Table 5.
Interaction between multiplicity and mode of conception in the risk of birth defects.
| Crude OR | 95% CI | P value | Adjusted OR* | 95% CI | P value | |||
|---|---|---|---|---|---|---|---|---|
| Multiplicity | ||||||||
| Singleton | 1.00 | 1.00 | ||||||
| Twins | 8.19 | 6.12 | 10.95 | <0.001 | 8.00 | 5.78 | 11.07 | <0.001 |
| Triplets | 31.49 | 11.72 | 84.64 | <0.001 | 27.70 | 10.28 | 74.58 | <0.001 |
| Mode of conception | ||||||||
| Spontaneous conception | 1.00 | 1.00 | ||||||
| Assisted conception | 2.77 | 1.96 | 3.92 | <0.001 | 2.33 | 1.63 | 3.32 | <0.001 |
| Interaction term (ART × multiplicity) | ||||||||
| Spontaneous conception × singleton | 1.00 | 1.00 | ||||||
| ART × twins | 0.53 | 0.31 | 0.90 | 0.020 | 0.54 | 0.32 | 0.92 | 0.024 |
| ART × triplets | 0.88 | 0.15 | 4.96 | 0.880 | 1.04 | 0.18 | 5.91 | 0.963 |
*Analyses were adjusted for maternal age at delivery (≤24, 25–34, and ≥35), residence (Shanghai, other provinces), gravidity (number), history of abnormal pregnancy (yes and no), parity (nulliparous and pluripara), birth weight (g) and year, maternal disease in pregnancy (pre-existing hypertension and diabetes, gestational hypertension, gestational diabetes mellitus, or anaemia) and foetal gender in Cox regression models.