Routine first-trimester pre-eclampsia screening and risk of preterm birth

Routine first-trimester pre-eclampsia screening and risk of preterm birth

REVIEWED BY Gina Humphries | ASA SIG: Women’s Health

REFERENCE | Authors: V Giorgione, O Quintero Mendez, A Pinas, W Ansley, B Thilaganathan

WHY THE STUDY WAS PERFORMED

Preterm birth is a major public health problem affecting between 5–18% of all pregnancies. Complications associated with preterm birth are the primary cause of death in children under 5 years of age. Preterm births may be iatrogenic or spontaneous. Latrogenic preterm birth accounts for 20–30% of all preterm births. Latrogenic preterm birth may be related to pre-eclampsia, fetal growth restriction, placenta previa or placental abruption. However, most preterm births occur spontaneously. Uteroplacental malperfusion associated with preeclampsia and fetal growth restriction has been proposed as a causative factor for spontaneous preterm birth. The primary objective of this study was to establish whether there is a common uteroplacental etiology in the first trimester between spontaneous and iatrogenic preterm birth.

HOW THE STUDY WAS PERFORMED

The study by Giorgione et al. retrospectively examined the risk factors for preterm birth in 11,437 women who had undergone first trimester screening examinations for preterm pre-eclampsia, and the risk of spontaneous preterm birth in those women at high risk for preterm pre-eclampsia. First trimester screening examinations were undertaken at 11 to 13 weeks’ gestation as confirmed via crown-rump length measurement. Screening for preterm pre-eclampsia was performed as per the Fetal Medicine Foundation (FMF) algorithm, which includes maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index and pregnancy-associated plasma protein-A (PAPP-A). Those patients determined to be at risk of ≥1 in 50 for preterm preeclampsia were classified as high risk for preterm birth. These patients were offered prophylactic aspirin, growth scans at 28 and 36-week gestation and labour induction from 40 weeks’ gestation.

“Women who are classified in the first trimester as being at high risk of developing preterm pre-eclampsia are also at increased risk of both iatrogenic and spontaneous preterm birth.”

WHAT THE STUDY FOUND

The study found that women assessed as a high risk for placental dysfunction in the first trimester were at an increased risk of preterm birth. Of the 11,437 women screened for preterm birth using the FMF algorithm, 4.2% had a preterm birth of which 64.8% were spontaneous and 35.2% were iatrogenic. Compared to women delivering at term, those who delivered preterm were more likely to be assessed as high risk for preterm pre-eclampsia (19.4% vs 6.6%, P < 0.0001). In particular, the data demonstrated that a high risk of preterm pre-eclampsia had a 6-fold higher risk of iatrogenic preterm birth and a 2-fold higher risk of spontaneous preterm birth. Women who had a higher MAP, a higher uterine artery pulsatility index and lower PAPP-A were also significantly more likely to deliver preterm than those women who did not.

RELEVANCE TO CLINICAL PRACTICE

Women identified in first trimester screening as at risk for preterm pre-eclampsia should be considered at risk of preterm birth. Maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index and pregnancy-associated plasma protein-A (PAPP-A) should be considered when assessing a patient’s risk. Sonographers play an important role in accurately assessing the mean uterine artery pulsatility index in the first trimester and so play an important role in minimising a patient’s risk of preterm birth.