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| ORIGINAL ARTICLE |
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| Year : 2023 | Volume
: 22
| Issue : 3 | Page : 271-278 |
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Determinants and outcomes of low birth weight among newborns at a tertiary hospital in Zambia: A retrospective cohort study
Moses Mukosha1, Choolwe Jacobs2, Patrick Kaonga3, Patrick Musonda2, Bellington Vwalika4, Mwansa Ketty Lubeya4, Chiluba Mwila5, Steward Mudenda5, Ellah Zingani5, Kunda Mutesu Kapembwa6
1 Department of Pharmacy, School of Health Sciences, University of Zambia; Department of Epidemiology and Biostatistics, School of Public Health, University of Zambia; Lusaka Zambia, HIV and Women's Health Research Group, University Teaching Hospital, Lusaka, Zambia
2 Department of Epidemiology and Biostatistics, School of Public Health, University of Zambia, Lusaka, Zambia
3 Department of Epidemiology and Biostatistics, School of Public Health, University of Zambia; Department of Internal Medicine, School of Medicine, Tropical Gastroenterology and Nutrition Group, University of Zambia, Lusaka, Zambia
4 Lusaka Zambia, HIV and Women's Health Research Group, University Teaching Hospital; Department of Obstetrics and Gynecology, School of Medicine, University of Zambia, Lusaka, Zambia
5 Department of Pharmacy, School of Health Sciences, University of Zambia, Lusaka, Zambia
6 Department of Neonatology, Women and Newborn Hospital, Lusaka, Zambia
| Date of Submission | 27-Jan-2022 |
| Date of Decision | 17-Mar-2022 |
| Date of Acceptance | 07-Jan-2023 |
| Date of Web Publication | 4-Jul-2023 |
Correspondence Address:
Moses Mukosha
Department of Pharmacy, School of Health Sciences, University of Zambia, Lusaka
Zambia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/aam.aam_22_22
 Abstract | | |
Context: Newborns' low birth weight (LBW) has been linked to early infant morbidity and mortality. However, our understanding of the determinants and outcomes of LBW in this population is still poor. Aim: This study aimed to assess determinants and outcomes of LBW among newborns at a tertiary hospital. Settings and Design: Retrospective cohort study at Women and Newborn Hospital in Lusaka Zambia. Subjects and Methods: We reviewed delivery case records and neonatal files between January 1, 2018, and September 30, 2019, for newborns admitted to the neonatal intensive care unit. Statistical Analysis Used: Logistic regression models were used to establish determinants of LBW and describe the outcomes. Results: Women living with human immunodeficiency virus infection were more likely to deliver LBW infants (adjusted odds ratio [AOR] = 1.46; 95% confidence interval [CI]: 1.16–1.86). Other maternal determinants of LBW were; increased parity (AOR = 1.22; 95% CI: 1.05–1.43), preeclampsia (AOR = 6.91; 95% CI: 1.48–32.36), and gestational age <37 weeks compared to 37 weeks or more (AOR = 24.83; 95% CI: 13.27–46.44). LBW neonates were at higher odds of early mortality (AOR = 2.16; 95% CI: 1.85–2.52), developing respiratory distress syndrome (AOR = 2.96; 95% CI: 2.53–3.47), and necrotizing enterocolitis (AOR = 1.66; 95% CI: 1.16–2.38) than neonates with a birth weight of 2500 g or more. Conclusions: These findings underscore the importance of effective maternal and neonatal interventions to reduce the risk of morbidity and mortality for neonates with LBW in Zambia and other similar settings.
