Risk of pre-eclampsia according to gestational age across three decades: population-based study

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Epidemiology

Background:

• Pre-eclampsia is a serious pregnancy complication.
• Understanding gestational age-specific risks is crucial for management.
• Trends in pre-eclampsia incidence require ongoing investigation.

Purpose of the Study:

• To determine the risk of pre-eclampsia based on gestational age.
• To analyze changes in gestational-age-specific pre-eclampsia risks over decades.

Main Methods:

• Population-based study using Norwegian Medical Birth Registry data (1984-2019).
• Included over 1.9 million singleton pregnancies.
• Calculated pre-eclampsia risk per 1000 ongoing pregnancies at each gestational week, analyzing four time periods.

Main Results:

• Pre-eclampsia risk increased exponentially with gestational age (0.2/1000 at 28 weeks to 13.6/1000 at 42 weeks).
• Overall, 3.2% of pregnancies developed pre-eclampsia.
• The risk of pre-eclampsia was lower in 2010-2019 compared to 2000-2009, especially for term/post-term pregnancies.

Conclusions:

• Gestational age is a critical factor in pre-eclampsia risk.
• A recent decrease in pre-eclampsia risk, particularly in term pregnancies, was observed.
• This decline may be linked to increased obstetric interventions to manage high-risk pregnancies.