Is lack of morning sickness teratogenic? a prospective controlled study

Case control studies have suggested that nausea and vomiting of pregnancy (NVP) has a protective effect against specific malformations. These suggestions have been interpreted as if lack of NVP may put mothers at an increased teratogenic risk. Objective To evaluate whether lack of NVP increases the overall rates for major malformations. Method A prospective, cohort controlled study comparing pregnancy outcome in women not experiencing NVP with those experiencing NVP at two levels of severity. Women who called the Motherisk program about first trimester exposure to drugs but without NVP were included. The NVP Healthline enrolled two groups of women with NVP exposed to doxylamine‐pyridoxine (DiclectinÒ) for morning sickness. These women were exposed during first trimester of gestation to either higher than standard dose (5–12tbl/day) or a standard dose (1–4 tbl/day) of Diclectin. The women were followed up 4–6 months after of the expected date of birth to ascertain pregnancy outcome. Results There were no major malformations among offspring of 130 women not experiencing NVP. There were two major malformations among 246 women experiencing NVP. The two groups were of similar distribution of gestational ages, birth rates, as well as rates of miscarriages and stillbirths. Conclusions Lack of NVP does not effect the overall rates of major malformations. The results of retrospective, case control studies should not be used to alarm women about such risk. Clinical Pharmacology & Therapeutics (2004) 75 , P73–P73; doi: 10.1016/j.clpt.2003.11.274