Trends and factors associated with adolescent pregnancies in Tanzania from 2004-2016: Evidence from Tanzania Demographic and Health Surveys.

Background: Adolescent pregnancy increases the risk of maternal and child morbidity and mortality. We aimed to determine trends and factors associated with adolescent pregnancy in Tanzania from 2004 to 2016 using the Tanzania Demographic and Health surveys (TDHS).

Methods: We carried out an analytical cross-sectional study using the TDHS data for the years 2004 to 2005, 2010 and 2015 to 2016 among adolescent girls aged 15 to 19 years. Data analysis was performed using STATA version 15. Data analysis considered the complex survey design inherent in the demographic and health survey (DHS) data. The Poisson regression model was used to estimate Prevalence Ratios (PR) and 95% confidence intervals for factors associated with adolescent pregnancy.

Results: We analysed data for a total of 10,972 adolescents for the three TDHS rounds. The proportion of adolescent pregnancy significantly decreased from 26% to 22.8% from the year 2004/05 to 2010 and then increased again to 26.7% in 2015/16. Adolescents who were aged 18 to 19 years (APR 1.52; 95% CI, 1.38 to 1.68) married or cohabiting with their partners (APR 2.15; 95% CI, 1.93 to 2.40; P<.001), widowed/divorced/separated (APR 2.32; 95% CI, 2.03 to 2.66; P<.001), and among those who started sexual activity before 15 years of age (APR 1.20; 95% CI, 1.11 to 1.31; P<.001) were more likely to become pregnant during adolescence. In contrast, adolescents with secondary school education level and above were the least likely to become pregnant (APR 0.62; 95% CI, 0.51 to 0.75; P<.001) compared to those with no formal education.

Conclusion: One in four adolescent girls aged 15 to 19 in Tanzania have already started childbearing and despite fluctuation, high rate of adolescent pregnancy persists. Preventive interventions should focus on adolescents with low education level, married/cohabiting with their partners, and who have started sex before 15 years of age. We advocate for the increase of school attendance until high school level to reduce the risk of early pregnancy in adolescents. Furthermore, qualitative studies are crucial to explore reasons for the rising trend of adolescent pregnancy in most zones of Tanzania, particularly between 2010 and 2015/16.