The burden of preterm birth remains a public health issue worldwide, and a significant cause of morbidity and mortality among neonates and children.2, 13 The current study aimed to scrutinize factors that could determine preterm birth. According to the study finding, rural residence, short birth interval, intimate partner violence (IPV) during pregnancy, APH, and PROM during pregnancy showed statistically significant association with preterm birth at a 95% confidence level.
Mothers who brought birth within two years of previous delivery were four times more likely to have a preterm baby compared to those who prolong their pregnancy more than two years after the birth of their earlier child. This finding is consistent with reports of previous studies conducted in Nigeria22, Baghdad, Iraq23, Northern Tanzania24, and a systematic review by Conde-Agudelo et al.25 Several reasons could be stated for this association. The mother’s nutritional status is expected to be depleted because of the previous pregnancy requiring sufficient time to recover to normal physiological needs. A short birth interval might compromise this recovery time so that the mother could not be able to support the fetus to fulfill growth and development requirements. This inadequate nutrient supply could, in turn, lead to physiological competition between the fetus and the pregnant mother and finally end up with undesired perinatal consequences such as preterm birth.26 Furthermore, mothers who conceive shortly after the birth of their previous baby were expected to have diminished iron and folic acid reserves and thus anemia. Folate deficiency interferes with collagen cross-linking, resulting in weakened connective tissue. This weakened tissue could expose to PROM and bring their current child prematurely.25–27 On the other hand, the maternal blood vessels supplying the endometrial wall might not have a chance for effective remodeling after the delivery of the previous child. This could interfere with the uterine and placental perfusion, resulting in preterm birth.22
The finding also showed that the risk of prematurity among neonates delivered from mothers identified as having APH was 7.27 times higher than their counterparts. Our study result is supported by findings of previous studies done by Jhpiego28 and Wasrik et al in India.29 This could be rationalized by the possible maternal and fetal complications imposed by APH. When there is APH, the blood perfusion to the uterus and the placenta will be decreased. This, in turn, could compromise the placental oxygen and nutrient supply to the fetus resulting in early expulsion of the fetus either spontaneously or iatrogenically.30, 31
Likewise, the odds of preterm birth were 5.21 times higher among mothers who experienced PROM compared to mothers who did not have PROM. The finding of a study conducted in Tamil Nadu, India was conformable with our finding that two-thirds of neonates born from mothers who had PROM were born preterm.32 Other studies carried out in Indonesia, Cilegon hospital33 and Gondar town20 also reported similar findings. The possible justification might be the activation of pro-inflammatory markers following PROM. The release of these cytokines stimulates the decidual layer of the uterus and the fetal membrane. This stimulation might facilitate the release of prostaglandins and enzymes such as metalloproteinase. Consequently, this may lead to an increased risk of intrapartum infection, cervical wall thinning, enhanced uterine contraction, and finally, stimulation of preterm labor.33
Furthermore, mothers who suffered from IPV were at an increased risk of preterm birth than those who did not. Similar findings were published from other studies conducted in Peru34, Tanzania35, and Tigray.36 Violence could be committed against the victim physically, psychosocially, or sexually. Physical violence that involves the victim's abdomen might cause placental damage, rupture of membranes, and thus untimed uterine contraction resulting in preterm labor. On the other hand, women who suffered from other forms of violence such as psychosocial violence could develop anxiety, depression, and behavioral changes such as alcohol consumption and smoking. These consequences were highly linked to premature initiation of labor and inadequate prenatal fetal weight gain.37–39 Besides, mothers who developed stress and depression after experiencing violence were found to have altered cell adhesion molecules, pro-inflammatory cytokines, and raised C-reactive proteins. This could again lead to endothelial dysfunction and systemic inflammation, hence, placental insufficiency, abruption, and preterm birth.37, 39
The other factor that was independently associated with prematurity was the area of residence. Mothers who reside in rural areas were 3.72 times at higher risk of bringing premature babies than those who reside in urban settings. This finding is in line with the findings of the study conducted in the Tigray region, Axum, and Adwa public hospitals.21 The possible explanation for this could be multifactorial. First, mothers who resided in rural areas might not receive professional advice and support. Conversely, mothers may miss ANC follow-up visits due to distant settings, living standards (work overload), lack of partner support, poor perception, and cultural barriers. Second, inadequate nutritional intake in terms of nutrient composition could result in the depletion of fetal nutritional supply. Additionally, poor utilization of family planning and reproductive health services in rural areas could lead to unplanned and frequent pregnancies and thus, increased the chance of preterm birth.