[Background] Hypertensive disease in pregnancy (HDP) is associated with a risk of subsequent hypertension. However the influence of normotensive blood pressure (BP) during pregnancy on future BP is not clear.
[Purpose] To investigate the association between BP measurements at their lowest levels in pregnancy, 20 weeks’ gestation (20 wks BP), and the risk of hypertension both ①during pregnancy and ②5 years after delivery.
[Methods] A total of 1542 women who delivered singletons at the National Center for Child Health and Development and Showa University Hospital were recruited between 2003 and 2007. They were invited to undergo a physical examination 5 years after delivery. Following exclusions (see below), 772 women completed the analysis. The influence of 20 wks BP on HDP and 5-year hypertension was assessed by multiple logistic regression analysis. The odds ratio for HDP was adjusted by age at delivery, pre-pregnancy BMI, familial history of hypertension (FH), previous history of HDP and parity (Model 1) and that for subsequent hypertension was adjusted by existence of HDP in index pregnancy, age, BMI, FH and renal disease (Model 2).
[Criteria] HDP was defined as sBP ≥ 140 mm Hg or dBP ≥ 90 mm Hg from 20 weeks’ gestation which remits by 12 weeks postpartum w/o proteinuria.
Hypertension at physical examination was defined as average sBP ≥ 140 mm Hg or average dBP ≥ 90 mm Hg or treatment with antihypertensive agents.
[Exclusion criteria] Chronic hypertension / Women who were pregnant and nursing when the physical examination was done
[Results] There were 26 HDP cases and 25 cases of 5-year hypertension (HDP: 6, normotensive control: 19).
① The odds ratio (95%CI) for HDP (adjusted by Model 1) is sBP:1.11 (for every 1 mmHg rise) (1.05~1.17), dBP:1.15(1.06~1.24) and BP category defined by the American Heart Association : 5.82 (for every 1 category increase)(2.15~15.76). A positive correlation between 20 wks BP and HDP risk was observed.
② The odds ratio for subsequent hypertension (adjusted by Model 2) is sBP: 1.06 (1.01-1.11), dBP:1.15(1.06-1.24) and BP category: 4.50(1.64-12.33).
20 wks BP is associated with subsequent hypertension, independent of HDP.
[Conclusions] 20 wks BP may predict both HDP and subsequent hypertension 5 years post delivery.