Retracted: Folic acid supplementation, dietary folate intake during pregnancy and risk for spontaneous preterm delivery: a prospective observational cohort study

Table 5 Timing of folic acid supplementation and risk of spontaneous preterm delivery (sPTD)

sPTD	Time of olic acid		Unadjusted			Adjusted¹
	supplementation	n	HR	(CI)	p	HR	(CI)	p
	>8 w pre-conceptional	428	1.16	(1.04–1.30)	0.01	1.16	(1.02–1.31)	0.02
All	0-8 w pre-conceptional	572	1.02	(0.93–1.13)	0.64	1.04	(0.92–1.17)	0.52
	1st trimester	1185	0.94	(0.84–1.05)	0.25	0.88	(0.78–0.99)	0.04
	2nd trimester	795	1.11	(1.01–1.23)	0.03	1.10	(0.99–1.21)	0.08
	>8 w pre-conceptional	79	1.39	(1.07–1.80)	0.01	1.34	(0.99–1.80)	0.06
Early	0-8 w pre-conceptional	103	1.21	(0.94–1.55)	0.13	1.18	(0.88–1.58)	0.26
	1st trimester	199	1.07	(0.81–1.42)	0.62	0.94	(0.69–1.28)	0.67
	2nd trimester	137	1.26	(0.99–1.60)	0.06	1.18	(0.91–1.51)	0.21
	>8 w pre-conceptional	349	1.12	(0.99–1.27)	0.07	1.13	(0.98–1.29)	0.09
Late	0-8 w pre-conceptional	469	0.99	(0.89–1.11)	0.88	1.01	(0.89–1.15)	0.84
	1st trimester	986	0.91	(0.81–1.03)	0.14	0.87	(0.76–0.99)	0.04
	2nd trimester	658	1.09	(0.98–1.21)	0.13	1.08	(0.97–1.21)	0.17

Folic acid supplementation at different times (Q1 and Q3 data) and hazard ratios for spontaneous PTD (n = 1,628 for 22⁺⁰-36⁺⁶ weeks, n = 264 for early (22⁺⁰-33⁺⁶), n = 1,364 for late (34⁺⁰-36⁺⁶)). Cox regression for 65,668 participants in the Norwegian Mother and Child Cohort Study (2002 – 2009). Iatrogenic deliveries have been censored in the regression model.
¹ Cox regression, adjusted for maternal age, prepregnancy BMI, parity, history of PTD and spontaneous abortion, child’s sex, smoking habits and alcohol consumption during pregnancy, maternal education, marital status, household income, energy intake and dietary folate intake. Mutual adjustment for folic acid supplementation at other time points.

ISSN: 1471-2393