Preeclampsia can happen as early as 20 weeks into pregnancy, but that's rare. Symptoms often begin after 34 weeks. In a few cases, symptoms develop after birth, usually within 48 hours of delivery.

Can preeclampsia come on suddenly?

Preeclampsia can develop gradually, or come on quite suddenly, even flaring up in a matter of hours, though the signs and symptoms may have gone undetected for weeks or months.

What week does preeclampsia usually start?

Preeclampsia usually begins after 20 weeks of pregnancy in women whose blood pressure had been normal. Left untreated, preeclampsia can lead to serious — even fatal — complications for both you and your baby. If you have preeclampsia, the most effective treatment is delivery of your baby.