Table 2.
Adjusted ORs and 95% CIs for associations between twinning and birth defects, stratified by use of fertility treatment, National Birth Defects Prevention Study, 1997–2007
| Type of birth defect† | Total | Any use of fertility treatment | No fertility treatment used | ||||||
|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|||||||
| Plurality | Adjusted OR‡ (95% CI)* | Plurality | Adjusted OR‡ (95% CI) | Plurality | Adjusted OR‡ (95% CI) | ||||
|
|
|
|
|||||||
| Twin (n) | Singleton (n) | Twin (n) | Singleton (n) | Twin (n) | Singleton (n) | ||||
| Controls | 218 | 7654 | Ref. | 71 | 246 | Ref. | 147 | 7408 | Ref. |
| Central nervous system | |||||||||
| Anencephaly | 21 | 381 | 2.2 (1.4 to 3.4) | 4 | 14 | NC | 17 | 367 | 2.5 (1.5 to 4.2) |
| Spina bifida | 27 | 820 | 1.2 (0.8 to 1.8) | 8 | 29 | 1.0 (0.5 to 2.4) | 19 | 791 | 1.2 (0.7 to 2.0) |
| Encephalocele | 5 | 147 | 1.3 (0.5 to 3.2) | 0 | 8 | NC | 5 | 139 | 1.9 (0.8 to 4.7) |
| Holoprosencephaly | 7 | 106 | 2.7 (1.2 to 5.8) | 2 | 7 | NC | 5 | 99 | 2.5 (1.0 to 6.3) |
| Hydrocephalus | 26 | 329 | 2.9 (1.9 to 4.4) | 0 | 12 | NC | 26 | 317 | 4.2 (2.8 to 6.6) |
| Dandy Walker malformation | 8 | 108 | 2.8 (1.3 to 5.8) | 2 | 4 | NC | 6 | 104 | 3.0 (1.3 to 7.0) |
| Eye | |||||||||
| Cataracts and other lens defects | 10 | 230 | 1.6 (0.8 to 3.0) | 3 | 8 | 1.5 (0.4 to 5.9) | 7 | 223 | 1.7 (0.8 to 3.8) |
| Glaucoma | 5 | 119 | 1.6 (0.6 to 3.9) | 2 | 2 | NC | 3 | 117 | NC |
| Anotia/microtia | 20 | 418 | 1.8 (1.1 to 3.0) | 10 | 16 | 2.4 (1.0 to 5.6) | 10 | 402 | 1.2 (0.6 to 2.3) |
| Cardiovascular | |||||||||
| Heterotaxia | 6 | 291 | 1.3 (0.6 to 2.9) | 0 | 8 | NC | 6 | 283 | 0.9 (0.4 to 2.2) |
| Dextro-transposition of great arteries | 21 | 534 | 1.4 (0.9 to 2.1) | 7 | 19 | 1.3 (0.5 to 3.1) | 14 | 515 | 1.4 (0.8 to 2.4) |
| Tetralogy of Fallot | 53 | 772 | 2.3 (1.7 to 3.1) | 11 | 44 | 0.9 (0.4 to 1.7) | 42 | 728 | 2.9 (2.0 to 4.1) |
| Atrioventricular septal defects | 9 | 238 | 1.3 (0.6 to 2.5) | 1 | 12 | NC | 8 | 226 | 1.8 (0.9 to 3.6) |
| Total anomalous pulmonary venous return | 8 | 196 | 1.5 (0.8 to 3.2) | 2 | 5 | NC | 6 | 191 | 1.6 (0.7 to 3.6) |
| Perimembranous ventricular septal defect | 108 | 1320 | 2.8 (2.2 to 3.6) | 33 | 58 | 2.0 (1.2 to 3.3) | 75 | 1262 | 3.0 (2.3 to 4.0) |
| Conoventricular septal defect | 11 | 107 | 3.2 (1.7 to 6.2) | 3 | 3 | NC | 8 | 104 | 3.8 (1.8 to 8.1) |
| Multiple ventricular septal defects | 13 | 52 | 9.2 (4.9 to 17.4) | 5 | 2 | NC | 8 | 50 | 8.5 (3.9 to 18.3) |
| Secundum atrial septal defect | 142 | 1557 | 3.4 (2.7 to 4.2) | 37 | 59 | 2.4 (1.4 to 3.9) | 105 | 1498 | 3.6 (2.8 to 4.7) |
| Atrial septal defect, not otherwise specified | 9 | 238 | 2.4 (1.6 to 3.5) | 10 | 19 | 1.9 (0.9 to 4.4) | 23 | 465 | 2.3 (1.5 to 3.7) |
| Tricuspid atresia | 10 | 109 | 3.2 (1.7 to 6.3) | 4 | 1 | NC | 6 | 108 | 2.7 (1.2 to 6.3) |
| Pulmonary valve stenosis | 84 | 937 | 3.0 (2.3 to 3.9) | 16 | 36 | 1.6 (0.8 to 3.0) | 68 | 901 | 3.6 (2.7 to 4.9) |
| Pulmonary atresia | 16 | 163 | 3.5 (2.1 to 6.0) | 3 | 4 | NC | 13 | 159 | 4.1 (2.3 to 7.5) |
| Coarctation of the aorta | 54 | 716 | 2.5 (1.8 to 3.4) | 15 | 37 | 1.4 (0.7 to 2.7) | 39 | 679 | 2.8 (2.0 to 4.1) |
| Aortic stenosis | 21 | 309 | 2.2 (1.4 to 3.5) | 5 | 17 | 1.0 (0.4 to 2.8) | 16 | 292 | 2.8 (1.6 to 4.7) |
