Any birth defect | <4 | 22066 | 1.00 | | 0.47 | 1.00 | | 0.13 |
| 4–24 | 1703 | 1.02 | 0.97 to 1.08 | | 1.06 | 1.01 to 1.12 | |
| >24 | 119 | 0.76 | 0.64 to 0.92 | | 0.92 | 0.77 to 1.11 | |
| | | | | | | | |
All CNS defects | <4 | 1158 | 1.00 | | 0.12 | 1.00 | | 0.36 |
| 4–24 | 95 | 1.09 | 0.88 to 1.34 | | 1.03 | 0.84 to 1.28 | |
| >24 | 13 | 1.60 | 0.93 to 2.77 | | 1.41 | 0.81 to 2.44 | |
| | | | | | | | |
Anencephaly | <4 | 306 | 1.00 | | 0.96 | 1.00 | | 0.55 |
| 4–24 | 21 | 0.91 | 0.58 to 1.42 | | 0.82 | 0.53 to 1.29 | |
| >24 | 3 | 1.40 | 0.45 to 4.36 | | 1.11 | 0.35 to 3.48 | |
| | | | | | | | |
Spina bifida | <4 | 402 | 1.00 | | 0.02 | 1.00 | | 0.04 |
| 4–24 | 38 | 1.25 | 0.90 to 1.75 | | 1.21 | 0.86 to 1.69 | |
| >24 | 7 | 2.48 | 1.18 to 5.25 | | 2.33 | 1.10 to 4.94 | |
| | | | | | | | |
Hydrocephaly | <4 | 310 | 1.00 | | 0.18 | 1.00 | | 0.13 |
| 4–24 | 20 | 0.86 | 0.54 to 1.35 | | 0.82 | 0.52 to 1.30 | |
| >24 | 0 | 0.03 | | 1 | 0.03 | | |
| | | | | | | | |
Other CNS defects | <4 | 147 | 1.00 | | 0.03 | 1.00 | | 0.05 |
| 4–24 | 16 | 1.44 | 0.86 to 2.42 | | 1.44 | 0.86 to 2.43 | |
| >24 | 3 | 2.91 | 0.93 to 9.13 | | 2.55 | 0.81 to 8.06 | |
| | | | | | | | |
Cardiac defects | <4 | 1744 | 1.00 | | 0.03 | 1.00 | | 0.33 |
| 4–24 | 118 | 0.90 | 0.74 to 1.08 | | 1.00 | 0.83 to 1.21 | |
| >24 | 4 | 0.33 | 0.12 to 0.87 | | 0.40 | 0.15 to 1.05 | |
| | | | | | | | |
Respiratory system defects | <4 | 490 | 1.00 | | 0.02 | 1.00 | | 0.05 |
| 4–24 | 24 | 0.65 | 0.43 to 0.98 | | 0.90 | 0.59 to 1.36 | |
| >24 | 1 | 0.30 | 0.04 to 2.07 | | 0.50 | 0.07 to 3.59 | |
| | | | | | | | |
Isolated cleft palate | <4 | 397 | 1.00 | | 0.01 | 1.00 | | 0.01 |
| 4–24 | 17 | 0.57 | 0.35 to 0.93 | | 0.57 | 0.35 to 0.92 | |
| >24 | 1 | 0.37 | 0.05 to 2.56 | | 0.34 | 0.05 to 2.34 | |
| | | | | | | | |
Total cleft lip | <4 | 1042 | 1.00 | | 0.10 | 1.00 | | 0.12 |
| 4–24 | 85 | 1.08 | 0.87 to 1.35 | | 1.07 | 0.86 to 1.34 | |
| >24 | 13 | 1.78 | 1.03 to 3.08 | | 1.73 | 1.00 to 2.99 | |
| | | | | | | | |
Genital system defects | <4 | 3208 | 1.00 | | 0.56 | 1.00 | | 0.19 |
| 4–24 | 273 | 1.13 | 1.00 to 1.28 | | 1.15 | 1.02 to 1.31 | |
| >24 | 13 | 0.58 | 0.34 to 1.00 | | 0.71 | 0.41 to 1.22 | |
| | | | | | | | |
Clubfoot | <4 | 5051 | 1.00 | | 0.02 | 1.00 | | 0.04 |
| 4–24 | 460 | 1.21 | 1.10 to 1.33 | | 1.13 | 1.03 to 1.25 | |
| >24 | 24 | 0.68 | 0.45 to 1.01 | | 0.92 | 0.62 to 1.38 | |
| | | | | | | | |
Other defects‡ | <4 | 58 | 1.00 | | 0.63 | 1.00 | | 0.45 |
| 4–24 | 4 | 0.91 | 0.33 to 2.52 | | 0.76 | 0.27 to 2.11 | |
| >24 | 0 | 0.07 | | | 0.03 | | |
| | | | | | | | |
Down's syndrome | <4 | 871 | 1.00 | | 0.02 | 1.00 | | 0.29 |
| 4–24 | 51 | 0.78 | 0.59 to 1.03 | | 0.93 | 0.70 to 1.24 | |
| >24 | 2 | 0.33 | 0.08 to 1.31 | | 0.43 | 0.11 to 1.70 | |