Table 4 Open in new tab Association...

Time-dependent medication exposure after gestational day 139^a

Preterm birth

Person- weeks

Rate (per 1000/ week)

Crude HR (95% CI)

Adjusted HR^b (95% CI)

Mutually adjusted HR^c (95% CI)

Oral corticosteroid

253

4530

11.3

2.81 (1.80, 4.39)

1.64 (0.92, 2.92)

1.83 (1.01, 3.32)

No oral corticosteroid

368

7415

4.2

Reference

B-DMARD

215

4146

6.0

0.90 (0.56, 1.44)

0.91 (0.56, 1.47)

0.85 (0.52, 1.37)

No B-DMARD

389

7798

7.3

Reference

NB-DMARD

102

2092

5.7

0.83 (0.45, 1.53)

0.90 (0.48, 1.68)

0.94 (0.49, 1.78)

No NB-DMARD

447

9852

7.1

Reference

No medication of interest

234

4044

4.5

Oral corticosteroid ≥10 mg/day^d

141

1836

17.4

4.57 (2.79, 7.49)

2.45 (1.32, 4.56)

2.47 (1.32, 4.63)

Oral corticosteroid <10 mg/day^d

177

2610

7.3

1.80 (1.02, 3.19)

1.18 (0.60, 2.30)

1.23 (0.63, 2.41)

No oral corticosteroid

371

7469

4.2

Reference

DMARD

266

5263

6.3

0.90 (0.58, 1.39)

0.89 (0.57, 1.41)

0.88 (0.56, 1.40)

No DMARD

335

6606

7.4

Reference

No medication of interest

232

4074

4.4

Table 4

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Association between exposures after day 139 and preterm birth for RA

Time-dependent medication exposure after gestational day 139^a	n	Preterm birth	Person- weeks	Rate (per 1000/ week)	Crude HR (95% CI)	Adjusted HR^b (95% CI)	Mutually adjusted HR^c (95% CI)
Oral corticosteroid	253	51	4530	11.3	2.81 (1.80, 4.39)	1.64 (0.92, 2.92)	1.83 (1.01, 3.32)
No oral corticosteroid	368	31	7415	4.2	Reference	Reference	Reference
B-DMARD	215	25	4146	6.0	0.90 (0.56, 1.44)	0.91 (0.56, 1.47)	0.85 (0.52, 1.37)
No B-DMARD	389	57	7798	7.3	Reference	Reference	Reference
NB-DMARD	102	12	2092	5.7	0.83 (0.45, 1.53)	0.90 (0.48, 1.68)	0.94 (0.49, 1.78)
No NB-DMARD	447	70	9852	7.1	Reference	Reference	Reference
No medication of interest	234	18	4044	4.5	NA	NA	NA
Oral corticosteroid ≥10 mg/day^d	141	32	1836	17.4	4.57 (2.79, 7.49)	2.45 (1.32, 4.56)	2.47 (1.32, 4.63)
Oral corticosteroid <10 mg/day^d	177	19	2610	7.3	1.80 (1.02, 3.19)	1.18 (0.60, 2.30)	1.23 (0.63, 2.41)
No oral corticosteroid	371	31	7469	4.2	Reference	Reference	Reference
DMARD	266	33	5263	6.3	0.90 (0.58, 1.39)	0.89 (0.57, 1.41)	0.88 (0.56, 1.40)
No DMARD	335	49	6606	7.4	Reference	Reference	Reference
No medication of interest	232	18	4074	4.4	NA	NA	NA

Time-dependent medication exposure after gestational day 139^a	n	Preterm birth	Person- weeks	Rate (per 1000/ week)	Crude HR (95% CI)	Adjusted HR^b (95% CI)	Mutually adjusted HR^c (95% CI)
Oral corticosteroid	253	51	4530	11.3	2.81 (1.80, 4.39)	1.64 (0.92, 2.92)	1.83 (1.01, 3.32)
No oral corticosteroid	368	31	7415	4.2	Reference	Reference	Reference
B-DMARD	215	25	4146	6.0	0.90 (0.56, 1.44)	0.91 (0.56, 1.47)	0.85 (0.52, 1.37)
No B-DMARD	389	57	7798	7.3	Reference	Reference	Reference
NB-DMARD	102	12	2092	5.7	0.83 (0.45, 1.53)	0.90 (0.48, 1.68)	0.94 (0.49, 1.78)
No NB-DMARD	447	70	9852	7.1	Reference	Reference	Reference
No medication of interest	234	18	4044	4.5	NA	NA	NA
Oral corticosteroid ≥10 mg/day^d	141	32	1836	17.4	4.57 (2.79, 7.49)	2.45 (1.32, 4.56)	2.47 (1.32, 4.63)
Oral corticosteroid <10 mg/day^d	177	19	2610	7.3	1.80 (1.02, 3.19)	1.18 (0.60, 2.30)	1.23 (0.63, 2.41)
No oral corticosteroid	371	31	7469	4.2	Reference	Reference	Reference
DMARD	266	33	5263	6.3	0.90 (0.58, 1.39)	0.89 (0.57, 1.41)	0.88 (0.56, 1.40)
No DMARD	335	49	6606	7.4	Reference	Reference	Reference
No medication of interest	232	18	4074	4.4	NA	NA	NA

An additional 30 days of exposure was added to reported end dates of use for oral corticosteroids and DMARDs.

One model for each medication of interest. HR adjusted for quintiles of the propensity score: last menstrual period year (<2009, ≤2009), maternal age, race and ethnicity (Non-Hispanic White, Other), multiple gestation, ≥5 servings of alcohol in the first trimester, autoimmune disease comorbidity (IBD, lupus or ankylosing spondylitis), oral corticosteroid cumulative dose trajectory before gestational day 110 (high, low, none), non-steroidal anti-inflammatory drug before gestational day 110 (any, none) and HAQ Disability Index, pain score and global score at enrolment.

One model, adjusting for each medication exposure group of interest and each associated propensity score.

Prednisone equivalent dose.

B-DMARD, biologic disease modifying antirheumatic drug; HR, hazard ratio; NA, not applicable; NB-DMARD, non-biologic disease-modifying antirheumatic drug.

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