sFlt1/PlGF and Selective Labor Induction to Prevent Preeclampsia at Term (PE37)

Description

Finding an effective prediction and prevention for term PE remains an unsolved challenge. From previous recent evidence it seems clear that prediction very close to term may achieve a high detection rate, but there is no evidence as to which strategy might be effective in preventing PE in high-risk women. The investigators postulate that a solution that would be applicable in most settings worldwide would require a simplified, pragmatic, approach. The rationale of this proposal is that PE could be reduced with a single-step lab test screening followed by induction of labor (IOL).

A single-step lab measure to detect PE. Combined algorithms using angiogenic factors with Doppler ultrasound and maternal features seem to achieve the highest performance in detecting pre-clinical PE. However, the need to train staff and change pregnancy care protocols renders difficult generalization in high-resource and even more low-resource settings. On the contrary, single lab tests can be more easily incorporated into the mainstream clinical practice and provide a widespread solution for high-resource settings and specially sub-optimal healthcare systems heavily affected by the consequences of term PE. Angiogenic factors are the obvious candidate for these purposes. The sFlt1/PlGF ratio at 35-36w predicts term PE with a DR of 82% and is a standardized lab test nowadays, realizable by ELISA with widely available automated lab platforms. Normal values in late pregnancy have been reported and are fairly similar among different populations. As preliminary research for this study, the investigators have confirmed that the gestational-age adjusted normal values of sFlt1/PlGF matched quite remarkably those previously published in different populations across Europe. A one-step screening with sFlt1/PlGF would select a 5-10% of the population with the highest risk for PE.

IOL at 37 weeks as an intervention in women at high-risk for PE. Previous trials based on statins have failed to show a reduction of PE in high-risk women. IOL at 37 weeks is an alternative to avoid PE in those high-risk women. IOL has consistently been demonstrated to be safe ( ) and does not affect long-term maternal quality of life ( ). Both the HYPITAT and the DIGITAT randomized trials showed that IOL did not increase caesarean rates or adverse neonatal outcomes ( ). A recent large randomized trial in the US has shown that even in low-risk women, universal IOL decreased cesarean section rates and was well accepted ( ). While in low-risk pregnancies labour induction has been found to be beneficial from 39 weeks (ARRIVE study), in women with placental-related conditions such as hypertension (HYPITAT) or small-for-gestational age (DIGITAT) it is 37+ weeks when the trade-off between neonatal and maternal benefits makes induction recommendable.

Therefore, the investigators hypothesize that a single-step universal screening for term PE based on sFlt1/PlGF ratio at 35-36.6 w followed by IOL at 37w in those women found to be at high risk might represent a feasible and reproducible strategy, applicable worldwide, to reduce the prevalence of term PE without increasing cesarean section rates or adverse neonatal outcomes.

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