Table 2:
Risk factors associated with isolated orofacial clefts among 832 636 live births in univariable analysis
| Risk factor | N | n (prevalence per 1000 births) | OR (95% CI) | p value* |
|---|---|---|---|---|
| Cleft lip with or without cleft palate | ||||
| Year of birth | ||||
| 1996–1998 | 199 863 | 233 (1.17) | 1.00 | |
| 1999–2001 | 197 823 | 218 (1.10) | 0.95 (0.79–1.14) | |
| 2002–2004 | 192 674 | 215 (1.11) | 0.96 (0.80–1.15) | |
| 2005–2008 | 242 276 | 209 (0.09) | 0.74 (0.61–0.89) | 0.006 |
| Maternal residence at start of pregnancy† | ||||
| Capital region | 268 558 | 272 (1.01) | 1.00 | |
| Sealand | 106 128 | 141 (1.33) | 1.31 (1.07–1.61) | |
| Southern Denmark | 172 595 | 181 (1.05) | 1.04 (0.86–1.25) | |
| Middle Jutland | 190 832 | 202 (1.06) | 1.05 (0.87–1.25) | |
| Northern Jutland | 82 736 | 71 (0.86) | 0.85 (0.65–1.10) | 0.030 |
| Maternal place of origin‡ | ||||
| Denmark | 713 522 | 779 (1.09) | 1.00 | |
| Europe and North America | 41 858 | 42 (1.00) | 0.92 (0.67–1.25) | |
| Rest of the world | 73 876 | 52 (0.70) | 0.64 (0.49–0.85) | 0.004 |
| Smoking status during pregnancy§ | ||||
| Did not smoke | 642 283 | 648 (1.01) | 1.00 | |
| Did smoke | 161 498 | 198 (1.23) | 1.22 (1.04–1.43) | 0.018 |
| History of orofacial clefts among offspring | ||||
| No | 831 214 | 864 (1.04) | 1.00 | |
| Yes | 1 422 | 11 (7.74) | 7.49 (4.12–13.61) | < 0.001 |
| History of birth defects among offspring | ||||
| No | 795 984 | 819 (1.03) | 1.00 | |
| Yes | 36 652 | 56 (1.53) | 1.37 (1.04–1.79) | 0.030 |
| Cleft palate alone | ||||
| Year of birth | ||||
| 1996–1998 | 199 863 | 104 (0.52) | 1.00 | |
| 1999–2001 | 197 823 | 84 (0.42) | 0.82 (0.61–1.09) | |
| 2002–2004 | 192 674 | 88 (0.46) | 0.88 (0.66–1.17) | |
| 2005–2008 | 242 276 | 81 (0.33) | 0.64 (0.48–0.86) | 0.024 |
| Maternal residence at start of pregnancy† | ||||
| Capital region | 268 558 | 91 (0.34) | 1.00 | |
| Sealand | 106 128 | 62 (0.58) | 1.72 (1.25–2.38) | |
| Southern Denmark | 172 595 | 97 (0.56) | 1.66 (1.25–2.21) | |
| Middle Jutland | 190 832 | 70 (0.37) | 1.08 (0.79–1.48) | |
| Northern Jutland | 82 736 | 33 (0.40) | 1.18 (0.79–1.75) | < 0.001 |
| History of orofacial clefts in offspring | ||||
| No | 831 214 | 352 (0.42) | 1.00 | < 0.001 |
| Yes | 1 422 | 5 (3.52) | 8.33 (3.44–20.17) | |
Note: CI = confidence interval, OR = odds ratio.
*
Likelihood ratio test.
†
Women whose place of residence was not known (1.4%) were excluded from the analysis.
‡
Women whose country of origin was not known (0.4%) were excluded from the analysis.
§
Women for whom smoking status was not known (3.5%) were excluded from the analysis.