Table 1.
Maternal characteristics. Metformin study from European Teratology Information Services (TIS) 1993–2015
| Characteristics | Metformin group (n = 458) | Reference group (n = 479) | ||
|---|---|---|---|---|
| Maternal age (yr) median (IQR) | 35 | (31–39) | 35 | (31–38) |
| Body mass index (BMI) n (%) | ||||
| Missing | 226 | (49) | 310 | (65) |
| BMI ≤ 30 | 126 | (28) | 152 | (32) |
| BMI > 30 | 106 | (23) | 17 | (4) |
| Comorbidities and co‐medication n (%) | ||||
| ≥ 1 comorbidities (except diabetes) | 178 | (39) | 114 | (24) |
| Pre‐gestational diabetes | 261 | (57) | 2 | (0.4) |
| Hypertension | 60 | (13) | 8 | (2) |
| Psychiatric disorders | 20 | (4) | 34 | (7) |
| Polycystic ovary syndrome | 25 | (5) | 1 | (0.2) |
| Hyperlipidaemia | 21 | (5) | 2 | (0.4) |
| Any concomitant medication | 352 | (77) | 212 | (44) |
| Other oral antidiabetic drugs | 106 | (23) | 0 | (0) |
| Insulin | 123 | (27) | 0 | (0) |
| Gestational age at first contact | ||||
| Median (IQR) [wk] | 9 | (6–13.5) | 8 | (6–14) |
| Smoking n (%) | ||||
| Missing | 124 | (27) | 142 | (30) |
| No | 285 | (62) | 298 | (62) |
| ≤5 cigarettes/day | 11 | (2) | 16 | (3) |
| >5 cigarettes/day | 38 | (8) | 23 | (5) |
| Alcohol n (%) | ||||
| Missing | 146 | (32) | 167 | (34) |
| <1 drink/day | 295 | (64) | 285 | (60) |
| ≥1 drink/day | 17 | (4) | 27 | (6) |
| Folic acid n (%) | ||||
| Missing | 230 | (50) | 259 | (54) |
| Yes | 173 | (38) | 198 | (41) |
| No | 55 | (12) | 22 | (5) |
| Previous pregnancies and deliveries n (%) | ||||
| Missing | 33 | (7) | 41 | (9) |
| Primigravida | 119 | (26) | 167 | (35) |
| Primiparous | 115 | (25) | 116 | (24) |
| Multiparous | 154 | (33) | 104 | (22) |
| Previous SABs n (%) | ||||
| Missing | 70 | (15) | 92 | (19) |
| 0 | 287 | (63) | 313 | (65) |
| 1 | 64 | (14) | 57 | (12) |
| ≥2 | 37 | (8) | 17 | (4) |
| Previous children with birth defects n (%) | ||||
| Missing | 228 | (50) | 243 | (51) |
| Yes | 11 | (2) | 9 | (2) |
| No | 219 | (48) | 227 | (47) |
IQR, interquartile range; SAB, spontaneous abortion