Maternal human chorionic gonadotrophin concentrations in very early pregnancy and risk of hyperemesis gravidarum: A retrospective cohort study of 4372 pregnancies after in vitro fertilization

Abstract

Objective We investigated the association of human chorionic gonadotrophin (hCG) concentrations on a fixed day in very early pregnancy with development of hyperemesis gravidarum.

Study design This retrospective cohort study included 3107 singleton and 1265 twin pregnancies after in vitro fertilization treated at Department of Reproductive Medicine, Rikshospitalet, Oslo University Hospital, Norway in the period 1996–2013. Maternal serum hCG concentrations was measured on day 12 after embryo transfer. Information about development of hyperemesis gravidarum was obtained by individual linkage to the Medical Birth Registry of Norway. We studied hCG concentrations in very early pregnancy according to development of hyperemesis gravidarum, in singleton and twin pregnancies separately. We estimated the odds ratios for hyperemesis gravidarum with 95% confidence intervals according to quartiles of hCG concentrations.

Results In twin pregnancies as compared to singleton pregnancies, we found higher mean maternal hCG concentrations (219 IU/L versus 130 IU/L, p < 0.001 Student’s t-test) and higher prevalence of hyperemesis gravidarum (2.7% versus 1.4%, p = 0.002 chi-squared test). However, both in singleton and in twin pregnancies, we found no significant difference in mean hCG concentrations between women who developed hyperemesis gravidarum and women who did not (Singletons: 122 IU/L versus 130 IU/L, p = 0.504. Twins: 234 IU/L versus 219 IU/L, p = 0.417 Student’s t-test). We found no significant differences in odds ratios for developing hyperemesis gravidarum according to quartiles of hCG concentrations.

Conclusions We found no association of maternal hCG concentrations on a fixed day in early pregnancy with development of hyperemesis gravidarum.