Table 5.

Associations Between Prenatal Care Indicators and Preterm Delivery

	Entire Sample	Term Delivery	Preterm Delivery	P value	Preterm OR	95% CI
Pregnancy intention (n = 549)				0.72^*
Intended (REF)	331	229 (69.2)	102 (30.8)		---	---
Unintended	218	154 (70.6)	64 (29.4)		0.93	0.64-1.36
Prenatal intake visit (n = 660)				0.61^*
Intake visit <12 wks gestation (REF)	567	381 (67.2)	186 (32.8)		---	---
No intake visit <12 wks gestation	93	60 (64.5)	33 (35.5)		1.13	0.71-1.78
Multivitamin use (n = 169)				0.17^*
≥3 Months of prenatal use (REF)	96	51 (53.1)	45 (46.9)		---	---
<3 Months of prenatal use	73	31 (42.5)	42 (57.5)		1.54	0.83-2.84
Tobacco avoidance (n = 653)				0.80^*
Yes (REF)	583	391 (67.1)	192 (32.9)		---	---
No	70	48 (68.6)	22 (31.4)		0.93	0.55-1.59
Depression screening (n = 542)				0.68^*
Negative (REF)	482	341 (70.7)	141 (29.3)		---	---
Positive	60	44 (73.3)	16 (26.7)		0.88	0.48-1.61
BMI (n = 647)				<0.001^*
BMI >18 and <30 (REF)	374	274 (73.3)	100 (26.7)		---	---
BMI ≤18 and ≥30	273	163 (59.7)	110 (40.3)		1.85	1.33-2.58
STI screening (n = 622)				0.07^*
Negative (REF)	604	422 (69.9)	182 (30.1)		---	---
Positive	18	9 (50.0)	9 (50.0)		2.32	0.91-5.94
A1c goal (n = 59)				0.07^*
<6.5 (REF)	43	22 (51.2)	21 (48.8)		---	---
≥6.5	16	4 (25.0)	12 (75.0)		3.14	0.87-11.30
Teratogenic medication use (n = 661)				0.33^†
No (REF)	660	440 (66.7)	220 (33.3)		---	---
Yes	1	0 (0.0)	1 (100.0)		n/a	n/a
Blood pressure (n = 634)				0.002^*
<120/80 (REF)	364	264 (72.5)	100 (27.5)		---	---
≥120/80	270	165 (61.1)	105 (38.9)		1.68	1.20-2.35
Harmful drug use (n = 653)				0.69^*
Avoided harmful substances (REF)	604	402 (66.6)	202 (33.4)		---	---
Use of harmful substances	49	34 (69.4)	15 (30.6)		0.88	0.47-1.65

↵* Chi-square test-of-independence.
↵† Fisher’s Exact test. Highlighted values indicate statistical significance.
Abbreviations: OR, Odds ratio; CI, Confidence interval; REF, Reference; Wks, Weeks; BMI, Body mass index; STI, Sexually transmitted infection.