[A multicenter study of the birth condition of preterm infants and the causes of preterm birth in Henan Province, China].

Objective: To investigate the birth condition of preterm infants and the causes of preterm birth in Henan Province, China, and to provide a basis for the prevention and treatment of preterm birth.

Methods: An epidemiological investigation was conducted for live-birth preterm infants who were born in 53 hospitals in 17 cities of Henan Province from January 1, 2019 to December 31, 2019 to investigate the incidence rate of preterm birth, the distribution of gestational age and birth weight, the use of antenatal glucocorticoids, and the causes of preterm birth.

Results: The incidence rate of preterm birth was 5.84% (12 406/212 438) in the 53 hospitals. The proportions of preterm infants with gestational ages of < 28 weeks, 28 - < 32 weeks, 32 - < 34 weeks, and 34 - < 37 weeks were 1.58% (196/12 406), 11.46% (1 422/12 406), 15.18% (1 883/12 406), and 71.78% (8 905/12 406) respectively. The proportions of preterm infants with birth weights of < 1 000 g, 1 000- < 1 500 g, 1 500- < 2 500 g, 2 500- < 4 000 g, and ≥ 4 000 g were 1.95% (240/12 313), 8.54% (1 051/12 313), 49.53% (6 099/12 313), 39.59% (4 875/12 313), and 0.39% (48/12 313) respectively. The infants born by natural labor accounted for 28.76% (3 568/12 406), and those born by cesarean section accounted for 70.38% (8 731/12 406). The rate of use of antenatal glucocorticoids was 52.52% (6 293/11 983) for preterm infants and 68.69% (2 319/3 376) for the preterm infants with a gestational age of < 34 weeks. Iatrogenic preterm labor was the leading cause of preterm birth[40.06% (4 915/12 270)], followed by spontaneous preterm birth[30.16% (3 701/12 270)] and preterm birth due to premature rupture of membranes[29.78% (3 654/12 270)]. The top three causes of iatrogenic preterm birth were hypertensive disorders of pregnancy[47.12% (2 316/4 915)], fetal intrauterine distress[22.85% (1 123/4 915)], and placenta previa/placental abruption[18.07% (888/4 915)].

Conclusions: There is a relatively low incidence rate of preterm birth in Henan Province, and late preterm infants account for a relatively high proportion. Iatrogenic preterm birth is the main cause of preterm birth in Henan Province, and hypertensive disorders of pregnancy and fetal intrauterine distress are the main causes of iatrogenic preterm birth.