“Risk factors of birth asphyxia”

However, Pakistan being the developing country, experiences a significant morbidity due to birth asphyxia and its sequel of complications. In Pakistan there is not much data available on the risk factors of birth asphyxia, hence studies are required to evaluate the risk factors of birth asphyxia so that interventions can be done to educate and guide people about the risk factors and management strategies. Our main goal was to evaluate the antepartum, intrapartum and fetal risk factors of birth asphyxia.

It was a Retrospective case control study conducted at the neonatal intensive care unit of pediatric ward (I, II, III) and at Gynecology ward (I, II, III) of Civil Hospital Karachi, one of the largest public sector, tertiary care hospitals in Karachi. Study was done from January 2011-November 2012.

Subjects were divided into cases and control. Neonates diagnosed with birth asphyxia were considered as “cases” while neonates born from normal vaginal delivery or by cesarean section with no abnormality were considered as “control”. Sample size was determined with the help of Open EPI calculator.

Diagnostic criteria of Birth Asphyxia:

Mild-Moderate Asphyxia: Apgar score at 1 min is 4–7

Exclusion Criteria were:

Apgar scoring consists of five physical sign: heart rate, respiratory effort, reflex irritability, muscle tone and color. Labor was considered prolonged when it exceed 12 hours in primigravida or 8 hours in multipara [10]. Fetal distress was diagnosed when fetal heart rate was recorded at less than 100/mm or more than 160 min or when it was irregular. Prolonged rupture was labeled when rupture of membranes was more than 18 hours before the birth of baby. Temperature of more than 99 F was considered as febrile. Anemia in antenatal period was defined as documented evidence of hemoglobin measurement of less than 11 gms/100 milliliter at any time prior to or after admission as emergency referrals. Premature rupture of membranes is defined as a condition in which rupture of the membrane of the amniotic sac and chorion occur more than one hour before the onset of labor. Information regarding diabetes, acidosis, striol level, surfactant test and ultrasound guided abnormalities were extracted from medical records.

Intrapartum: Event occurs during labor and delivery.

Antepartum: Event occurring before childbirth, with reference to the mother.

Maternal characteristic were obtained during interview of mothers, using pre-structured Performa.

Performa was filled on each case. Questionnaire comprises of 24 questions. 1st portion comprise of demographic data of neonate and mother. Q1-Q7 comprises of questions regarding age of mother, type of case (booked or not), any illness during pregnancy, drug and smoke history, type of pregnancy, history of diabetes, anemia and any previous history of birth asphyxia. Second section comprise of history of current pregnancy. It consist of questions from Q8-Q18, these were regarding any fetal condition diagnosed during pregnancy, presentation of fetus, mode of delivery, type of assisted vaginal delivery, anesthesia received during C-section, history of prolong labor, place of delivery, any emergency complication face by mother and history of sedation. Last section was regarding neonatal characteristic. It compromise of questions from 19–24, which consist of gestational age at birth, history of cry and seizure, about resuscitation, mode of resuscitation and birth weight. Information about the date and time of birth, gender, birth weight and result of Apgar score at 1, 5 and 20 minutes has been noted in questionnaire.

Study was approved from the institutional review board of Civil Hospital Karachi, Dow University of Health Sciences.

All data was entered and analyzed through SPSS 19. Mean and standard deviation were used for continuous data while frequency and percentage were calculated for categorical data. Risk factors for birth asphyxia were grouped into antepartum, intrapartum, and fetal variables. Association between birth asphyxia and risk factors was determined by Binary logistic regression. The percentage of risk factors associated with birth asphyxia at different intensity levels was estimated by odds ratio with the confidence interval CI of 95%. Threshold of significance was set at 0.05

Mothers at age of 20–25 were at higher risk of developing Birth asphyxia as compare to younger or elder mothers (<20 or >25) (OR 0.30, CI 95% 0.07-1.21,). Risk increased significantly with decline in booking status of mother (OR 0.20, CI 95% 0.11-0.37, p = <0.01). Pre-eclampsia was associated significantly with increase risk of birth asphyxia (OR 0.943, CI 95% 0.90-0.98, p = <0.01). Gestational diabetes was associated with development of birth asphyxia (OR 4.00, CI 95% 0.83-19.24, p = <0.06).

