Study area, design and period
The research was conducted in randomly selected three government hospitals in Addis Ababa, Ethiopia, namely, Gandhi Memorial Hospital, Yekatit 12 Medical College Hospital, and Zewuditu Memorial Hospital. The determining factors of low birth weight among term babies born in government hospitals in Addis Ababa city were studied using a hospital-based unmatched case control study design. The study was carried out between June and September in the year 2020 G.C.
All randomly selected term babies (37 to 42 weeks) are delivered at three government hospitals in Addis Ababa. The cases were taken from neonates delivered in three government hospitals with a birth weight of less than or equal to 2,499 gm, while the controls were taken from those born with normal birth weight (2,500 gm to 4,200 gm). The eligibility criteria for participants were All birth cards (mother and neonate cards) with Low birth weight (less than or equal to 2,499 gm) or normal birth weight (2,500gm to 4,200), Live birth, singleton term baby and Gestational age between 37 to 42weeks. We exclude those mothers who had any chronic medical complications , eclampsia or pre-eclampsia, and babies with congenital abnormalities.
The sample size (number of the cases) for the present study was determined using unmatched case control formula .With the assumption of double population proportions formula. ANC visit, maternal weight during pregnancy, and gravida are considered. However, maternal weight during pregnancy that gives the maximum sample size of all; is finally taken as the main exposure variable to determine the sample size for the present study. Based on that, the percent of controls exposed (>50 kg) is 4.7%; Percent of cases with exposure is 12.5%, both estimated from another study . And, a 95% Confidence Interval, 5% Level of Significance (α) = 0.05 (two-sided), a Power of 80% and 2:1 allocation ratio of controls to cases are assumed. Using the formula, 151.9 ≈ 152cases were calculated. Adding 10% non-response rates i.e. ≈ 16; it became 168. The controls were twice the cases so were 336. And a total of 504participants were enrolled in the study.
In Addis Ababa, there are 12 public hospitals. Obstetric and neonatology services are available at six of the institutions. Of these three hospitals i.e. Gandhi Memorial, Yekatit-12 Medical College , and Zewuditu Memorial Hospitals were selected by simple random sampling technique. Then, both the cases and controls were then chosen at random from term babies delivered at each of the three hospitals. The number of cases selected from each of the three hospitals is allotted proportionally based on the total sample size to the total number of women who gave birth (with relation to recent experience /in the previous three months prior to the data collection period). The number of controls chosen from each hospital was decided by the number of cases assigned to the given hospital. In that, the number of controls that were selected from a given hospital was twice that of the number of cases allotted to the hospital. Finally, the study units were selected using a systematic random sampling technique every 3rd interval, after picking the first sampling unit at random using the list of medical record numbers and the registration book as a sampling frame.
The study was conducted in three governmental hospitals in the capital of Ethiopia, Addis Ababa. A total of 504 subjects (168 cases and 364 controls) were sampled using the large population formula. The data collection was carried out by record review and interviewing mothers using a document review checklist and a pre-tested structured questionnaire by phone call respectively. Trained BSc nurses collected the data, and the data collection process was supervised by health officers. For this purpose, two nurses at each hospital, or a total of six for all the three hospitals, and one Health Officer at each, or a total of three for all the three hospitals, were assigned to collect the data and supervise the data collection process, respectively. Overall, on every morning of the data collection period, the principal investigator went to the medical record unit of the hospital and examined the records of all birth cards for completeness of the records.
In this study, LBW was defined as a neonate with a birth weight of less than 2,500 grams. Through an interview using a structured questioners and checklist, the information was collected from the mother for socioeconomic characteristics and obstetrical history. A record review checklist was used for reviewing antenatal care cards. The weight and height of the mothers and birth weight of newborns were taken from the mothers‘records. Caliberation was used to insure that the instruments used in the hospitals to weigh the mother and new born were up to the standard.
- Socio-demographic characteristics, (newborn sex, maternal age, family monthly income, educational level, maternal occupation, religion, marital status, and others).
- Maternal and obstetrical characteristics (maternal weight, gravidity, parity, history of abortion, hemoglobin level, trimester of ANC visit, gestational age at birth, number of ANC follow up).
Data quality control
Data quality was ensured during collection, coding, entry, and analysis. A structured checklist was used for reviewing the charts of mothers and neonates. To avoid confusion and to create shared understanding of the study, data collectors and supervisors received training on its purpose. Each card was checked for its completeness and appropriate documentation. Supervision of data collectors included observations on how the data collectors collected the data, checking the correctness and completeness of records, and vigilant examination of completed checklists and questionnaires for cleanness and quality of recording.
The data collectors were instructed to write the card number on the checklist during the data collection so that any identified errors were traced back using the card number. The filled checklist was checked for completeness by data collectors, supervisors, and investigators on a daily basis. Consequently, any problem encountered was discussed among the team and solved immediately. Above all, prior to the actual data collection process, all data collection tools and procedures were pretested for their capacity of to generate valid and valuable information as desired. The reliability of the tools was checked using Cronbach's alpha (0.897) during the pre-test.
Data processing and analysis
The data was entered and categorized using EPI Info.7 software. It was then imported into the statistical package for the social sciences (SPSS) version 24 software for further analysis. Descriptive statistics were used to describe demographic and socio economic characteristics of the study participants and the distribution of the risk factors for low birth weight among the cases and controls using frequencies and percentages. A bivariate logistic regression analysis was used to assess the possible independent effect of each independent factor on the dependent variable, with the respective crude odds ratio (COR) and 95% confidence interval. While multivariable logistic regression analyses were used for those independent variables with <0.25 p-values of the bivariate logistic regression analysis result, to assess their adjusted effects on the dependent variable, using the adjusted odds ratio (AOR) and 95% confidence interval. For all associations, throughout the analyses in the present study, P-values <0.05 were considered statistically significant.
- Birth weight: is the first weight of the fetus or newborn obtained after birth, measured within the first hour of life before significant postnatal weight loss has been occurred by using a standard weight scale.
- Case: a neonate with a birth weight of less than 2, 500 gm.
- Control: a neonate with a birth weight 2, 500 gm. to 4, 200 gm.
- Extremely low birth weight (severely underweight): is the weight of neonate less than 1,000 gm.
- Low birth weight (underweight): is the weight of neonate less than 2,500 gm.
- Normal birth weight: a neonate with a birth weight 2, 500 gm. to 4, 200 gm.
- Term baby: an infant born completing the full terms of pregnancy (37 to 42 weeks).
- Very low birth weight: is the weight of neonate less than 1,500 gm.
The ethical review committee of Debre Berhan University's College of Health Science gave their approval. It was also communicated to Addis Ababa City's Health Bureau. The Addis Ababa Public Health Research and Emergency Management Core Process, as well as the respective department heads of the obstetric ward in each of the three hospitals, gave their approval for the cards to be used. Since the cards contain the mothers' names, confidentiality was maintained by instructing the data collectors not to report any personal information contained on the cards. Following that, the mothers of the newborns were contacted via phone to obtain informed consent.