Determinants of low birth weight among newborns delivered at Mettu Karl comprehensive specialized hospital, southwest Ethiopia: a case–control study

Low birth weight is a newborn delivered with birth weight of less than 2500 g regardless of gestational age is called. It is a significant issue affecting over 30 million infants worldwide. Thus, the study determine factors associated with low birth weight among newborns delivered at Mettu Karl Comprehensive Specialized Hospital, Southwest Ethiopia. A facility-based case–control study was conducted with 336 newborns (112 cases and 224 controls) from September 12 to December 23, 2022. The study population was newborns with birth weights of 2500 g to 4000 g as controls and newborns with birth weights < 2500 g were cases. Simple random sampling techniques were used to recruit study participants with a ratio of 1 to 3 cases to controls, respectively. Data was collected by interviews and a checklist. Data were entered and analysed using SPSS version 23. Binary and multivariate logistic regression analyses were computed to identify factors associated with low birth weight, a p-value less than 0.05 was used to declare the strength of statistical significance. A total of 327 newborns were contacted, yielding a 97% response rate. MUAC < 23 cm (AOR = 2.72, 95% CI 1.24 to 6.19), inadequate diet diversification (AOR = 4.19, 95% CI 2.04 to 8.60), lack of iron and folic acid supplementation (AOR = 2.94, 95% CI 1.25 to 6.88), history of hypertension (AOR = 2.55, 95% CI 1.09 to 6.00), and lack of nutritional counselling (AOR = 4.63, 95% CI 2.22 to 9.64) were determinants of low birth weight. Low birth weight is linked to residence, maternal MUAC, hypertension history, and ANC visit. Lifestyle modifications, early detection, management, and nutrition information can reduce risk.


Sample size determination
The sample size was determined by using double population proportion formula.By the following assumptions a cases to controls ratio of 1:2.Power = 80%, Zβ = 0.84 for 0.05 significance level, Zα = 1.96OR = Minimal detectable odds ratio is 2, P1 = proportion of exposure among the cases = 40.9%P2 = the proportion exposed in the control = 24.8% 13

Sampling procedures
After additional consideration of the non-response rate of 5%, the total sample size was 336 (112 cases and 224 controls).A simple random sampling techiques were used to select cases.Whereas controls were selected consequatively at the same and same day of delivey with the ratio of 1 to 2 case to controls within 24 h after delivery.Data was collected each time a low birth weight baby had been delivered until the required sample size was attained.

Minimum dietary diversity for women (MDD-W)
The amounts of woman consumes from 10 dietary diversity food groups.

Adequate dietary diversity for women
If women consumed at least five different food groups during the previous day or night, from ten food groups.

Inadequate dietary diversity for women
If women consumed less than five different food groups during the previous day or night, from ten food groups.

Antenatal care (ANC) visits
Which was dichotomized as Yes if a woman has at least one Antenatal care visits and No if a woman has no any Antenatal care visits during the last pregnancy.

Sociodemographic factors
Maternal age, educational status, family income, place of residence, occupation, and family size.

Maternal medical/lifestyle factors
History of chronic diseases like Hypertension, Diabetes Mellitus, Anemia, TB, Malaria, History of Smoking, Chewing chat, and severe physical work during pregnancy.

Data collection tools and management procedures
The data were collected through interviews, structured questionnaires, and medical record reviews.The newborn's weight was measured using a balanced Seca scale (German) to the nearest 0.01 g within 1 h of birth.To assure the quality of data two days of training was given to data collectors and supervisors.Trainings started before actual data collection regarding how to approach the study subjects, how to use questionnaires, the data collection procedures, the context of specific questions, and the anthropometric measurement procedures.Minimum Dietary Diversity for Women (MDD-W) was measured by the ten questions developed by FAO and FANTA as a proxy indicator to reflect the micronutrient adequacy of women's diets.The MDD-W indicator is dichotomous, it returns the value Yes or No.The woman achieves minimum dietary diversity, i.e.Yes, if she consumed at least five different food groups during the previous day or night, and No otherwise (1) Grains, white roots and tubers, and plantains, (2) Pulses (beans, peas and lentils), (3) Nuts and seeds, (4) Milk and milk products, (5) Meat, poultry and fish.(6) Eggs, (7) Dark green leafy vegetables, (8) Other vitamin A-rich fruits and vegetables, (9) Other vegetables, (10) Other fruits 14 .Mid-upper arm circumference (MUAC) was also measured using a non-stretchable MUAC tape according to procedures.The questionaries' was adapted by reviewing different related literature reviews [15][16][17][18][19][20] .

Data processing and analysis
Data were checked for completeness, accuracy, and then cleaned, coded, and were entered to Epi data version 7.0 then exported to SPSS version 23.0 for statistical analysis.Descriptive statistics such as frequency,and percentages were used to describe the study subjects.Binary and multivariate logistic regression analayis was computed to identify factors associated with LBW and a p-value less than 0.05 were used to declare the strength of statistical significances.

Ethical consideration
This research was performed in accordance with the Helsinki Declaration of Principles.A letter of ethical clearance was obtained from the ethics committee of the College of Health Science at Mattu University, with a reference letter of DPH/157/2022.

Consent to participate
All the study participants were informed about the purpose of the study and their right to refuse participation or terminate their involvement during the study.Written informed consent was obtained from each study participant.. Information was provided to each study participant before signing the informed consent form on the purpose of the study, data handling, and confidentiality of the information.

Socio-demographic characteristics of study participants
A total of 327 were contacted (109 cases and 218 controls) agreed to take part in the study, yielding a 97% response rate.Male constituted in the majority 54% and 59.2% of cases and controls respectively in the study.
From the study participants, 35 (32.1%) of the case and 11 (5%) of the control of mothers age were under 20 years (Table 1).