| Hypoplastic left heart syndrome | 25 | 413 | 2.1 (1.4 to 3.3) | 10 | 13 | 2.8 (1.2 to 6.7) | 15 | 400 | 1.9 (1.1 to 3.2) |
| Single ventricle | 9 | 239 | 1.3 (0.7 to 2.6) | 0 | 3 | NC | 9 | 236 | 1.9 (0.9 to 3.7) |
| Coarctation of aorta with ventricular septal defect | 15 | 195 | 2.7 (1.5 to 4.6) | 3 | 11 | NC | 12 | 184 | 3.3 (1.8 to 6.0) |
| Pulmonary valve stenosis with atrial septal defect | 15 | 142 | 3.8 (2.2 to 6.6) | 3 | 2 | NC | 12 | 140 | 4.0 (2.2 to 7.5) |
| Pulmonary valve stenosis with ventricular septal defect | 6 | 107 | 2.0 (0.9 to 4.7) | 2 | 2 | NC | 4 | 105 | NC |
| Atrial septal defect with ventricular septal defect | 39 | 540 | 2.4 (1.7 to 3.4) | 8 | 24 | 1.1 (0.5 to 2.7) | 31 | 516 | 3.0 (2.0 to 4.5) |
| Orofacial | |||||||||
| Cleft lip±cleft palate | 101 | 2020 | 1.8 (1.4 to 2.4) | 30 | 80 | 1.4 (0.8 to 2.2) | 71 | 1940 | 1.9 (1.4 to 2.5) |
| Cleft palate | 44 | 1087 | 1.4 (1.0 to 1.9) | 14 | 55 | 0.9 (0.5 to 1.6) | 30 | 1032 | 1.4 (1.0 to 2.1) |
| Choanal atresia | 8 | 101 | 2.3 (1.1 to 4.9) | 4 | 7 | NC | 4 | 94 | NC |
| Gastrointestinal | |||||||||
| Duodenal atresia | 5 | 140 | 1.2 (0.5 to 3.1) | 3 | 8 | NC | 2 | 132 | NC |
| Oesophageal atresia with/without tracheoesophageal fistula | 53 | 444 | 3.6 (2.6 to 5.0) | 20 | 40 | 1.6 (0.9 to 2.9) | 33 | 404 | 4.2 (2.8 to 6.2) |
| Biliary atresia | 7 | 124 | 2.0 (0.9 to 4.4) | 0 | 7 | NC | 7 | 117 | 3.0 (1.4 to 6.6) |
| Small intestinal atresia | 22 | 301 | 2.7 (1.7 to 4.3) | 3 | 8 | NC | 19 | 293 | 3.2 (2.0 to 5.3) |
| Anorectal atresia | 49 | 681 | 2.6 (1.9 to 3.5) | 15 | 28 | 1.9 (1.0 to 3.8) | 34 | 653 | 2.6 (1.8 to 3.9) |
| Genitourinary | |||||||||
| Renal agenesis/hypoplasia | 5 | 112 | 1.7 (0.7 to 4.2) | 0 | 2 | NC | 5 | 110 | 2.2 (0.9 to 5.6) |
| Hypospadias§ | 113 | 1480 | 2.2 (1.7 to 2.9) | 53 | 100 | 1.6 (1.0 to 2.7) | 60 | 1380 | 2.3 (1.6 to 3.2) |
| Musculoskeletal | |||||||||
| Cloacal exstrophy | 7 | 54 | 4.9 (2.2 to 10.9) | 1 | 8 | NC | 6 | 46 | 6.5 (2.7 to 15.5) |
| Intercalary limb deficiency | 6 | 42 | 5.2 (2.1 to 12.4) | 3 | 3 | NC | 3 | 39 | NC |
| Longitudinal limb deficiency | 21 | 304 | 2.6 (1.6 to 4.1) | 8 | 14 | 2.1 (0.8 to 5.1) | 13 | 290 | 2.4 (1.3 to 4.3) |
| Preaxial limb deficiency | 14 | 186 | 2.9 (1.7 to 5.1) | 7 | 10 | 2.7 (1.0 to 7.3) | 7 | 176 | 2.1 (1.0 to 4.7) |
| Transverse limb deficiency | 26 | 465 | 2.0 (1.3 to 3.0) | 7 | 21 | 1.2 (0.5 to 2.9) | 19 | 444 | 2.2 (1.3 to 3.6) |
| Craniosynostosis | 50 | 962 | 1.7 (1.2 to 2.3) | 24 | 51 | 1.6 (0.9 to 2.8) | 26 | 911 | 1.4 (0.9 to 2.1) |
| Diaphragmatic hernia | 25 | 566 | 1.5 (1.0 to 2.3) | 10 | 19 | 1.8 (0.8 to 4.0) | 15 | 547 | 1.4 (0.8 to 2.4) |
| Omphalocele | 26 | 290 | 3.0 (1.9 to 4.6) | 10 | 12 | 2.8 (1.2 to 6.9) | 16 | 278 | 3.0 (1.7 to 5.0) |
| Gastroschisis | 19 | 898 | 1.1 (0.7 to 1.9) | 0 | 5 | NC | 19 | 893 | 1.3 (0.8 to 2.2) |
| Amniotic band sequence | 23 | 221 | 3.7 (2.3 to 5.7) | 4 | 7 | NC | 19 | 214 | 5.3 (3.2 to 8.8) |
*
Bold values indicate p<0.05.
†
Includes isolated and multiple defects.
‡
Adjusted for maternal age at delivery (continuous), race, parity, obesity, education, smoking, use of a folic acid-containing multivitamins and study site.
§
Controls limited to male infants.
NC, not calculated because ≤4 twin pregnancies.