Urinary tract infection (UTI) is the single commonest bacterial infections of mankind, to help in alleviating the problem we previously conducted a study on UTI which addressed the bacterial profile and antibiotic susceptibility pattern of UTI [1, 2] but there was a need to address associated risk factors of UTI which may play important role in the prevention and control of this serious health problem which affect millions of people each year and which also lead to Gram-negative bacteremia [1, 3]. UTI is not only common but the range of clinical effect varies from asymptomatic bacteriurea (ABU) to acute pyelonephritis [4]. Women with ABU during pregnancy are more likely to deliver pre-mature or low-birth-weight infants and have a 20 to 30-fold increased risk of developing pyelonephritis during pregnancy compared with women without bacteriuria [5]. Untreated ABU can also leads to the development of cystitis in approximately 30% of cases. In addition acute pyelonephritis has been associated with anaemia [6]. ABU may also be associated with an increase in neonatal mortality and a source for Gram negative septicaemia [7]. In addition it also associated with pre-eclampsia and chronic renal disease that has been cited as significant adverse obstetric outcome and medical conditions [8].

Pregnancy is one of the factors which increase the risk of UTI partly due to the pressure of gravid uterus on the ureters causing stasis of urine flow and is also attributed to the humoral and immunological changes during normal pregnancy [9]. During pregnancy there are a number of conditions associated with an increased prevalence of UTI [10]. UTI is common with varying prevalence by age, sexual activity and the presence of genitourinary abnormalities [5]. In healthy women, the prevalence of bacteriuria increases with age from about 1 percent in females with 5 to 14 years of age to more than 20 percent in women at least 80 years of age [5]. The prevalence is higher among individuals in lower socioeconomic classes and those with a past history of UTI [11]. Sickle cell traits, diabetes mellitus and grand multiparity have been reported; each is associated with two-fold increase in the rate of bacteriuria [10]. There is also increase in the risk of developing UTI due to catheterization, spermicidal contraceptive usage, kidney stones, tumors and urethral strictures [9, 12]. Similarly increase risk of UTI reported in the presence of neurological diseases, congenital/acquired anomalies of bladder, vesico-ureteric reflux and suppressed immune system [9, 12].

Though there are few studies [13–15] conducted on prevalence and antibiotic susceptibility pattern of UTI, there is no study conducted on associated risk factors of Urinary tract infection (UTI) in Ethiopia particularly in Bahir Dar town. Therefore, this study was designed to assess associated risk factors of UTI among pregnant women attended the antenatal care clinic of Felege Hiwot Referral Hospital, Bahir Dar, North West Ethiopia.

The methods were previously described in our study on “Urinary Bacterial Profile and Antibiotic Susceptibility Pattern of UTI among Pregnant Women in North West Ethiopia” except few differences [1].

A total of 367 pregnant women (37 symptomatic and 330 asymptomatic pregnant women) were investigated for the presence of risk factors associated with urinary tract infections.

The assessment of associated risk factors of UTI showed that history of UTI (P = 0.000, OR = 3.397, CI = 1.672, 6.902), anaemia (P = 0.003, OR = 4.388, CI = 1.776, 10.839), sexual activity (P = 0.032, OR = 3.520, CI =  1.197,10.363) and family monthly income (taking family monthly income > 2000 birr ($151.40) as reference, family monthly income level ≤ 500 ETB ($37.85); P = 0.006, OR = 5.581, CI = 1.658, 18.793 and 501–1000 ETB($37.85-75.70); P = 0.039, OR = 3.429, CI = 1.065, 11.034) showed statistical significant association with UTI.

Factors proposed to affect the frequency of bacteriuria during pregnancy include multiparity, gestational age, previous medical history of UTI, diabetes mellitus and anatomic urinary tract abnormalities [7, 9, 10, 16–18]. In addition anaemia, socio-economic status, educational status, sexual activity and catheterization are also associated with increased risk of UTI [7, 9, 10, 16–18].

To our knowledge this is the first study to assessed associated risk factors of UTI among pregnant women in the study area. In our study socioeconomic status, anaemia, sexual activity and history of UTI were shown to be the associated risk factors with UTI among pregnant women.

Our study findings showed that low socioeconomic status was one of the factors that were significantly associated with increased UTI. The frequency of UTI (18.9%) was higher among pregnant women who had family monthly income of less than 500 Ethiopian birr ($37.85) and 501–1000 Ethiopian birr ($37.93-$75.70) for the overall UTI. Similarly study on the same study subject in Pakistan by Haider et al[6] also showed that pregnant women who had low income level were more likely to have bacteriuria than those who had high socioeconomic income level. Another study in Egypt by Dimetry et al[19] on UTI also showed the presence of association between low income level and UTI. This could be due to the relation of low socioeconomic status with nutrition and immunity especially in pregnant women. On the contrary some studies reported the insignificant association between UTI and socio economic status [18, 20].