Résumé
Contexte: Le faible poids de naissance des nouveau-nés (LBW) a été lié à la morbidité et à la mortalité précoces du nourrisson. Cependant, notre compréhension des déterminants et des résultats de LBW dans cette population est encore médiocre. Objectif: Cette étude visait à évaluer les déterminants et les résultats de LBW chez les nouveau-nés dans un hôpital tertiaire. Paramètres et conception: Étude de cohorte rétrospective à l'hôpital des femmes et du nouveau-né à Lusaka Zambia. Sujets et méthodes: Nous avons examiné les dossiers de cas de livraison et les dossiers néonatals entre le 1er janvier 2018 et le 30 septembre 2019 pour les nouveau-nés admis à l'unité de soins intensifs néonatals. Analyse statistique utilisée: des modèles de régression logistique ont été utilisés pour établir des déterminants de LBW et décrire les résultats. Résultats: Les femmes vivant avec une infection par le virus de l'immunodéficience humaine étaient plus susceptibles de livrer des nourrissons LBW (rapport de cotes ajustée [AOR] = 1,46; intervalle de confiance à 95% [IC]: 1,16–1,86). Les autres déterminants maternels de LBW étaient; Parité accrue (AOR = 1,22; IC à 95%: 1,05–1,43), prééclampsie (AOR = 6,91; IC à 95%: 1,48–32,36) et âge gestationnel <37 semaines par rapport à 37 semaines ou plus (AOR = 24,83; 95% IC: 13.27–46.44). Les nouveau-nés LBW étaient à des chances de mortalité précoce plus élevés (AOR = 2,16; IC à 95%: 1,85–2,52), développant un syndrome de détresse respiratoire (AOR = 2,96; IC à 95%: 2,53–3,47) et en entérocolite nécrotitaire (AOR = 1,66; 95 % IC: 1,16–2,38) que les nouveau-nés avec un poids de naissance de 2500 g ou plus. Conclusions: Ces résultats soulignent l'importance des interventions maternelles et néonatales efficaces pour réduire le risque de morbidité et de mortalité pour les nouveau-nés avec LBW en Zambie et d'autres contextes similaires.
Mots-clés: Déterminants, infection par le virus de l'immunodéficience humaine, faible poids à la naissance, nouveau-nés
Keywords: Determinants, human immunodeficiency virus infection, low birth weight, neonates
How to cite this article:
Mukosha M, Jacobs C, Kaonga P, Musonda P, Vwalika B, Lubeya MK, Mwila C, Mudenda S, Zingani E, Kapembwa KM. Determinants and outcomes of low birth weight among newborns at a tertiary hospital in Zambia: A retrospective cohort study. Ann Afr Med 2023;22:271-8 |
How to cite this URL:
Mukosha M, Jacobs C, Kaonga P, Musonda P, Vwalika B, Lubeya MK, Mwila C, Mudenda S, Zingani E, Kapembwa KM. Determinants and outcomes of low birth weight among newborns at a tertiary hospital in Zambia: A retrospective cohort study. Ann Afr Med [serial online] 2023 [cited 2023 Sep 26];22:271-8. Available from: https://www.annalsafrmed.org/text.asp?2023/22/3/271/380151 |
| Introduction | |  |
Low birth weight (LBW) is mainly defined as weight at birth <2500 g.[1] LBW is of public health concern and is widely accepted as the most critical determinant of future chances of healthy growth, infant survival, and illnesses later in life.[2] Globally, LBW is estimated between 15% and 20% of all births translating to more than 20 million births per year, which meet LBW criteria.[1] Sub-Saharan Africa (15%) and South-central Asia (27%) regions share a disproportionate burden of LBW.[2],[3] For example, in Zambia, Chibwesha et al.[4] reported that about 11% of newborns in Lusaka were LBW.
According to the WHO guidelines, pregnant women living with human immunodeficiency virus (HIV) are put on antiretroviral therapy (ART) option B plus in Zambia.[5] This has seen a rapidly increasing number of HIV-exposed uninfected infants. HIV is considered to be responsible for various placental pathologies which are linked to LBW.[6] Prominent among the theories is through the pro-inflammatory process induced by high levels of interleukin-2 (IL-2), IL-6, and tumor necrosis factor-alpha due to HIV infection.[7] Before introducing ART for the treatment of HIV, studies reported the link between HIV and LBW.[8],[9] However, after the initiation of widespread ART, the effects of HIV infection on birth weight became more challenging to assess partly due to the differences in the timing of ART initiation, type of ART, and adherence challenges.