Maternal hypertension (p = 0.46), anemia (p = 0.10) and diabetes mellitus (p = 0.93) were not related to an increase risk of birth asphyxia (Table 1).

Infants of primiparous women carried a higher risk for birth asphyxia 70 (56.9%) as compared to normal 39 (33.3%) (OR 2.64 CI 95% 1.56-4.46, p = <0.01). Mother of neonates who developed birth asphyxia was mostly belonging to low socio economic group 62 (50.4%) and they have no prior history of abortion 102 (82.9%). Mothers having prior history of asphyxic child have more prone to birth asphyxia again as compare to control (OR 3.92 CI 95% 1.26-12.19) (Table 2).

Although the majority of births take place in hospitals but deliveries that took place at home and private clinics were more prone to the risk of developing Birth asphyxia 27 (22.0%) as compare to control 2 (1.7%) (OR 16.16 CI 95% 3.74-69.75, p = <0.01). Deliveries by midwives were significantly associated with increase risk of birth asphyxia (OR 0.17 CI 95% 0.05-0.51, p = <0.01). Normal vaginal delivery was frequent in both asphyxia 77 (62.6%) and control group 68 (58.1%) and there were also no association to be found with type of anesthesia received by mother. Breech presentation of fetus was significantly associated with increased risk of developing birth asphyxia (OR 2.96 CI 95% 1.25-7.02, p = 0.01) (Table 3).

Maternal fever ( OR 10.01 CI 95% 3.78-26.52, p = <0.01), umbilical cord complication like prolapsed umbilical cord (OR 3.36 CI 95% 0.90-12.54, p = 0.05), cephalopelvic disproportion (OR 4.09 CI 95% 1.47-11.53, p = <0.01), prolonged labor (OR 16.16 CI 95% 3.74-69.75, p = <0.01) and Spontaneous premature rupture of membrane (OR 9.25 CI 95% 3.75-22.81, p = <0.01) were significantly associated with increase risk of developing birth asphyxia (Table 4).

The risk for developing birth asphyxia was higher in the infant of weight 1–2 kg (OR 0.13 CI 95% 0.05-0.32, p = <0.01) as compared to the infant with weight of 2.5- to >3.5 kg. Prematurity carried a substantially higher risk of developing birth asphyxia, with gestational age of 34 to 37 weeks, increasing the risk of asphyxia by a factor of 0.34 (CI 95% 0.19-0.58). Fetal conditions like oligohydromnios (OR 0.92 CI 95% 0.88-0.97, p = <0.01), pre-mature delivery (OR 26.68 CI 95% 3.54-201.10, p = <0.01) and fetal distress (OR 1.69, CI 95%, 0.00-0.11 p = <0.01) were significantly associated with increment in the risk of developing birth asphyxia. Intra uterine mecoinum release was significantly present in asphyxia cases 24 (19.5%) (p = <0.001). Amniotic fluid surfactant test were found negative only in asphyxia cases 9 (7.37%) (Tables 5 and 6).

The strength of our study lies in its case control design. Previous studies of Pakistan have targeted few and selected risk factors but we discuss nearly each and every risk factors of birth asphyxia. All attempts were made to ensure that the data collected was reliable and the methods were reproducible. However, our study was not free from limitations.

Main limitation was that our study conducted in one tertiary care hospital of Karachi where mostly patients belong to the low and low middle class and data couldn’t predict the overall situation in the country. Second limitation was short sample size of the study which may have limited our ability to detect small differences. Furthermore, convenient sampling was employed, which may have led to selection bias, and hence was not truly representative of the population under study. Third limitation was that, for the evidence of anemia, diabetes and hypertension we mostly relied on the maternal history without consideration of when the events occurred and how long they were or how they were managed.

Our research opens the door of large proportion of research which needs on this topic to define more accurately the true burden of birth asphyxia in developing countries, contribution of common risk factors such as maternal malnutrition and infection and outcome of asphyxia, and to intervention strategies that can be applied at scale in developing countries.