Maternal anaemia was also significantly associated with UTI. Similar result were reported by different investigators such as study on UTI by Haider et al[6] in Pakistan, Taher et al[21] among asymptomatic pregnant women in Qatar, Enayat et al[10] among asymptomatic pregnant women in Iran and Sescon et al[7] among asymptomatic pregnant women in Philippines. This could be due to pregnant women with maternal anaemia are more likely to develop UTI than those who are not anaemic. The high probability of developing UTI among anaemic pregnant women may be related with immunity. A study on UTI by Kovavisarach et al[20] in Thailand reported the absence of association between anaemia and UTI.

The finding of this study also revealed that past history of UTI had strong association with UTI (P = 0.000, OR = 3.397, CI = 1.672, 6.902). Similar findings were reported by Haider et al[6] on UTI in Pakistan, Taher et al[21] in Qatar and Sescon et al[7] in Philippines among asymptomatic pregnant women. Masinde et al[22] also identified that past history of UTI is a risk factor for UTI during pregnancy. But absence of association was reported by Hamdan et al[23] in Sudan and by Kovavisarach et al[20] in Thailand.

Sexual activity was also the other associated risk factor that was found to be significantly associated with UTI. Pregnant women who had recent sexual intercourse of three or more per week were more likely to have UTI than women who had less than three intercourses per week. This may be due to sexual activity increases the chances of bacterial contamination of female urethra. Having intercourse may also cause UTIs in women because bacteria can be pushed into the urethra [3]. The anatomical relationship of the female urethra to the vagina makes it liable to trauma during sexual intercourse as well as bacteria can also be massaged up from the urethra into the bladder during pregnancy/child birth [3, 24]. This finding is also in agreement with previous studies by Hooton et al[25] on UTI in Washington, Haider et al[6] on UTI in Pakistan and Amiri et al[17] on UTI among pregnant women in Iran.

Multiparity was associated with significant bacteriuria in pregnancy. This had been repeatedly recognized to cause a two-fold increase in the rate of ABU in pregnant women [8, 26]. The association between multiparity and UTI is due to profound physiologic changes affecting the entire urinary tract during pregnancy has a significant impact on the natural history of UTI during gestation. These changes vary from patient to patient and are more likely to occur in women who have pregnancies in rapid succession [7]. According to this study parity was not significantly associated with UTI in pregnancy. This finding is in line with different studies throughout the world such as study by Hamdan et al[23] on UTI in Sudan, Masinde et al[22] on UTI in Tanzania, Turpin et al[11] among asymptomatic pregnant women in Ghana and Hazhir et al[27] among asymptomatic pregnant women in Iran. On the other hand other studies reported the presence of association between multiparity such as studies by Okonko et al[3] on UTI in Nigeria, Enayat et al[10] on asymptomatic pregnant women in Iran, Haider et al[6] on UTI in Pakistan.

There was no significant difference in the prevalence of UTI with respect to trimester. This is similar with earlier studies by Hamdan et al[23] on UTI in Sudan, Sheikh et al[18] on UTI in Pakistan, Masinde et al[22] on UTI in Tanzania, Hazhir among asymptomatic pregnant women [27] in Iran, Kovavisarach et al[20] on asymptomatic pregnant women in Thailand. Likewise level of education was also found to be not significantly associated with UTI. Similarly other studies also reported the absence of association between level of education and UTI among pregnant women such as study on UTI by Sheikh et al[18] in Pakistan, Masinde et al[22] on UTI in Tanzania, Hazhir [27] among asymptomatic pregnant women in Iran. There was no statistical significant association between age of the pregnant women and UTI. Similar finding also reported by Hamdan et al[23] on UTI in Sudan and Kovavisarach et al[21] on asymptomatic pregnant women in Thailand. The differences in results about the presence and absence of association between associated risk factors and UTI among different studies may be due to differences in methodologies, study population (living standard) and sample size used in the studies.

In this study the chance of UTI was higher among pregnant women in the presence of associated risk factors such as anaemia, low income level, past history of UTI and sexual activity but there was no significant association between prevalence of UTI and risk factors such as multiparity, history of catheterization, genitourinary abnormality, maternal age, gestational age and educational status of pregnant women. Therefore pregnant women should be assessed for associated risk factors during their regular follow up.