Hypertensive disorders during pregnancy are associated with an
increased risk for subsequent chronic hypertension, thromboembolism,
and type 2 diabetes, according to the findings of a large cohort
study.

Gestational hypertension and pre-eclampsia have already been
associated with a high risk for maternal ischemic heart disease and
mortality, but little research has been done on their relation to
other types of cardiovascular outcomes and diabetes, Jacob Alexander
Lykke, MD, an obstetrician at the Rigshospitalet, in Copenhagen,
Denmark, explained in an oral presentation here at the annual meeting
of the Society for Maternal-Fetal Medicine 29th Annual Meeting.

"To our knowledge, this is the first study to describe the risk
gradient of subsequent thromboembolic events" in women who experience
hypertension during pregnancy, said Dr. Lykke.

He and his colleagues conducted a registry-based retrospective cohort
study of nearly 1.4 million women who had delivered 1 (n = 782,287)
or 2 (n = 536,419) singleton children in Denmark between 1978 and
2007. The women were followed for 13 to 15 years. Women with a
history of diabetes (type 1 or 2) were excluded from the analysis.

The presence of gestational hypertension did not significantly
increase the risk for subsequent thromboembolism. However, even mild
pre-eclampsia was associated with a hazard ratio for thromboembolism
of 5.1. With severe pre-eclampsia, the hazard ratio was 6.9 (P < .001
for both). When it came to type 2 diabetes, gestational hypertension
and mild and severe pre-eclampsia were all associated with a
significant increase in risk. The hazard ratio associated with each
condition was 3.32, 3.53, and 3.68, respectively, compared with women
who did not develop any hypertensive disorder (P < .001 for each).

When it came to chronic hypertension, pre-eclampsia alone was
associated with a hazard ratio of 4.07, which more than doubled to
8.72 when preterm delivery (PTD) was added to the mix. However, the
risk for hypertension associated with pre-eclampsia plus a small-for-
gestational-age (SGA) baby was no greater than that observed with pre-
eclampsia alone (4.17). The hazard ratio associated when all 3
conditions were calculated together was no larger than that observed
for pre-eclampsia plus preterm delivery (7.68). Pre-eclampsia raised
the risk for subsequent thromboembolism, with a hazard ratio of 1.61.
Adding preterm delivery to the calculation did not change that ratio,
but pre-eclampsia plus SGA was associated with a hazard ratio of
2.74. The risk was no higher when all 3 conditions were combined.

Among multiparous women, the number of pregnancies marked by pre-
eclampsia of any severity influenced the risk for subsequent chronic
hypertension. Pre-eclampsia during the first pregnancy was associated
with a hazard ratio for hypertension of 2.90. Women who experienced
pre-eclampsia during the second but not the first pregnancy had a
hazard ratio of 4.80, and if pre-eclampsia occurred during both
pregnancies, the hazard ratio was 7.31 (P < .001 for each group,
compared with women who did not develop pre-eclampsia).

Although he did not present the data, similar patterns occurred in
the risk for thromboembolism and type 2 diabetes, Dr. Lykke said.

"This was a beautiful study," said Marshall Lindheimer, MD, professor
emeritus of Obstetrics and Gynecology in Medicine at the University
of Chicago, in Illinois. Dr. Lindheimer, who was not involved in this
study, cited research conducted by Leon C. Chesley, PhD, in the
1970s, showing an association between pre-eclampsia and subsequent
cardiovascular events. However, among women who developed
hypertension only during their first pregnancy, the rate of
cardiovascular outcomes was no different than in the general
population.

Nevertheless, Dr. Lykke concluded that "hypertensive pregnancy
disorders are strongly associated with subsequent hypertension,
thromboembolism, and type 2 diabetes," with severity, parity, and
recurrence all affecting the degree of risk. He recommended
that "physicians and other healthcare professionals be encouraged to
include earlier pregnancy outcomes when calculating the risk of
cardiovascular events in their pregnant patients."

Society for Maternal-Fetal Medicine (SMFM) 29th Annual Meeting:
Abstract 10. Presented January 29, 2009.