Table 4.

Associations between specific opioid use from one month before conception and the end of pregnancy and preterm birth, National Birth Defects Prevention Study (controls), 1997-2011

	Preterm/ Term N (percent)	Crude OR (95 percent CI)	Adjusted† OR (95 percent CI)
Codeine
Any duration	19/151 (11.2)	1.5 (0.9, 2.4)	1.4 (0.8, 2.2)
Hydrocodone
Any duration	20/143 (12.3)	1.6 (1.0, 2.6)*	1.6 (1.0, 2.6)
Meperidine
Any duration	9/41 (18.0)	2.6 (1.2, 5.3)*	2.5 (1.2, 5.2)*
Morphine
Any duration	10/42 (19.2)	2.8 (1.4, 5.6)**	3.0 (1.5, 6.1)**
Oxycodone
Any duration	6/69 (8.0)	1.0 (0.4, 2.4)	1.1 (0.5, 2.5)

OR, odds ratio; CI, confidence interval.

^†Adjusted for maternal age at delivery, race/ethnicity, education, prepregnancy body mass index, maternal smoking between one month before conception and the third month of pregnancy, alcohol consumption between one month before conception and the third month of pregnancy, and study location.

^*p < 0.05.

^**p < 0.01.