Maternal characteristics at the time of childbirth (n=1000)
| Controls (n=564) | Anti-TNF-α monotherapy (n=136) | P value | Thiopurine monotherapy (n=240) | P value | Anti-TNF-α and thiopurine (n=60) | P value | |
| Median maternal age at birth (IQR) | 32 (29–35) | 30 (28–33) | <0.01 | 32 (29–35) | 0.26 | 32 (30–34) | 0.38 |
| Education level (%) | |||||||
| High | 270 (51) | 54 (45) | 0.27 | 111 (50) | 0.75 | 31 (53) | 0.68 |
| Secondary | 225 (43) | 57 (48) | 0.36 | 95 (42) | 1 | 24 (43) | 1 |
| Low | 34 (6) | 9 (7) | 0.69 | 18 (8) | 0.43 | 2 (4) | 0.56 |
| Diagnosis (%) | |||||||
| Crohn’s disease | 289 (51) | 112 (82) | <0.01 | 170 (71) | <0.01 | 42 (70) | <0.01 |
| Ulcerative colitis | 252 (45) | 22 (16) | <0.01 | 66 (27) | <0.01 | 15 (25) | <0.01 |
| IBD unclassified | 23 (4) | 2 (2) | 0.2 | 5 (2) | 0.21 | 3 (5) | 0.73 |
| Disease location CD (montreal) (%) | |||||||
| L1 Ileal | 43 (15) | 15 (14) | 0.87 | 20 (12) | 0.33 | 7 (18) | 0.64 |
| L2 Colonic | 73 (26) | 23 (22) | 0.43 | 40 (24) | 0.66 | 7 (18) | 0.33 |
| L3 Ileocolonic | 170 (59) | 69 (64) | 0.42 | 111 (64) | 0.28 | 26 (64) | 0.61 |
| Disease behaviour CD (montreal) (%) | |||||||
| B1 non-stricturing non penetrating | 136 (50) | 61 (56) | 0.37 | 78 (47) | 0.43 | 16 (40) | 0.24 |
| B2 stricturing | 48 (18) | 9 (8) | 0.02 | 27 (16) | 0.7 | 3 (8) | 0.11 |
| B3 penetrating | 47 (18) | 20 (18) | 0.88 | 40 (25) | 0.11 | 15 (37) | <0.01 |
| B2 + B3 stricturing and penetrating | 37 (14) | 19 (17) | 0.43 | 22 (12) | 0.89 | 6 (15) | 0.81 |
| Perianal fistulising disease CD (%) | 67 (24) | 35 (32) | 0.13 | 41 (24) | 0.91 | 21 (54) | <0.01 |
| Disease extent UC/IBDU (montreal) (%) | |||||||
| E1 proctitis | 86 (34) | 2 (9) | 0.02 | 15 (23) | 0.1 | 2 (12) | 0.1 |
| E2 left-sided colitis | 69 (27) | 6 (26) | 1 | 24 (37) | 0.17 | 3 (19) | 0.57 |
| E3 pancolitis | 99 (39) | 15 (65) | 0.03 | 27 (40) | 0.78 | 11 (69) | 0.03 |
| Disease duration in years (IQR) | 8 (5–13) | 9 (5–12) | 0.77 | 7 (5–12) | 0.05 | 8 (5–12) | 0.34 |
| Concomitant IBD medication use (%) | |||||||
| Systemic steroid (alone or in combination with 5-ASA) | 79 (14) | 24 (18) | 0.28 | 46 (19) | 0.07 | 6 (10) | 0.55 |
| 5-ASA (no steroids) | 256 (45) | 6 (4) | <0.01 | 55 (23) | <0.01 | 8 (13) | <0.01 |
| No concomitant IBD medication | 229 (41) | 106 (78) | <0.01 | 139 (58) | <0.01 | 46 (77) | <0.01 |
| IBD abdominal surgery prior to pregnancy (%) | 145 (26) | 36 (27) | 0.91 | 58 (24) | 0.66 | 10 (17) | 0.16 |
| Nulliparous (%) | 275 (49) | 77 (57) | 0.08 | 132 (55) | 0.11 | 33 (56) | 0.34 |
| Folic acid intake (%) | 506 (94) | 123 (99) | 0.01 | 209 (91) | 0.16 | 49 (93) | 0.56 |
Study groups were compared with the controls. The Bonferroni correction was applied to adjust for multiple testing. A statistically significant difference was defined as a P<0.02.
5-ASA, 5-aminosalicylic acid; CD, Crohn’s disease; IBD, inflammatory bowel disease; IBDU, inflammatory bowel disease unclassified; IQR, interquartile range; TNF, tumour necrosis factor; UC, ulcerative colitis.