Material and Method: The secondary analysis of data from pregnant women aged 10 to 49 years, who were admitted to hospitals and recorded in the National Health Security Office database between October 2010 and September 2011 was carried out. Adolescent birth rate by the regions and rate of complications of pregnancy, delivery, and postpartum by age groups were analyzed.

Results: Highest birth rate was found among women aged 19 years (58.3 per 1,000 population). The distribution of adolescent births varied across regions of Thailand, which was high in central region. Rate of preterm delivery was highest (10%) in adolescent aged 10 to 14 years. Rate of diabetes mellitus (6%), preeclampsia (4%), and postpartum hemorrhage (3%) among women aged 35 to 49 years were substantially higher than those among women aged 34 years or less.

Conclusion: Adolescent birth rate varied across regions of Thailand. Complications occurred differently by ages of women. Holistic policy and planning strategies for proper prevention and management among pregnant women in different age groups are needed.

Keywords: Adolescent birth rate, Pregnancy complications, Hospital-based delivery