Risk factors for recurrence of hypertensive disorders of pregnancy, a population-based cohort study.
INTRODUCTION
Hypertensive disorders of pregnancy (HDP) tend to recur from one pregnancy to the next. The aims of the study were to assess the recurrence risk according to type of HDP defined by gestational age at birth and to examine whether recurrence is associated with the following additional risk factors for HDP: maternal age, smoking, inter-delivery interval, diabetes, body mass index, and fetal growth restriction, and to assess temporal trends in these associations.


MATERIAL AND METHODS
All women with two singleton births in the Medical Birth Registry of Norway 1967-2012 (n = 742 980) were included in this population-based cohort study. Logistic regression was used to calculate odds ratios for the risk of recurrent HDP according to type of HDP.


RESULTS
The highest odds ratio of recurrence was observed for the same type of HDP based on gestational age at delivery. After gestational hypertension and term preeclampsia, the risk for the same type to recur increased 10-fold, whereas after late and early preterm preeclampsia, the risk increased 27- and 97-fold, respectively. The recurrence of early preterm preeclampsia was less influenced by additional risk factors compared with term HDP. Recurrence of early preterm HDP was significantly lower from 1993 onwards.


CONCLUSIONS
Recurrent HDP tended to be of the same type as the previous HDP. Risk of recurrence associated with additional risk factors was observed particularly after term. The odds ratio of recurrence of early preterm HDP was significantly lower from 1993 onwards.
['Ebbing|Cathrine|C|http://orcid.org/0000-0002-4331-1250', 'Rasmussen|Svein|S|http://orcid.org/0000-0002-5789-2922', 'Skjaerven|Rolv|R|http://orcid.org/0000-0002-6126-8655', 'Irgens|Lorentz M|LM|']
D000328:Adult D015331:Cohort Studies D005260:Female D006801:Humans D046110:Hypertension, Pregnancy-Induced D008423:Maternal Age D009664:Norway D010298:Parity D011247:Pregnancy D011254:Pregnancy in Diabetics D018566:Pregnancy, High-Risk D012008:Recurrence D012307:Risk Factors D055815:Young Adult
recurrence hypertensive disorders of pregnancy gestational hypertension preeclampsia High-risk pregnancy population study preterm birth