Study design, setting, period and populations
A prospective cohort longitudinal study was employed at Sawla General Hospital, Arba Minch General Hospital and Chencha district Hospital from first of March 2018 to 28th of February 2020. Among those hospitals, over four thousand newborns were delivered per year and more than 612 newborns were admitted to the neonatal intensive care unit (NICU) at each hospital15.
Follow up was started at diagnosis of perinatal asphyxia immediately after birth for those delivered at the hospital and at admission to the hospital for those delivered from 1st March 2018 and the follow-up period was closed on 28th February 2020. Follow-up was initiated immediately at the diagnosis of PNA and followed until seventh day of life. The follow-up was closed if the newborn was died, discharge with recovery, lost to follow-up from treatment, transferred to another institution and follow-up time ended without the event happening.
In this study, a newborn that withdrew treatment, discharged with recovery, transferred to another institution, and who did not yet develop the event at the end of the follow-up period was operationally defined as Censored. Sample size was estimated by Open Epi 3.02 statistical software using double population proportion formula in considering the assumptions; 95%CI, 80% power, exposed to unexposed ratio: 1, percent of unexposed with outcome (Not having history of premature rupture of membrane (PROM)): 50%, percent of exposed with outcome (Having history of PROM): 62%, AHR: 1.67 and considering 10% for non-response, the sample size became 573. Sample size was allocated to each hospital proportionally based on the number of the admitted cases and consecutive sampling method was applied (Figure 1).
The dependent variable was time to perinatal mortality and the independent variables were classified as socio-demographic factors (sex of the newborn, maternal age, marital status, a religion of the mother, maternal educational status, maternal occupational status, family size, place of residence, distance between home and hospital and estimated monthly income), obstetrics related characteristics (number of antenatal care (ANC) visits, gravidity, parity, number of pervaginal examinations, history of meconium-stained amniotic fluid, the onset of labor, history of antepartum hemorrhage, history of obstructed labor, history of premature rupture of membrane, history of prolonged rupture of membrane, cord prolapse, presentation of the fetus, mode of delivery and gestational age), newborn related factors (cry immediately at birth, history of convulsion or spasm and birth weight) and maternal medical related characteristics (history of PIH, maternal iron deficiency anemia, maternal diabetes mellitus, and maternal HIV status).
Perinatal Asphyxia: is a diagnosis when the newborn’s fifth minute APGAR score less than 7 OR complete absent respiratory effort immediately at birth.
Maternal Anemia: The hemoglobin level of a pregnant woman or early delivery mother less than 11gm/dl.
Premature rupture of the membrane: a rupture (breaking open) of the membranes (amniotic sac) before labor begins.
Prolonged rupture of membrane: a rupture of membranes lasting longer than 18-24 hours (i.e., between the time of rupture and time of delivery).
Convulsion: newborn who experience an episode of rigidity and uncontrolled jerky motions that generally last a minute or two along with altered consciousness.
Data collection procedure, quality control and analysis
Structured checklist was used to collect the data. Data extraction tool was carefully designed to improve data quality. In addition; both data collectors and supervisors were trained. Pretest was conducted (5% of the population). Sensitivity analysis was conducted. The maternal hemoglobin test results were obtained from a laboratory report which was prepared for this research purpose. The hemoglobin level was adjusted for altitude according to criteria set by WHO (World health organization).
Epi Data version 3.02 was used to enter the data, code the data, edit the data and clean the data. Finally, the data entered in to Epi Data were exported to SPSS version 25 for statistical analysis. The Kaplan Meier survival curve, together with a log-rank test, was used to estimate the survival time and the time which had higher risk of death. Variables that had a p-value <0.05 in bivariate analysis were considered as candidates for multivariable analysis and variables which had a p-value <0.05 in multivariable cox proportional hazard model were considered as statistically significant.
Ethical clearance was obtained from Arba Minch University, college of medicine and health sciences ethical review board. All participants provided an informed consent. Mothers were informed about the objective and significance of the study prior to the data collection. Appropriate measures were applied to ensure the confidentiality of the data.