Nurmi M, et al. - In this study, the recurrence rate of hyperemesis gravidarum in subsequent pregnancies was determined, chronological patterns of recurrence of the condition were elucidated, and maternal, environmental and pregnancy-related factors associated with recurring hyperemesis gravidarum were analyzed. The majority of pregnancies following an earlier hyperemetic pregnancy did not display recurrence of hyperemesis gravidarum, but these slightly predict hyperemetic pregnancies occurrence in the next pregnancies. Researchers identified only a few factors associated with recurring hyperemesis. Although woman’s first hyperemetic pregnancy could not determine the probability of recurrence of hyperemesis gravidarum in a subsequent pregnancy, it is reassuring to know that there appeared no increased likelihood of hyperemesis with each pregnancy and that after one pregnancy with hyperemesis, the following pregnancy may be different.

Methods

• From Hospital Discharge Register and Medical Birth Register, researchers retrieved data of women who had at least one pregnancy ending in delivery following a pregnancy diagnosed with hyperemesis gravidarum out of all pregnancies ending in delivery in Finland between 2004 and 2011 (1836 women, 4103 pregnancies; 1836 index pregnancies and 2267 subsequent pregnancies).
• They chose the first pregnancy with hyperemesis gravidarum diagnosis as the index pregnancy; by comparing the number of hyperemetic pregnancies which followed the index pregnancy to the total number of pregnancies which followed the index pregnancy, they calculated the recurrence rate.
• They presented the recurrence patterns of hyperemesis gravidarum by presenting the chronological order of the women’s pregnancies beginning from the index pregnancy to the end of the follow-up period.
• In both the index pregnancies and in pregnancies following the index pregnancy, they analyzed the associations between recurring hyperemesis and age, parity, pre-pregnancy body mass index, smoking, marital and socioeconomic status, domicile, month of delivery, assisted reproductive technology (ART), sex and number of fetuses.

Results

• Researchers identified 544 pregnancies with a hyperemesis diagnosis and 1723 pregnancies without a hyperemesis diagnosis following the index pregnancies.
• The overall hyperemesis gravidarum recurrence rate of 24% was evident in pregnancies following the index pregnancy.
• In case of more than one subsequent pregnancy, hyperemesis was diagnosed in 11% of women in all of their pregnancies.
• In the index pregnancies, women with parity of two vs those with parity of one showed common recurrence of hyperemesis gravidarum (adjusted OR=1.33, p=0.046).
• Lower recurrence of hyperemesis was noted among overweight women (adjusted OR=0.58, p=0.036) or women who smoked after the first trimester (adjusted OR=0.27, p < 0.001).
• In the comparison of the subsequent pregnancies, lower odds of recurring hyperemesis were evident with quitting smoking in the first trimester (adjusted OR=0.32, p=0.010) and smoking continued after the first trimester (adjusted OR=0.38, p=0.002).
• Higher odds of recurring hyperemesis were noted in association with female sex of the fetus (adjusted OR=1.29, p=0.012).