Women with hyperemesis gravidarum in their first pregnancy have a high risk of experiencing the same problem in a subsequent pregnancy, according to Norwegian researchers.

Unlike the “morning sickness” that many women experience during pregnancy, hyperemesis gravidum is a rare disorder that involves severe, persistent vomiting, which can lead to dehydration and serious metabolic disturbances.

Dr. Lill I. S. Trogstad, of Ulleval University Hospital, Oslo, and colleagues compared the risk of hyperemesis in second pregnancies in women who had and those who did not have hyperemesis in their first pregnancy. The investigators also examined whether the risk of hyperemesis changes if the next pregnancy is with a different father or if there is an interval between the deliveries.

The team used data from the Medical Birth Registry of Norway, 1967 through 1998. The study included 547,238 women with records of their first and second delivery. The results of the study are published in the British Journal of Obstetrics and Gynecology.

Overall, 0.9 percent of women had hyperemesis in their first pregnancy and 0.8 had hyperemesis in their second pregnancy. Among those with and without hyperemesis in their first pregnancy, 15.2 and 0.7 percent, respectively, experienced hyperemesis in the second pregnancy. Thus, the presence of hyperemesis in the first pregnancy raised the risk of developing the problem in the second pregnancy by 26-fold.

For women with hyperemesis in the first pregnancy, the risk of recurrent hyperemesis was 10.9 percent if there was a change in paternity, compared with 16.0 percent if there was no change in paternity.

Increasing time interval between deliveries increased the risk of hyperemesis in the second pregnancy, but only in women with no previous hyperemesis.

“The high risk of recurrence demonstrated in the present study is important in pre-pregnancy counseling,” Trogstad and colleagues explain. “Women with long intervals between pregnancies are at higher risk of hyperemesis as well as (high blood pressure during pregnancy) and other adverse pregnancy outcomes, and need more careful monitoring.”

SOURCE: British Journal of Obstetrics and Gynecology, December 2005.