Several studies have shown that maternal determinants of LBW are multifactorial.[10],[11],[12],[13],[14],[15],[16] The extant literature has reported LBW determinants: HIV-seropositivity, preeclampsia, preterm birth, primiparity, high gravidity, employment, poor maternal nutrition, and young maternal age.[17],[18],[19] In a study done in South Africa of 2529 singleton live-born babies, the odds of LBW among HIV-infected pregnant women were 1.45-fold compared to HIV-negative pregnant women. In Nairobi, HIV-positive women were 3-fold more likely to deliver a LBW baby than HIV-negative women.[20] Similarly, birth weight was significantly lower in women with HIV infection in Rwanda and Ethiopia than in uninfected women.[21],[22]
LBW is a significant risk factor for neonates' adverse health outcomes, including necrotising enterocolitis, early mortality, respiratory distress syndrome, and retinopathy of prematurity.[23],[24] The risk of adverse neonatal outcomes is higher among HIV-exposed newborns.[9],[25] Rollins et al.'s study in South Africa found that LBW substantially increased early mortality among neonates. Other reported complications are neurological impairments, metabolic syndrome, and cardiovascular disease among LBW infants in later life.[26],[27]
The WHO has set a target for member countries to reduce LBW rates by 30% by 2025.[1] This ambitious target will require considerable effort, particularly in low-middle-income countries with a high burden of LBW.[28] In its policy brief, the WHO mentioned that neonatal morbidity and mortality reduction would only be attained if pregnancy care is fully integrated with appropriate neonatal and postneonatal nutritional and medical care. Implementing evidence-informed interventions to tackle LBW will be more effective and have a greater impact on health equity if the implementation is fuelled by collaboration among programs and sectors. Women living with HIV have been identified to be at the highest risk for LBW delivery.[11] Therefore, there is an urgent need to understand the determinants of LBW in Zambia and other sub-Saharan African settings in the context of high HIV prevalence.
The present study had two objectives. The first was to assess maternal socio-demographic, clinical, and obstetric factors associated with LBW among newborns admitted to the neonatal intensive care unit (NICU). The second was to estimate the odds of adverse neonatal outcomes within 28 days of admission to NICU among LBW neonates compared to neonates weighing more than 2500 g.
Understanding the determinants of LBW and neonatal outcomes is essential to provide information to health workers on the risk level stratification and target and evaluate interventions. Furthermore, this study's findings will assist in assessing national targets to achieve the global goals and tracking the progress toward them as we fast approach 2025.
| Subjects and Methods | | |
Study design and setting
This was a retrospective cohort study at the Women and Newborn Hospital. This is the largest referral hospital for obstetric, gynecological and critically ill neonates requiring specialist care.[29] On average, about 28,800 admissions of pregnant women and 9000 births per year are recorded at this hospital. The average neonatal admissions per year are above 4000.[30] The hospital receives referrals from over 20 health centers and five first-level hospitals from within Lusaka and other parts of the country.[31] In addition, the hospital is a training site for future specialist gynaecologists, obstetricians, and undergraduate medical and nursing students of the University of Zambia School of Medicine. The Department of Obstetrics conducts outpatient antenatal clinics where HIV-infected women are identified, investigated, and commenced on ART according to the WHO option B plus.
Study population and sampling technique
The study population comprised newborns (HIV exposed and nonexposed) admitted to NICU at Women and Newborn Hospital between January 1, 2018, and September 30, 2019. We classified HIV exposed as neonates born from HIV-infected women (in the study setting, confirmatory polymerase chain reaction test results are routinely done at 18 months from birth). The neonatal files were reviewed with a follow-up period of 28 days from admission to determine any adverse outcomes within 28 days. We conducted a complete enumeration of eligible delivery case records and neonatal files. Details of the data extraction procedure have been previously described.[31] Briefly, files for each month under the study period were collected from the registry office and screened for the primary outcome of interest (record of birth weight at delivery). Eligible files were further screened for a record of adverse neonatal outcomes at day 28 of admission. After screening the files, the de facto eligible sample came to 3213 records [Figure 1]. | Figure 1: The sampling frame for the records. BW, NICU. BW = Birth weight, NICU = Neonatal intensive care unit
Click here to view |
Data extraction
The study extracted data from the delivery case records and neonatal files. We used a predesigned excel-based sheet for data entry and audited all the information every day to ensure its completeness and accuracy. All the relevant demographic, obstetric, clinical, and neonatal data were extracted from delivery case records and neonatal files. The variables comprised antenatal care (ANC) attendance, maternal age, maternal HIV status, gravidity, parity, gestational age at delivery, history of preterm birth, sex of baby, preeclampsia, substance use, respiratory distress syndrome, necrotizing enterocolitis, mortality within 28 days and admission to Kangaroo Mother Care (KMC). First, we entered the data into the Microsoft excel operating system version 16 (2016 Jones, Chicago, USA). Then, we carried out data cleaning, coding, and validation until the database corresponded with the forms' data collected. After that, data was exported to Stata/IC version 16.1 (Stata Corporation, College Station, Texas, USA) for analysis.
