RURAL, LOW-INCOME, HIGH-ALTITUDE POPULATION: BURDEN, DETERMINANTS OF POSTDATE PREGNANCIES AND NEONATAL PHENOTYPE
Authors: Ogah Adenike Oluwakemi , Ogbole James Aaron 
Published: June 2023

Background

Conditions, which reduce oxygen delivery to the fetus, are associated with impaired intrauterine growth. Postdate babies are thought to be rare in today’s neonatal practice. The combined effects of prolonged gestation, high altitude and rural-low-income residence on fetal growth and hence timing of delivery, have been poorly investigated. This study examined and compared the burden, determinants and neonatal phenotypes of term and postdate pregnancies in a remote, high-altitude (1674m above sea level) community.

Subject and methods

This was the secondary analysis of the baseline data collected for a prospective cohort study. Healthy, 529 mother-singleton infant pairs were recruited consecutively from a rural district hospital. Newborns were classified by their gestational age and weight according to WHO. Gestational age was determined by mother’s LMP, fetal ultrasound dating and post-delivery ballard examination. Postdate was defined by gestation >40weeks. Preterm babies (26-4.9%) were excluded, remaining with 503 babies that were used in the analysis. Logistic regression models and chi test were used to compare the characteristics of term and postdate deliveries.

Results

Of the 503 mother-infant study participants, postdate babies were 199 (39.6%) and SGA babies were 108 (21.4%). Overall, SGA birth rate was 4 times higher than the preterm birth rate. There was greater odds of SGA birth (p<0.001; OR=11.05; 95% CI 3.74, 35.57), especially symmetrically growth retarded SGA (p=0.003; OR=6.60; 95% CI 1.67, 26.1) in postdate delivery compared to term delivery. Though birthweight was preserved, the rate of SGA delivery progressively increased from 14.3% at 38weeks to 80% at 43weeks gestation. The rate of AGA delivery peaked at 40 weeks gestation (85.6%) and thereafter declined. Maternal married status (p=0.009, OR=2.27) and high MUAC (p=0.049; OR =1.74) promoted postdate pregnancy. Mothers (80%, p=0.005) engaged in professional occupation had a tendency to prolonged pregnancy. Good environmental (water and toilet) sanitation was more likely to result in postdate delivery, p<0.05.

Conclusion and Recommendations

The rates of postdate and SGA births were unexpectedly high for the level of altitude. Unlike in low land studies, where prolonged pregnancies were associated with macrosomia, postdate deliveries in this high-altitude population, were more commonly associated with SGA birth and their complications. The strong association of symmetric SGA (rather than asymmetric SGA) with postdate pregnancies suggests longstanding intrauterine insult from probably combined effects of chronic hypoxia from high altitude residence and maternal factors. The authors of this study strongly recommend that high-altitude pregnancies should not be allowed to progress beyond 40weeks gestation and more resources should be committed to identifying high risk pregnancies with tendencies for prolonged pregnancies and improve maternal nutrition and oxygen status during pregnancy. Newborns should be classified at birth, their problems anticipated and managed appropraitely for an improved neonatal care, survival and wellbeing.