The effectiveness of discontinuing iron-containing prenatal multivitamins on reducing the severity of nausea and vomiting of pregnancy

Nausea and vomiting of pregnancy (NVP) is experienced by the majority of pregnant women, and can negatively affect a women's quality of life. It has been suggested in observational studies that iron-containing prenatal multivitamins may increase the severity of NVP. The objective of this study was to determine whether decreasing iron exposure can mitigate NVP symptoms. Data were collected from a prospective cohort at the Motherisk Program in Toronto. Women (n = 97) seeking advice on managing severe NVP were advised to discontinue prenatal multivitamin administration and switch to folic acid, an adult multivitamin or a children's chewable multivitamin. Two-thirds (63 out of 97) (p < 0.001) of those women qualitatively reported an improvement in NVP symptoms after discontinuation of iron-containing prenatal multivitamins. These findings were verified quantitatively using both the pregnancy-unique quantification of emesis and nausea (PUQE) (p < 0.001) and well-being (p < 0.001) scoring systems. This is the first interventional study showing that discontinuation of iron results in improvement of NVP symptoms. Our data suggest that avoiding iron-containing prenatal multivitamins in the first trimester is effective in improving NVP symptoms in the majority of pregnant women suffering from morning sickness.