Risk of early or severe pre-eclampsia related to pre-existing conditions

Int J Epidemiol. 2007 Apr;36(2):412-9. doi: 10.1093/ije/dyl271. Epub 2007 Jan 25.


Background: Preeclampsia (PE), especially severe or early PE, is a leading cause of morbidity and mortality among mothers and infants. We estimated the population attributable fractions of severe or early PE associated with pre-existing conditions among nulliparous and multiparous women.

Methods: Among 70 924 women in the Danish National Birth Cohort, we used hospital discharge data to identify 2117 cases of PE, of which 449 were early (<37 weeks), 426 were severe (clinically diagnosed) and 228 were both early and severe. Prospective interview data were supplemented with hospital registry data to identify women with pre-existing conditions. Generalized estimating equations were utilized to estimate adjusted relative risks, and population attributable fractions were calculated with 95% CI.

Results: Pre-existing hypertension, diabetes, obesity or multiple gestation were associated with 22.3% (19.8-24.9) of all PE cases among nulliparous women. These conditions, or a prior preeclamptic pregnancy, were associated with 52.2% (46.4-57.9) of PE among multiparous women. Early PE was preceded by these pre-existing conditions among 34% (28.3-40.0) of affected nulliparous women and among 50% (37.5-63.4) of multiparous women. The fraction of severe PE associated with these conditions was 23% among nulliparas and 59% among multiparas. Being obese or overweight was associated with 15-17% of the population risk of early PE among nulliparous and multiparous women.

Conclusions: Pre-existing maternal and obstetric conditions are associated with a high proportion of severe or early cases of PE. Obesity and overweight contributed independently to the risk of pre-term PE, a finding with potentially profound public health implications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Cohort Studies
  • Female
  • Humans
  • Hypertension / complications
  • Infant, Newborn
  • Obesity / complications
  • Pre-Eclampsia / etiology*
  • Pregnancy
  • Pregnancy Outcome
  • Risk Assessment / methods
  • Risk Factors