate the correct choice of the most favorable time for conception. If the interbirth period is short (less than 2 years), maternal nutrient reserves may be scarce, and the supply of these nutrients to the fetus during pregnancy may be affected, which could lead to the appearance of a low birth weight newborn. [15]
Fernández Sopeña et al. [16] found that the interval between pregnancies influences LBW rates. When this interval is greater than 23 months, the incidence of low birth weight is 7.8%, but when the interval is less than 12 months it is 18%.
The authors believe that it is important for physicians and nurses working in primary health care to keep in mind the relationship between LBW and the short interpregnancy period, in order to provide adequate follow-up and monitoring of women with this associated factor. Therefore, it is essential to plan not only the number of children but also the spacing between pregnancies.
Monzón Tamargo et al. [17] suggest that the presence of children with low birth weight was higher in children of mothers who have given birth, corresponding to the present study.
Regarding the presence of pregnancy-associated diseases, Reboiras et al. [18] have shown that these conditions are a determining factor in the genesis of LBW. Although in this study vaginal infection and pregnancy-induced hypertension were the diseases with the highest incidence, there are researchers such as Martínez-Torres [19] who found anemia and gestational diabetes to be more frequent.
Similar results to those obtained in this research were obtained by Llerena Gómez and Ezcurdia Barzaga, [20] in which vaginal infection and hypertension were the most frequent diseases in mothers who had LBW, followed by urinary tract infections and bronchial asthma.
These results highlight the importance of taking action for women in the preconception period, as measures can be taken before pregnancy and achieve positive results.
This research identified the risk factors associated with low birth weight as a health problem in a health area and provided primary health care teams with scientific support, the necessary elements to design and implement actions aimed at addressing this problem and achieving a positive impact on reducing the rate of low birth weight and the associated morbidity and mortality.
Age over 35 and under 19, smoking, short interbirth period, multiparous mothers, and vaginal infection were the main risk factors associated with low birth weight in pregnant women at the Pedro Borr á s Astorga Polyclinic in Pinar del Río during 2023.
GAHH: Conceptualization, investigation, methodology, formal analysis, project administration, writing of the original draft, writing, review and editing.
ZGG: Conceptualization, methodology, supervision, writing, review and editing.
LLA: supervision, writing, review and editing.
The authors declare that there are no conflicts of interest.
The authors did not receive funding for the development of this article.
Copyright 2024 Guillermo Alejandro Herrera Horta et al.
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