Objective  To analyze the difference in perinatal outcomes between adolescent pregnancies and pregnancies at appropriate adult age.

  Methods  We extracted medical records of all 15 – 34 years old pregnant women hospitalized for their deliveries from the end of 2012 through 2017 in 22 hospitals covered by the Hebei Provincial Information Manage System for Critical Pregnancy in 10 cities across the province. Then we divided the pregnant women with complete information into an adolescent group (AG: 15 – 19 years old, n = 3 715), a younger group (YG: 20 – 24 years old, n = 54 218), and an elder group (EG: 25 – 34 years old, n = 185 022); the we analyzed perinatal outcomes among the participants.

  Results  Compared to those of the YG and EG group, the participants of AG group had a significantly higher ratio of spontaneous delivery (59.59% vs. 53.96% and 47.19%), but a significantly lower ratio of cesarean section (39.52% vs. 45.80% and 52.64.%) (P < 0.05). In contrast to among those of YG and EG group, significantly higher incidence rates of pregnancy complications and adverse pregnancy outcomes were observed among the participants of AG group, including severe preeclampsia (2.18% vs. 1.98% and 1.83%), premature birth (14.21% vs.11.13% and 12.65%), low birth weight infant (8.20% vs. 4.92% and 4.44%), intrauterine stillbirth (0.40% vs. 0.17% and 0.14%), and stillbirth (1.37% vs. 0.54% and 0.16%) but a significantly lower incidence rate of gestational diabetes (1.35% vs. 1.96% and 4.08%)(all P < 0.05).

  Conclusion  Adolescent pregnancy is associated with adverse pregnancy outcomes and increased incidence rate of preterm birth, low birth weight and perinatal mortality.