Study area and period
The multi-center institutional-based case-control study design was conducted among newborns in Arsi zone public hospitals from December 01, 2020 to May 30, 2020. The study was conducted in Arsi Zone Public Hospitals. Arsi Zone is located in Oromia Regional State Southeastern part of Ethiopia. The capital city of Arsi zone is Asella, which is 174 km away from Addis Ababa, the capital city of Ethiopia. The hospitals are Asella Referral Hospital, Bekoji, Abomsa, Robe, Gobessa, Kersa, Sude, and Bale District Hospitals.
Source and study population
The source population is all newborns delivered in Arsi Zone Public Hospitals. The study population is all newborns delivered in Arsi Zone Public Hospitals and fulfill the inclusion criteria during the study period.
Sample size determination and sampling procedures
The sample size was calculated by using Fleiss with continuity correction factor formula with a case-control ratio of 1:3; power of 80%, a significance level of 5%, the proportion of controls exposed (alcohol drinking) 55% , assuming the minimum odds ratio to be detected was 2. Using this value the expected percent of exposure among cases was 70%. The computed sample size was 418 (105 cases, and 313 controls).
All public hospitals found in the Arsi zone were included and an equal proportion allocation of samples was performed to include participants from each hospital. All mothers who delivered infants with congenital anomalies were invited to participate in the study. Mothers who delivered infants with no congenital anomalies were also included in the study using a systematic random sampling procedure. In the present study, all newborns with visible congenital anomalies and the next three newborns (delivered after cases) without congenital anomalies were included.
In our study, congenital anomalies are considered as the dependent variable. On the other hands, Socio-demographic characteristics (age, educational status, marital status, religion, ethnicity, income, occupation, husband’s education, and occupation), obstetric history (folic acid during and prior to pregnancy, history of antenatal care (ANC), contraceptive use, parity, gravidity, gestational age, family history of congenital anomalies, previous history of a child with congenital anomalies), medical condition-related factors (unidentified medication use, medical illness), drug and radiation (smoking and alcoholic history, khat chewing, use of herbal medicines, radiation, exposure to chemicals like pesticides), and others like sex of the newborn, consanguinity are considered as independent variables.
Cases:- are mothers who gave birth to babies with externally visible defects to any system of the body identified by clinical examinations by experienced medical doctors at the time of delivery.
Controls:- are mothers who gave birth babies without externally visible defects to any system of the body after clinical examination by experienced medical doctors at the time of delivery.
Consanguineous marriage:- couples related by blood at least to the second cousin.
Radiation:- Exposure to x-ray.
Data collection procedure
Data were collected using a pre-tested structured interviewer-administered questionnaire, which includes questions of socio-demographic, obstetric, medical, alcohol intake and smoking history, use of herbal medicine, exposure to chemicals, radiation, and folic acid supplementation (5 mg of folic acid was given throughout first trimesters from conception to 12th week of pregnancy). The questionnaire was prepared in English then translated into Amharic and Afan Oromo and then back to English by a third party who is native in Amharic and Afan Oromo respectively and good in English to ensure consistency of translation. Newborns were carefully examined and assessed for congenital anomalies by experienced medical doctors. Following a proper medical examination, the data were gathered from mothers regarding the information explained above using a structured questionnaire.
Six data collectors and six supervisors who are fluent in Amharic and Afan Oromo were involved in data collection. Accordingly, the supervisors were supervised respective data collectors during the data collection time and receive the collected and crosschecked questionnaires from them. Finally, the supervisors reported and discussed and crosschecked data with the investigator on a daily basis throughout the data collection period.
Data quality assurance
To maintain data quality, data collectors who are fluent in Amharic and Afan Oromo were selected based on their educational level and experience in data collection. Detail orientation and training about data collection and the purpose of the study were given to supervisors and data collectors by the principal investigator. Based on previous related peer-reviewed published studies, the questionnaire were developed by the investigators. A pretest study was conducted at Halila health centers on fifty individuals to see for validity and reliability of tools. The collected data were reviewed and checked for mistakes, completeness and consistency by the investigators and supervisors on a daily basis during data collection.
Data management and analysis
The collected data were coded, checked, and entered using Epi-Info version 7.0 and exported to IBM SPSS Version 21 for cleaning, checking for missing values, and analysis of data. Descriptive statistics and frequency tables were used to describe study populations.
Binary and multivariable logistic regression analyses were employed to assess the degree of association between dependent and independent variables. Those variables associated in binary logistic regression with a significance value of p-value ≤0.2 were entered into a multivariable logistic regression to identify predictors of CAs. A p-value ≤0.05 with 95% CI was considered statistically significant to identify significant factors associated with congenital anomalies. Hosmer-Lemeshow goodness-of-fit test was used to assess the fitness of the model.