Obstetrics, medical, and nutritional related factors of study participants
In this study, majority of study partcipants 73.3% case and 88.9% control have ANC visits, whereas, 26.7% of cases and 11.1% of controls has no ANC visits.Among study participants 49.5% of cases have no IFA supplementation, whereas 87.6% of controls have IFA supplementation.However only 50.5% of cases have IFA supplementation and 12.4% of control has no IFA supplementation (Table 2).

Logestics regression analysis
A significant association were identified between low birth weight were living the rural area, lack of nutritional counseling History of Hypertension, Having ANC visits, Inadequate minimum MDD-women (Table 3).

Discussion
This study reveals that rural women have a higher odds of having a low birth weight than urban mothers.This agreed with individuals reside influences their behaviours, income, and, most significantly, their health and nutrition 15 .The findings are comparable with studies undertaken in Bale, Oromia, Ethiopia, Malaysia, and Yemen, which found that rural pregnant women are more likely to have low birth weights than urban pregnant women 13,16,17 .However, a study conducted in the Jimma Zone found that women living in urban areas had a higher risk of having low-birth-weight babies 18 .This disparity could be attributed to differences in study design, health awareness, geographical location, and demographic features of study participants.Odds of pregnancy-induced hypertension more risk of developing low birth weight than women who do not have a history of pregnancy-induced hypertension.In fact, high blood pressure may reduce blood flow to the placenta, and as a result, the fetus may not get enough of the nutrients and oxygen needed to grow 15 .Our findings, consistent with studies conducted in north Shewa, Addis Ababa, and Malaysia, showed that pregnant mothers who have a history of pregnancy-induced hypertension were at higher risk of developing low birth weight than pregnant women who have no history of hypertension 9,18,21 respectively.The possible consistency of the finding could be that hypertension in pregnancy causes narrowing placental blood vessels, will be complicated by utero placental insufficiency, and increases the risk of low birth weight outcomes 9 .However, a study conducted in www.nature.com/scientificreports/China showed that hypertensive mothers did not show an increased risk for lowbirth weight 16 .This discrepancy may be due to differences in the study setting, methods, and sociodemographics of the subjects.Additionally, women who were not counselled about nutritional intake during pregnancy had higher odds of having a low birth weight than pregnant women who had been counselled about nutritional intake.Our finding are consistent with a study conducted in North Shewa, Dessie town, Dire Dawa, and Hawassa Ethiopia 10,11,21,22 respectively.The possible consistency of nutritional counselling may improve their intake habits, and having information about eating a healthy diet can reduce the chance of fetal growth restriction and high blood pressure, reducing the risk of low birth weight in pregnant women 15 .
Iron and folic acid supplementation showed significant assocaiation in this study.Pregnant women who do not receive iron and folic acid supplements have a higher odds of developing low birth weight than their counterparts.Our finding agreed with a study in Nekemte town and north Shewa, Ethiopia 21,23 .This is supported by evidence that IFA supplementation protects against low birth weight as a multiple micronutrient supplement 19 .Additionally, having IFA supplementation during pregnancy decreases the odds of developing a low birth weight compared to the uterine parts of pregnant women 9,20,24 .The possible outcomes could be additional intakes of supplementation, reducing morbidities and risks of congenital malformation.
This study discovered that mothers whose MUAC is less than 23 cm have a higher risk of developing a low birth weight than mothers whose MUAC is greater than or equal to 23 cm.This is supported by a study conducted in the Sidama Zone in south Ethiopia, Yemen, and India 3,17,25 respectively.This consistency was supported by the available evidence.Low birth weight is a result of undernutrition and the health status of the mother during her pregnancy; MUAC less than normal affects birth weight outcomes 15 .
Inadequate minimum women's dietary diversification increases the risk of being exposed to low birth weight compared to those who had adequate minimum women's dietary diversification during pregnancy.Our findings aligned with a study conducted in Ghana, systematic review reports where women's dietary diversity scores and dietary patterns were found to be protective against low birth weight 26,27 .This consistency could be due to similarities in background characteristics, study design, and study population.
Lastly, women who have antenatal care are 89 percent more protected from low birth than mothers who had non-ANC visits during their recent pregnancy.This is also consistent with studies in Sidama, Bale, Gondar www.nature.com/scientificreports/Shewa, Ethiopia, and Italy 3,13,28,29 respectively.This could be due to the fact that the World Health Organisation strongly recommends during pregnancy the utilisation of antenatal care used for early identification of risky pregnancy and screening for pregnancy complications, as well as early treatments that improve the birth outcomes of pregnancy.

Strength and limitation of the study
The data was collected with consistent inclusion and exclusion criteria from cases and controls by case control study design to minimise selection bias.Self-reporting methods may lead to recall bias and subjective diagnosis, which may affect the generaliability of findings but not the quality of the study.

Conclusions
Low birth weight was significantly associated with residence, maternal MUAC, non-compliance with IFA supplementation, hypertension history, nutiritonal counselling, minimum MDD-women, and ANC visit of the mother.Life style Modification, early detection, and management of maternal hypertension, as well as strengthening nutrition information and counselling during pregnancy, will help minimise the risk of low birth weight. https://doi.org/10.1038/s41598-024-54248-w

Table 2 .
Obstetrics, medical and nutritional characteristics of study participants in Mettu Karl comprehensive specialized hospital, Southwest Ethiopia.Case (n), number of lowbirth newborn; controls (n), number of normal birthnewborn.