title: First trimester markers of preeclampsia in twins: maternal mean arterial pressure and uterine artery Doppler pulsatility index.
abstract: OBJECTIVE
  This study aims to evaluate the distribution of mean arterial pressure (MAP) and uterine artery Doppler pulsatility index (PI) in first trimester twins with and without preeclampsia.
  
  
  METHODS
  A total of 147 twins were recruited from a specialist clinic and 110 unaffected singleton pregnancies attending the same institution served as controls. MAP and Doppler PI values were expressed in multiples of the gestation-specific median using published equations.
  
  
  RESULTS
  Among the twins, 12 had preeclampsia and two had pregnancy-induced hypertension. Among unaffected pregnancies, there was no significant difference in MAP levels between twins and singletons (P = 0.17, Wilcoxon rank sum test, two-tail). However, the Doppler PI levels were highly statistically significantly lower than in singletons (P < 0.0005). MAP was unrelated to chorionicity (P = 0.46), but there was a statistically significant increase in Doppler PI among monochorionic compared with dichorionic twins (P < 0.01). In twins with preeclampsia, MAP was significantly higher than in unaffected twins (P < 0.02, one-tail), whereas Doppler PI levels were significantly reduced (P < 0.01, two-tail).
  
  
  CONCLUSIONS
  If first trimester screening for preeclampsia is extended to twins, a different normal median Doppler PI equation will be needed. Contrary to expectations, Doppler PI levels may not be raised in affected twins, although this needs confirmation in a larger study.
authors.affiliation: Department of Obstetrics and Gynecology, Assaf Harofeh Medical Center, Zerifin, Israel, affiliated with the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Svirsky
authors.forename: S
authors.initials: S
authors.lastname: Yagel
authors.forename: I
authors.initials: I
authors.lastname: Ben-Ami
authors.forename: H
authors.initials: H
authors.lastname: Cuckle
authors.forename: E
authors.initials: E
authors.lastname: Klug
authors.forename: R
authors.initials: R
authors.lastname: Maymon
mesh_terms: D015415:Biomarkers; D001794:Blood Pressure; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D011225:Pre-Eclampsia / Q000503:physiopathology*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D059285:Pregnancy, Twin / Q000502:physiology*; D011446:Prospective Studies; D018608:Ultrasonography, Doppler; D055988:Uterine Artery / Q000503:physiopathology*
chemical_list: D015415:Biomarkers