Nausea and Vomiting in Pregnancy in Relation to Prolactin, Estrogens, and Progesterone: a Prospective Study

Objective: To assess pregnancy hormone levels in relation to nausea with or without vomiting.

Methods: In the context of a prospective cohort study, 262 white pregnant women in Boston were observed through delivery. Maternal blood was collected at 16 and 27 weeks' gestation and serum levels of estradiol, estriol, progesterone, prolactin, and sex hormone-binding globulin were determined. Information on sociodemographic and medical variables was collected through an interviewer-administered questionnaire and review of medical records. At the 27th gestational week, nausea with or without vomiting at any time during the index pregnancy was ascertained.

Results: By the 27th gestational week, 209 women (79.8%) had experienced nausea with or without vomiting. There was a substantial and statistically significant (P <.01) inverse association of prolactin with nausea with or without vomiting at both the first and the second samplings, with or without adjustment for the other measured compounds. Estradiol was positively associated with nausea with or without vomiting risk, but the association was evident only after adjustment for the other measured compounds (P values of.06 and.07 at the first and second samplings, respectively). We found no evidence that estriol, progesterone, or sex hormone-binding globulin was related to nausea with or without vomiting at either the 16th or the 27th week of pregnancy.

Conclusion: Our results point to lower levels of prolactin and, perhaps, higher levels of estradiol as contributing to or correlating with the occurrence of nausea with or without vomiting at any time during the pregnancy until the 27th gestational week. We found no evidence that estriol, progesterone, or sex hormone-binding globulin is associated with this condition.