Table 2.
Cumulative prevalence of birth defects according to age at diagnosis and plurality.
| Age at diagnosis | ART-conceived | Spontaneous-conceived | Crude RR (95%CI) | aRR (95%CI)a | ||
|---|---|---|---|---|---|---|
| No. of birth | No. of birth defects (%) | No. of birth | No. of birth defects (%) | |||
| All Births | ||||||
| Prenatal | 2231 | 50 (2•2) | 3433 | 42 (1•2) | 1•89 (1•24–2•86) | 2•10 (1•23–3•59) |
| By 7 days after delivery | 2231 | 109 (4•9) | 3433 | 100 (2•9) | 1•74 (1•31–2•31) | 1•63 (1•16–2•28) |
| By 6 months after delivery | 1921 | 200 (10•4) | 3118 | 164 (5•3) | 2•09 (1•67–2•62) | 1•95 (1•50–2•54) |
| By 1 year after delivery | 1566 | 217 (13•9) | 2768 | 194 (7•0) | 2•17 (1•75–2•69) | 1•99 (1•55–2•56) |
| Singleton Births | ||||||
| Prenatal | 1349 | 42 (3•1) | 3367 | 40 (1•2) | 2•74 (1•77–4•25) | 2•97 (1•67–5•29) |
| By 7 days after delivery | 1349 | 73 (5•4) | 3367 | 95 (2•8) | 1•99 (1•46–2•72) | 1•82 (1•25–2•65) |
| By 6 months after delivery | 1118 | 107 (9•6) | 3059 | 153 (5•0) | 2•02 (1•56–2•61) | 1•88 (1•38–2•55) |
| By 1 year after delivery | 873 | 112 (12•8) | 2713 | 182 (6•7) | 2•05 (1•60–2•63) | 1•85 (1•38–2•48) |
| Twins | ||||||
| Prenatal | 882 | 8 (0•9) | 66 | 2 (3•0) | 0•29 (0•06–1•43) | 0•24 (0•06–1•03) |
| By 7 days after delivery | 882 | 36 (4•1) | 66 | 5 (7•6) | 0•52 (0•17–1•60) | 0•50 (0•13–1•92) |
| By 6 months after delivery | 803 | 93 (11•6) | 59 | 11 (18•6) | 0•56 (0•24–1•29) | 0•45 (0•18–1•10) |
| By 1 year after delivery | 693 | 105 (15•2) | 55 | 12 (21•8) | 0•64 (0•28–1•50) | 0•51 (0•20–1•31) |
a Analyses were adjusted for maternal age, parity, maternal pre-pregnancy BMI, diabetes and hypertension.