Introduction: The fertility pattern of Brazilian population has changed considerably in the last decades. Socioeconomic and cultural inequalities can influence the age of the first gestation, and the identification of these inequalities is a fundamental aspect of the monitoring and evaluation of women's health care policies.
Objective: To analyze the age of women in their first gestation and the related factors in Brazil.
Methods: A cross-sectional study using data from the National Health Survey 2013, analyzing women aged 18 to 49 years and their age in the first gestation, categorized by sociodemographic variables.
Results: The North Region presented the highest percentage of pregnancy for the stratum of 10 to 14 years. The first pregnancy at the age of 15 to 19 years had the highest percentages for all regions, with a significant difference between the North and Southeast. The Southeast region obtained the highest percentage of the first pregnancy at the age of 30 to 39 years. The first pregnancy at the age of 15 to 19 years was significantly higher among the separated women; without instruction; and who live in rural areas. The first pregnancy of 10 to 14 was associated with the highest number of births that women will have throughout their lives, with a higher prevalence of 5 to 9 births.
Conclusions: In Brazil, a large proportion of first pregnancies still occur in adolescence. The states of the northern region stand out with lower average ages in the first pregnancy, and this event is related to the worst socioeconomic conditions.