Does greater morning sickness predict carrying a girl? Analysis of nausea and vomiting during pregnancy from retrospective report.

PURPOSE: The prevalence of severe nausea and vomiting during pregnancy (NVP) requiring hospitalization has been associated with female fetal sex. However, the question of whether fetal sex and less severe forms of NVP share that association has not been investigated. The objective of this study was to evaluate the relationship between fetal sex and the frequency of NVP.

METHODS

We collected self-reported data from mothers via an international web-based survey on the Amazon Mechanical Turk (MTurk) platform about pregnancy and first trimester NVP history. We considered the covariables of maternal age, parity status, proneness to nausea, geographic cohort, and preconceived notions of a relationship between fetal sex and NVP.

RESULTS

Two-thousand five hundred and forty-three mothers met the inclusion criteria, yielding data from 4320 pregnancies. Women gestating a female fetus reported higher frequencies of NVP (M = 6.35 on a 1-9 scale) than did women gestating males (M = 6.04, p = .007). This effect held true when all other variables were included in the regression. General proneness to nausea, maternal age, and parity were also significant independent predictors of NVP.

CONCLUSIONS

Women that carried a female fetus, as opposed to a male fetus, reported significantly higher frequency of NVP during the first trimester of pregnancy. Further research should evaluate both the proximate and ultimate causes of this relationship.