Table 1.

Incidence of maternal mental illness hospitalization according to severity of preterm birth

	Total no. of women	No. of women hospitalized for mental illness	Incidence per 1000 person-years (95% confidence interval)	Cumulative incidence per 1000 women at 32 years of follow-up (95% confidence interval)
Preterm birth, weeks
<37	99,411	6362	3.81 (3.72-3.90)	119.9 (113.1-126.9)
<28	6716	399	3.84 (3.48-4.23)	116.0 (102.6-130.3)
28-31	8866	581	3.98 (3.67-4.32)	119.8 (107.0-133.3)
32-36	83,829	5382	3.79 (3.69-3.89)	120.1 (112.4-128.1)
≥37	1,281,889	66,789	3.01 (2.99-3.04)	96.8 (95.8-97.9)