Risk factors associated with low birth weight of neonates among pregnant women attending a referral hospital in northern Tanzania

According to the World Health Organization low birth weight (LBW) babies are those born with less than 2500g. Adescriptive retrospective cross -sectional study using existing data from a one-year (2001) block of birth registers of 3464 pregnant women was done at Kilimanjaro Christian Medical Centre in Moshi, Tanzania. The objective was to determine factors associated with LBW and their contribution to the problem. Out of 648 pregnant women who were tested for HIV infection 59 (9.1%) were positive for the infection. Twelve (20.3%) of HIV positive women gave birth to LBW neonates. HIV positive women were twice more likely to give birth to LBW infants than HIV negative ones (χ² = 6.7; P<0. 01; OR = 2.4; 1.1, 5.1). Mothers without formal education were 4 times more likely to give birth to LBW neonates than those who had attained higher education (OR= 3.6; 2.2, 5.9). There was a linear decrease in low birth weights of newborns as fraternal educational level increased (χ² for linear trend = 42.7; P< 0.01). There was no statistically significant difference among parents’ occupations regarding LBW of their newborns. Unmarried mothers were more likely to give birth to LBW neonates as compared to their married counterparts (OR = 1.65; 1.2, 2.2) and the difference was statistically significant (χ²=13.0, P< 0.01). Hypertension, pre-eclampsia and eclampsia disease complex had the highest prevalence (46.67%) and population attributable fraction of low birth weight (PAF = 25.2%; CI= 22.0-27.6). Bleeding and schistosomiasis had the same prevalence (33.33%) of LBW babies. Other complications and diseases which contributed to high prevalence of LBW included anaemia (25%), thromboembolic diseases (20%), tuberculosis (17%) and malaria (14.8%). Prevalence of LBW was high in women with premature rupture of membrane (38%), placenta previa (17%) and abruption of placenta (15.5%). LBW was strongly associated with gestational age below 37 weeks (OR = 2; CI=1.5, 2.8) contributing to 42% of LBW deliveries in the study population (PAF = 42.4%: 25, 55). Pregnant women with malnutrition (BMI<18) gave the highest proportions 17% of LBW children followed by underweight (BMI; 18-22) who gave 15.5% of LBW neonates. There was a statistical significant difference between the proportions of LBW infants from mothers who did not receive antenatal care (28.6%) and those who attended for the services (13.8%) (χ² = 8.8; P= 0.01). There is need of increasing promotion of reproductive health services in relation to safe motherhood at community level in order to reduce risk factors of LBW.