Study measures
We assessed the outcome measures for the study at two-time points (admission and on day 28). For objective 1, the outcome was LBW (categorized as 1, if weight <2500 g and 0 = if weight ≥2500 g) recorded at admission to NICU. On the other hand, in objective 2, we quantified the odds of adverse perinatal outcomes in LBW neonates compared with neonates weighing more than 2500 g for three adverse neonatal outcomes: respiratory distress syndrome (yes = 1, no = 0), necrotizing enterocolitis (yes = 1, no = 0), and early neonatal mortality (yes = 1, no = 0) within the 1st 28 days of life. The diagnosis of necrotising enterocolitis in this setting is mainly clinical and/or suspected, and if not taken to the theater, the neonatologists do not confirm the diagnosis as there is no portable X-ray available in the department. Conversely, respiratory distress syndrome is a clinical diagnosis. It is diagnosed based on signs of respiratory distress in a newborn with risk factors.
Statistical analysis
We conducted a descriptive analysis of socio-demographic, obstetric, clinical, and neonatal characteristics. For the descriptive analysis, age, parity, and gravidity were categorized. We expressed all categorical variables as frequencies and percentages. We used the Pearson Chi-square test (expected cell frequency more than five) as appropriate to assess for associations between variables.
For the primary outcome, we first conducted a univariable logistic regression with socio-demographic, obstetric, and clinical characteristics to obtain crude estimates (outcome LBW: yes = 1 and no = 0). We then fitted a multivariable logistic regression model including only variables with a P < 0.20 from the univariable analysis to adjust for confounders in three parts. First, we explored the effect of only HIV-serostatus on LBW to obtain unadjusted estimates. We took the analysis with only HIV as unadjusted because HIV status variable was a priori variable. Second, we analyzed the data by adding employment status, gestational age, parity, and preeclampsia to obtain adjusted estimates. Third, stratified data with HIV-negative and HIV-positive separately. Finally, we compared LBW infants to those weighing 2500 g or more for our secondary analyses. We estimated crude and adjusted odds ratios for the neonatal outcomes; (viz., respiratory distress syndrome, necrotizing enterocolitis, and mortality within 28 days). Three separate analyses were fitted for secondary outcomes similar to the primary analysis. The analysis fitted used stepwise regression after biologically and clinically considering the appropriate explanatory variables to be investigated in the stepwise regression with a liberal P value for exclusion (P < 0.1). Only the HIV-serostatus was fixed in the adjusted models as it was set as priori. Then, a stratified logistic regression model by HIV-serostatus was fitted, similar to the overall model (secondary outcomes).
We considered age, parity, and gravidity as continuous variables for the regression models (primary and secondary outcomes). Interactions among variables were investigated, and none were found to approach any statistical significance. We used Hosmer–Lemeshow goodness-of-fit test to assess the fit of the model. A P < 0.05 was considered statistically significant for this analysis. Stata/IC version 16.1 (Stata Corp., College Station, Texas, USA) was used for statistical analysis.
Ethical considerations
Ethics approval was obtained from the University of Zambia. In addition, we obtained additional permission from Women and Newborn Hospital management. However, medical records from maternal delivery notes and neonatal files were de-identified, and no direct contact with participants was made to protect the participant's confidentiality; therefore, no informed consent was obtained.
| Results | | |
Study characteristics
[Table 1] shows the maternal and newborn study characteristics. Of the 3213 pregnant women, 638 (19.8%) were HIV seropositive. The majority were; aged between 20 and 29 years 1484 (49.4%), low multiparity 2132 (72.0%), pregnant more than twice before 1311 (43.6%), unemployed 2392 (93.3%), attended ANC 3152 (98.0%), and gave birth to preterm infants 2250 (70.0%). Among the newborn infants from the 3213 pregnant women, 162 (5.0%) developed necrotising enterocolitis, 1482 (46.1%) developed respiratory distress syndrome, 1111 (34.6%) were admitted to KMC, 1775 (55.3%) were male, and 1947 (60.6%) died within 28 days from birth.
