Reduced risk in Subsequent Pregnancies

For women who have a history of preeclampsia, what is the risk of recurrence in subsequent pregnancies?

A large prospective cohort study found the following:

In a first-time pregnancy, the risk of developing preeclampsia is 4.1%.
For women who do not have a history of preeclampsia, the risk of developing preeclampsia in subsequent pregnancies is 1.7% overall.
For women who developed preeclampsia in their first pregnancy, the risk of developing it in their second pregnancy is 14.7%.
For women who developed preeclampsia in their first and second pregnancies, the risk of developing it in their third pregnancy is 31.9%
For women who developed preeclampsia for the first time in their second pregnancy, the risk of developing it in their third pregnancy is 15.9% and the risk of developing it in their fourth pregnancy is 29% if they developed it in both their second and third pregnancy.
For women who developed preeclampsia for the first time in their third pregnancy, the risk of developing it in their fourth pregnancy is 14.7%.
For women who developed preeclampsia and delivered before 34 weeks in their first pregnancy, the risk of developing any preeclampsia in their second pregnancy is 29% and the risk of it being preeclampsia with delivery before 34 weeks is 6.8%.
For women who developed preeclampsia and delivered before 34 weeks in both their first and second pregnancies, the risk of developing preeclampsia and delivering before 34 weeks in their third pregnancy is 12.5%.

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Risk of pre-eclampsia in first and subsequent pregnancies: prospective cohort study

Objective To investigate whether pre-eclampsia is more common in first pregnancies solely because fewer affected women, who presumably have a higher risk of recurrence, go on to have subsequent pregnancies. Design Prospective cohort study. Setting Swedish Medical Birth Register. Participants 763 795 primiparous mothers who had their first births in Sweden, 1987-2004. Main outcome measures Pre-eclampsia. Results The risk of pre-eclampsia was 4.1% in the first pregnancy and 1.7% in later pregnancies overall. However, the risk was 14.7% in the second pregnancy for women who had had pre-eclampsia in their first pregnancy and 31.9% for women who had had pre-eclampsia in the previous two pregnancies. The risk for multiparous women without a history of pre-eclampsia was around 1%. The incidence of pre-eclampsia associated with delivery before 34 weeks’ gestation was 0.42% in primiparous women, 0.11% in multiparous women without a history of pre-eclampsia, and 6.8% and 12.5% in women who had had one or two previous pregnancies affected, respectively. The proportion of women who went on to have a further pregnancy was 4-5% lower after having a pregnancy with any pre-eclampsia but over 10% lower if pre-eclampsia was associated with very preterm delivery. The estimated risk of pre-eclampsia in parous women did not change with standardisation for pregnancy rates. Conclusions Having pre-eclampsia in one pregnancy is a poor predictor of subsequent pregnancy but a strong predictor for recurrence of pre-eclampsia in future gestations. The lower overall risk of pre-eclampsia among parous women was not explained by fewer conceptions among women who had had pre-eclampsia in a previous gestation. Early onset pre-eclampsia might be associated with a reduced likelihood of a future pregnancy and with more recurrences than late onset pre-eclampsia when there are further pregnancies. Findings are consistent with the existence of two distinct conditions: a severe recurrent early onset type affected by chronic factors, genetic or environmental, and a milder sporadic form affected by transient factors.