In this study, the prevalence of preterm births in this study was found to be 13.3%.
The result of this study was consistent with the study done in Debremarkos (2013) and India (2010) which reported with the prevalence of 11.6 % and 15% (Tigist et al.,, 2013: Shubhada Aet al.,, 2013). This similarity might be due to health care system in our country and service provided for mothers are almost uniform through out the different area of the country.
The finding of this study was higher than the study conducted in Gondar (2012), Iran Asali Hospital (2007) and Egypt (2014) which reported that the prevalence of preterm birth was 4.4% 6.3% and 8.2 % ((Kahsay, 2016, Tehranian et al.,, 2016: Ayman et al.,, 2015) respectively. This discrepancy might be due to difference in inclusion and exclusion criteria, study areas and due to difference in health care services provided.
The finding of this study was found to be lower than studies conducted in Nigeria (2010) with the prevalence rate of 24% (Kunle-Olowu et al.,, 2014). This might be due to the higher rate of multiple gestations in Nigeria, as this cause over distended uterus and can precipitate to preterm birth and multiple gestations is a known predisposing factor for preterm birth
The finding in this study was also lower than the study done in Kenya (2013), Brazil (2009) and India(2010) which reported that the prevalence were 18.3% and 21.7% (Wagura, 2014; Miranda et al.,, 2012). These discrepancies might be due to difference in study areas, methodological differences.
This study showed that residence was associated significantly with preterm birth. This finding was in line with the study done in Bahirdar (Getachew et al.,, 2015). This might be due low access of maternal care services and awareness differences of the mothers in the rural area with mother found in the urban area.
Short inter pregnancy (<24 months) was significantly associated with preterm birth. This finding was in consistence with the study conducted in Debremarkos since 2013(Tigistet al.,, 2013).. This is a risk factor for preterm birth and it might be due to existence of unidentified factors which precipitating preterm births in mothers with short inter pregnancy interval.
Previous preterm birth was another factor significantly associated with preterm birth found in this study. Mothers who had previous history of preterm births seven times were more likely to have preterm births compared to mothers who had no previous history of preterm births in the subsequent deliveries. This finding was in consistence with the secondary data analysis report of Malawi (2014): van den Broek et al.,, 2014). The possible reason might be due to existence of unidentified factors which precipitating preterm births in the subsequent deliveries.
According to this study, mothers who had premature rupture of membranes (PROM) during pregnancy were four times more likely to have preterm birth compared to those had no premature rupture of membrane. This finding was in consistence with findings of cross sectional studies conducted in Debremarkos (2013) and Kenya (2013) (Tigistet al.,, 2013, Wagura, 2014). This may be due to the fact that PROM elevated fetal plasma interleukin–6 indicating that this fetal response may trigger preterm labor correlated strongly with spontaneous delivery(Gravett et al., 2007).
Multiple gestations were significantly associated with preterm birth in this study. Mothers with multiple pregnancies were almost six times more likely to have preterm birth compared with mothers who gave birth singleton This finding was in line with the finding of study done in Kenya (2013) (Wagura, 2014). This might be due to multiple gestation is associated with uterine over distension and this may result in spontaneous preterm labour and also Multiple pregnancies can stretch the myometrium; this induces theoxytocin receptors, which results in preterm labor and delivery (Buxton, IL et al.,2010).
Chronic medical illnesses are significant variable associated with Preterm birth. Mothers with chronic medical disorders were almost seven times more likely to have preterm births compared to mothers who had not chronic medical disorders. This finding was in consistence with cross sectional study conducted in Debremarkos (2013) (Tigistet al.,, 2013). This might be might be due to maternal illnesses can limit or minimize the placental delivery of oxygen and nutrients to the developing fetus in the uterus possibly increase the risk of preeclampsia and, thus, increases the risk preterm birth. (Behrman, R. and Butler, A. 2007).
Besides to this, mothers who had malaria during their pregnancy were more and mothers who had exposed for malaria during pregnancy were five times were more likely to have preterm births than mothers who had not exposed to malaria during the pregnancy. This result was in line with the study done in Iran (2011–2013) (Pourfallah et al.,, 2015). This might be due to malaria affects placenta and contributes to maternal anaemia and placental parasitemia which leads to preterm labor which in turn result preterm birth (Marcus J. Rijet al., 2014).