Table 2.
Risk of hyperemesis in female partners of sons and unadjusted odds ratio for hyperemesis with 95% confidence interval depending on occurrence of hyperemesis in man’s mother, medical birth registry of Norway 1967-2006
| Hyperemesis in mother | No of pregnancies | No of female partners with hyperemesis | Risk of hyperemesis in female partners (%) | OR* (95% CI) |
|---|---|---|---|---|
| All mother-child producing son units | ||||
| Yes | 2290 | 27 | 1.18 | 1.04 (0.68 to 1.58) |
| No | 397 487 | 4499 | 1.13 | Reference |
| Total | 399 777 | 4526 | 1.13 | — |
| Restriction to firstborn in both generations | ||||
| Yes | 569 | 7 | 1.23 | 1.15 (0.54 to 2.43) |
| No | 83 822 | 896 | 1.07 | Reference |
| Total | 84 391 | 903 | 1.07 | — |
*OR=odds ratio based on robust clustering accounting for dependencies within data. Of first generation mothers, 54% contribute to more than one family record. Adjustment for maternal age at childbirth and period of birth in both generations and maternal parity in first generation (when not restricted to first birth order) did not change estimates.