14.   GENETIC FACTORS IN RELATION TO NVP

1. NVP is more than twice more common in women who have monozygotic (one egg) twins than in women who have dizygotic (two egg) twins, which suggests there is a maternal genetic factor responsible for NVP. Information from 2,655 twin pairs who each had a pregnancy. This included 830 monozygotic female, 902 dizygotic female, 459 monozygotic male and 464 dizygotic male twin pairs.  (47)
2. There was an association between the women in our clinic suffering nausea and vomiting and their mother having experienced pregnancy sickness (P>0.0001). 343 out of 518 said their mother was sick. (40)
3. Women whose mothers had trouble with NVP were significantly more likely to have NVP themselves (P>0.001). 363 women in study population. (53)
4. 202 of the women studied whose sisters who had themselves been pregnant. The results show that women whose sisters had been nauseous in pregnancy were statistically more likely to be so themselves (P
5. Whether mothers of the study subjects had had nausea during pregnancy was not related to the study subjects’ current experience with nausea and to their scores in the overall nausea index. 160 women in study. (80)
6. Different partners have no impact on NVP. Paternal contribution to placental function does not affect NVP. (142)
7. 28% (348/1224) of participants reported that their mother had experienced severe NVP or HG while pregnant with them. A strong family history of HG (two or more affected relatives) was reported by 109/1224 (9%). 1224 women who completed an online survey administered by the Hyperemesis Education and Research (HER) Foundation www.helpher.org between 2003 – 2006. (152)
8. 504 participants reported on the pregnancy history of 721 sisters prevalence of HG (HG specifically mentioned) was 19% 137/721 affected sisters. (152)
9. The risk of hyperemesis for a pregnant woman is three-fold if the woman’s mother had ever experienced hyperemesis in a pregnancy. (157)
   HG is more strongly influenced by the maternal genotype than fetal genotype, though environmental influences along the maternal line cannot be excluded as contributing factors. (157)

Summary

Women whose mother suffered from NVP more likely to have NVP themselves.

(27) t (40) t (53) t                                                                                      Total:            Three References

Women whose sisters had NVP more likely to have NVP.

(27)                                                                                                            Total:            One Reference

Maternal genetic factor responsible for NVP. (47) (53) (152)(157)            Total:            Four References

Mothers’ NVP not related to study subjects’ experience of NVP. (80)

                                                                                                                     Total:            One Reference

Paternal contribution does not affect NVP. (142)                                         Total:            One Reference

tP value recorded.