Figure 1.

Changes factors associated with preterm birth in all pregnancies in China, 2012–18

Maternal age (A), number of antenatal visits (B), type of pregnancy (C), type of birth (D), and maternal complications (medical disease; eg, heart disease, embolism or thrombophlebitis, hepatic disease, severe anaemia [haemoglobin concentration of <70 g/L], renal disease [including urinary tract infection], lung disease [including upper respiratory tract infection], HIV/AIDS, connective tissue disorders, gestational diabetes, and cancer; E).