Table 2

Association between preterm birth in first pregnancy and preterm birth in the second pregnancy within gestational age categories at first birth. Matlab, Bangladesh, 1990 to 2019 (n=14,567)

Gestation age at first birth (weeks)	Second pregnancy
	Term birth (n=12 442)	Preterm birth (n=2125)	Preterm birth odds
			Crude		Adjusted*
			OR	95% CI	Adjusted OR†‡	95% CI
<32	117	63	4.74	3.46 to 6.48	4.06	2.95 to 5.58
32–33	288	141	4.31	3.48 to 5.33	3.59	2.89 to 4.46
34–36	1455	451	2.73	2.40 to 3.09	2.34	2.06 to 2.66
37–38	2910	598	1.81	1.61 to 2.02	1.72	1.54 to 1.93
≥39§	7672	872	1	1	1	1

*Hosmer and Lemeshow goodness-of-fit test p=0.106.
†Adjusted for maternal education, socioeconomic status by wealth quintiles and calendar year of second birth.
‡P_{-linear trend} = 0.001 by Wald χ² test.
§Reference category.