There was an association between birthweight and the following: HIV-serostatus (P = 0.002), necrotizing enterocolitis (P = 0.040), gestational age (P < 0.001), preeclampsia (P < 0.001), admission to KMC (P < 0.001), respiratory distress syndrome (P < 0.001), and sex of newborn (P < 0.001). Overall, the magnitude of LBW among infants admitted to NICU was 1935/3213 (60.2% 95% confidence interval: 58.51–61.92, using Binomial exact methods).
The results from a multivariable analysis on maternal factors associated with low birthweight are shown in [Table 2]. In the unadjusted Model 1, HIV infection was associated with 33% increased odds of a LBW infant. After adjusting for employment status, gestational age, preeclampsia and parity, the effect of HIV infection increased to 46% in the overall adjusted Model 2. In stratified analysis, factors associated with LBW among HIV infected women were gestational age, parity, and preeclampsia. Compared to infants born at or after 37 weeks of gestation, infants born <37 completed weeks of gestation had 24-fold increased odds of LBW. The odds of LBW were 6.91 times higher among infants born from mothers who developed preeclampsia during pregnancy than those who did not. A unit increase in parity was associated with a 22% increase in odds of LBW. Similar trends were observed among the HIV negative women for gestational age and preeclampsia. Being in employment compared to unemployment among HIV-negative women was associated with reduced odds of LBW by 35%. | Table 2: Multivariable logistic regression model of maternal factors associated with low birthweightc
Click here to view |
Results of the adverse neonatal outcomes are shown in [Table 3]. After adjusting for the risk factors (preeclampsia, employment status, parity, and gestational age) of LBW identified in [Table 2], there was an increased odds of necrotising enterocolitis, respiratory distress syndrome, and mortality within 28 days among LBW neonates compared to those weighing ≥2500 g (Model 1). The effect of LBW on mortality and respiratory distress syndrome was consistent when stratified by HIV serostatus except for necrotising enterocolitis, which showed a negative association for the HIV exposed neonates (Model 3).
| Discussion | | |
This study assessed the determinants of LBW and adverse neonatal outcomes among HIV-exposed and nonexposed newborn infants admitted to NICU. We found that six in every ten neonates admitted to NICU had a LBW compared to four in every ten neonates weighing 2500 g or more. Maternal determinants of LBW among the newborns were: HIV seropositive, increased parity, preeclampsia, and gestational age <37 weeks. In addition, neonates with LBW were at higher odds of early mortality, developing respiratory distress syndrome, and necrotizing enterocolitis when compared to neonates with a birth weight of 2500 g or more.
In the present analysis, clinical and obstetric determinants of LBW, including HIV-seropositivity, preeclampsia, employment, preterm birth, and increased parity, are consistent with the extant literature.[4],[8],[32] A study done in Tanzania showed that, HIV-positive women were twice as likely to deliver LBW infants than HIV-negative women.[8] This was supported by the findings in Ethiopia,[33] Malawi,[25] Botswana,[34] and South Africa.[9] A plausible reason for the observed association could be that HIV infection creates increased nutritional requirements.[35],[36] Nutritional status, including micronutrients, has prognostic implications in people with HIV/AIDS.[37],[38] Zambia, a LMIC, is likely to have women unable to meet the nutritional demands of pregnancy due to HIV infection and chronically poor diet.[39] Speculations that this could be linked to the high magnitude of LBW might potentially be exacerbated by the burden of HIV infection and ART use.
Another reason could be that HIV-infection may alter the cytokine profile in the placenta.[40],[41] This may affect the function of the placenta during pregnancy, thereby restricting the development of the fetus, which might be another incentive of LBW. Moreover, HIV infection and ART has been linked to overexpression of the Type 1 T helper, which are thought to be accountable for adverse pregnancy outcomes.[42] All pregnant women who are HIV positive in our study setting receive ART as a routine standard of care. However, the present study was not able to assess time on ART and the type of regimen as these were not documented in delivery case records. Furthermore, adherence data were not recorded, although a pilot study in a similar setting showed 96% adherence levels among pregnant women.[43]
Consistent with the extant literature,[4],[33] preeclampsia and gestational age <37 have previously been linked to LBW among HIV-positive pregnant women. For example, a study in Ethiopia reported higher odds of LBW infants among women who developed preeclampsia and delivered preterm.[33] The link is thought to be through endothelial dysfunction, leading to disorders of placental development and systemic vasospasm and subsequent fetal growth restriction.[44] Recently, Ross et al.[45] studied women who delivered preterm and LBW infants and found that those who developed preeclampsia had different metabolic markers. The findings are suggestive of biological plausibility for preeclampsia to be a precursor to LBW and preterm birth.
