Table 3.

Associations between medical and reproductive factors and urinary tract infection in pregnancy—cross-sectional analysis of the National Birth Defects Prevention Study, 1997–2011.

	Total number	Reported UTI prevalence (%)	Crude prevalence ratio (95% CI)	Adjusted prevalence ratioa (95% CI)
UTI before pregnancyb
Yes	1,112	28	1.54 (1.40, 1.70)	1.31 (1.19, 1.44)
No	40,719	18	1.00 (Reference)	1.00 (Reference)
Missing	38
Diabetes
Pregestational	786	26	1.43 (1.26, 1.61)	1.39 (1.24, 1.57)
Gestational	2,118	21	1.14 (1.05, 1.25)	1.18 (1.09, 1.29)
None	38,908	18	1.00 (Reference)	1.00 (Reference)
Missing	57
Previous pregnancies
0	12,694	20	1.00 (Reference)	1.00 (Reference)
1	11,651	17	0.87 (0.82, 0.92)	0.98 (0.93, 1.03)
2	8,067	17	0.88 (0.83, 0.93)	1.05 (0.99, 1.12)
3	4,657	19	0.94 (0.87, 1.00)	1.17 (1.09, 1.26)
4	2,422	19	0.97 (0.89, 1.06)	1.26 (1.15, 1.39)
5	1,178	18	0.92 (0.81, 1.04)	1.26 (1.10, 1.43)
6	521	21	1.06 (0.89, 1.25)	1.41 (1.17, 1.66)
≥7	616	19	0.93 (0.78, 1.09)	1.35 (1.13, 1.60)
Missing	63
Plurality
Singleton	39,623	19	1.00 (Reference)	1.00 (Reference)
Twins or more	2,192	17	0.90 (0.82, 0.99)	1.06 (0.96, 1.16)
Missing	54
Prepregnancy body mass index category (kg/m2)
Underweight (<18.5)	2,167	23	1.38 (1.27, 1.50)	1.13 (1.04, 1.23)
Normal weight (18.5–24.9)	20,733	17	1.00 (Reference)	1.00 (Reference)
Overweight (25.0–29.9)	9,183	18	1.08 (1.02, 1.13)	1.06 (1.01, 1.12)
Obesity (≥30.0)	8,000	21	1.24 (1.18, 1.30)	1.17 (1.11, 1.24)
Missing	1,786

CI, confidence interval; UTI, urinary tract infection.

^aAdjusted for birth defect status, study site, age at conception, race/ethnicity, and educational attainment.

^bUTI in the three months before pregnancy.