Study area, period and design.
The study was conducted at Saint Paul’s Hospital Millennium Medical College(SPHMMC), Addis Ababa, Ethiopia from September 2018-February 2019. SPHMMC is a tertiary teaching referral hospital under Federal Ministry of Health (FMOH). According to the statistics office of the hospital, nearly 50,000 attended antenatal care and around 10,000 deliveries were attended in 2018,35 % of deliveries being by cesarean section. In this hospital OBGYN specialists and 3rd and 4th year, OBGYN residents perform ultrasound including UA Doppler for diagnosis and monitoring of IUGR fetuses. This was a hospital-based comparative prospective cohort study to determine the perinatal outcome of growth-restricted fetuses with abnormal umbilical artery Doppler waveforms compared to growth-restricted fetuses with normal umbilical artery Doppler waveforms among pregnant mothers complicated with IUGR and admitted to labor and delivery room for pregnancy termination during the study period.
Inclusion criteria considered for the study were: singleton intrauterine pregnancy having Antenatal care (ANC) follow up, delivery and neonatal care at SPHMMC whose gestational age was >28 completed weeks by reliable last normal menstrual period (LNMP) or by early ultrasound of less than 24 weeks, diagnosed to have IUGR by ultrasound with UA Doppler study done by OBGYN specialists, and/or 3rd and 4th-year OBGYN residents. Patients with lethal congenital anomalies, Intrauterine fetal death before having Doppler studies and unknown last normal menstrual period and no ultrasound before 24 weeks were excluded.
Sample size and sampling procedure.
The sample size was calculated with using info stat calc version 7, for cohort study. Pregnant mothers complicated with IUGR which had abnormal UA Doppler studies were labeled as an exposed group, and pregnant mothers complicated with IUGR which had normal UA Doppler studies were labeled as a non-exposed group. Considering perinatal mortality of 28% in the exposed group and 6% in non-exposed groups(10), using the power of 80% and confidence interval (CI) of 95%, the calculated sample size was 150, adding a 10% loss to follow up gave a total sample size of 170. The ratio of non-exposed to exposed was taken as 3.6:1. So 37 cases of the exposed group and 133 cases of the non-exposed group were collected consecutively for comparison for six months.
Study variables: -
Abnormal umbilical artery doppler waveform.
Confounding variables considered were: Age, place of residence, level of education, occupation, marital status, parity, gestational age, mode of delivery and hypertension
Perinatal outcomes (prematurity, Birth weight, APGAR score, the need for resuscitation, NICU admission, RDS, neonatal sepsis, perinatal mortality).
Normal UA Doppler waveform: Normal Doppler indices (between 10th and 95th centile) and positive end-diastolic velocities.
Abnormal UA Doppler waveform: Raised (above 95th centile) indices (S/D ratio, RI, and or PI) or absent or reversed UA doppler flow.
Prematurity: delivery after 28 weeks but before 37 weeks of gestational age.
Non-Reassuring Fetal Heart Rate Pattern (NRFHRP): abnormal fetal heart rate is considered as a non-reassuring fetal heart rate pattern in this study.
Low 5th Apgar score: 5th minute Apgar score of < 7.
Neonatal Intensive Care Unit(NICU) admission: those neonates admitted to NICU.
Respiratory Distress Syndrome(RDS): also known as hyaline membrane disease (HMD), is a respiratory disorder of premature babies, in this study is a clinical diagnosis considered by the neonatal care team.
Neonatal sepsis: is a type of neonatal infection and the diagnosis of which is considered by the neonatal care team clinically or confirmed microbiologically as the presence of bacterial bloodstream infections such as meningitis, pneumonia, urinary tract infection, or gastroenteritis, in the setting of fever.
Perinatal mortality: in this study its intrapartum fetal death plus the death of neonates in the first seven days (early neonatal deaths) per 1000 live Birth.
Intrauterine growth restriction: birth weight below the 10th percentile for a given gestational age.
Data collection procedure and instrument.
A structured and pretested English questionnaire were used to assess sociodemographic characteristics, obstetric factors, umbilical artery Doppler waveforms, and the neonatal outcomes Two trained midwives working at labor and delivery room collected data by interviewing the mother and reviewing the maternal and neonatal chart. The phone number of mothers and their card numbers were recorded for the latter tracing of neonatal outcomes.
Data collection was started at the time the women were admitted to the labor and delivery room and were continued through the intrapartum course until delivery. The neonates who were not referred to Neonatal Intensive Care Unit (NICU) were followed until mothers discharged and those neonates which were referred to NICU were followed in the NICU. The status of all neonates was checked at the seventh neonatal day. Those admitted to NICU were checked at NICU for the outcome and all those discharged home before the 7th day was checked during follow up visits. Those who didn’t appear on follow up were reminded by cell phone call. Principal investigator supervised data collection and checked for completeness, accuracy, and consistency of all questionnaires.
Data processing and analysis.
Data cleaning was performed to check for outliers, missed values, and any inconsistencies before the data were analyzed using the software. Data were entered and analyzed using SPSS version 23. A chi-square test was used to check statistical associations between abnormal UA Doppler and outcome variables and covariates. Outcome variables with P value less than 0.05 were selected, and cross-tabulation was done to determine the strength and direction of the association between abnormal UA Doppler and each outcome variable. All covariates with P value less than 0.05 (covariates associated with exposure variable) were selected for binary logistic regression to determine their association with each outcome variable. Statistical significance of the association between exposure and outcome variables were determined by a 95% confidence interval and p-value set at 0.05. Adjusted Odds Ratio (OR) was used to determine the strength and direction of the association between exposure and outcome variables.
Ethical approval was obtained from Saint Paul's Hospital Millennium Medical College ethical review committee. Written informed consent to conduct the study and publish the outcome was obtained from each patient and confidentiality was maintained during data collection, analysis, and interpretation. All the datasets used and/or analyzed during the current study are included in the manuscript and available from the corresponding author on reasonable request.