Moreover, our study revealed a positive association between gestational age <37 weeks and LBW, with the likelihood of being a LBW infant increasing among newborns with gestational age <37 weeks. These findings were corroborated by other studies conducted in Zambia,[4] Tanzania,[46] Ethiopia,[47] Kenya,[29] and India.[45] This is plausible because gestational age below 37 weeks happens before the completion of intrauterine growth, and this is when the preferred birth weight has not been reached, leading to LBW.[45]
In the present study, LBW was associated with increased odds of developing respiratory distress syndrome, necrotising enterocolitis, and early mortality (within 28 days from birth), and this was consistent with published literature.[4],[48] LBW's effect on the development of respiratory distress syndrome can be explained by the possibility that a more considerable proportion of such infants are small for gestational age.[48] When an infant is small for gestational age, the lungs are structurally immature and prone to surfactant deficiency, which is needed to lower surface tension and prevent alveolar collapse.[49]
LBW of neonates has been linked to early infant mortality previously.[28] Therefore, it was not surprising to find that most LBW infants were more likely to be admitted to KMC. The WHO recently recommended KMC to be the standard of care for LBW infants after evidence showed that it reduced mortality rates among LBW neonates and is now the standard of care in Zambia.[50] KMC has been reported to be an effective way to reduce neonatal mortality due to continuous skin-to-skin contact between mother and baby, which improves baby's temperature, supports exclusive breastfeeding, and helps early recognition/response illness.[45]
Strengths of the study
Our study has some strengths, including using a large data set for analysis compared to similar studies. Moreover, we conducted this study in the context of high HIV prevalence. Furthermore, LBW is of public health concern and is widely accepted as the most critical determinant of future chances of healthy growth and infant survival, particularly in a lower-middle income country like Zambia.
Study limitations
Our study had some limitations. First, we were unable to assess time on ART since all HIV infected pregnant women were on ART. Second, we were not able to adjust for some maternal variables: diabetes, maternal nutritional status, CD4 count, viral load, intracranial haemorrhage, patent ductus arteriosus, place of delivery, type of pregnancy (multiple or singleton gestation), maternal nutritional status, body mass index, and maternal smoking status as these were not recorded in case record files which could influence our outcomes. Third, gestational age may not have been collected with sufficient precision since mothers are only asked at ANC visit during registration, leading to bias in classification. In addition, antenatal dating scans are not commonly done at the study setting as this would help in accurate gestational age measurement if done around 18–22 weeks. Furthermore, necrotizing enterocolitis could not be confirmed by X-ray and therefore, the results on this variable should be interpreted with caution.
| Conclusions | | |
Overall, 60.2% of the newborns admitted to NICU at Women, and Newborn Hospital met the criteria for LBW, and these newborns were at markedly increased risk for adverse outcomes, including early neonatal death, necrotizing enterocolitis and respiratory distress syndrome. Preeclampsia, HIV-seropositive, increased parity, and gestational age <37 increased the risk of LBW substantially. These results underline a need for comprehensive, early, and high-quality prenatal and ANC. In addition, they highlight the importance of effective maternal and neonatal interventions to reduce the risk of morbidity and mortality for neonates with LBW in Zambia and other similar settings.
Acknowledgments
We would like to thank the staff members at Women and Newborn Hospital for their assistance in retrieving files from the records office. Special thanks also go to the management of Women and Newborn Hospital for permitting us to use their data. Moses Mukosha and Mwansa Ketty Lubeya would like to acknowledge that some of their time is supported by the UNC-UNZA-Wits Partnership for HIV and Women's Reproductive Health (grant number: D43 TW010558).
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1]
[Table 1], [Table 2], [Table 3]
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