Elevated diastolic blood pressure until mid-gestation is associated with preeclampsia and small-for-gestational-age birth: a population-based register study

J Gunnarsdottir,U Högberg,T Akhter,A K Wikström,S Cnattingius

doi:10.1186/s12884-019-2319-2

J Gunnarsdottir, U Högberg + Show 3 more

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https://doi.org/10.1186/s12884-019-2319-2

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Abstract

BackgroundGestational hemodynamic adaptations, including lowered blood pressure (BP) until mid-gestation, might benefit placental function. We hypothesized that elevated BP from early to mid-gestation increases risks of preeclampsia and small-for-gestational-age birth (SGA), especially in women who also deliver preterm (< 37 weeks).MethodsIn 64,490 healthy primiparous women, the change in systolic and diastolic BP from early to mid-gestation was categorized into lowered (≥ 0 mmHg decreased), and elevated (≥ 1 mmHg increase). Women with chronic hypertension, chronic renal disease, pre-gestational diabetes and systemic lupus erythematosus were excluded. Risks of preeclampsia and SGA birth were estimated by logistic regression, presented with adjusted odds ratio (aOR) and 95% confidence intervals (CI). Further, the effect of BP change in combination with stage 1 hypertension (systolic BP 130–139 mmHg or diastolic BP 80–89 mmHg) in early gestation was estimated.ResultsCompared to women with lowered diastolic BP from early to mid-gestation, those with elevated diastolic BP had increased risks of preeclampsia (aOR: 1.8 [1.6–2.0]) and SGA birth (aOR: 1.3 [1.2–1.5]). The risk estimates were higher for preeclampsia and SGA when combined with preterm birth (aORs: 2.2 [1.8–2.8] and 2.3 [1.8–3.0], respectively). The highest rate of preeclampsia (9.9%) was seen in women with stage 1 hypertension in early gestation and a diastolic BP that was elevated until mid-gestation. This was three times the risk, compared to women with normal BP in early gestation and a diastolic BP that was decreased until mid-gestation. The association between elevated systolic BP from early to mid-gestation and preeclampsia was weak, and no significant association was found between changes in systolic BP and SGA births.ConclusionElevated diastolic BP from early to mid-gestation was associated with increased risks of preeclampsia and SGA, especially for women also delivering preterm. The results may imply that the diastolic BP starts to increase around mid-gestation in women later developing placental dysfunction disorders.

Highlights

Gestational hemodynamic adaptations, including lowered blood pressure (BP) until mid-gestation, might benefit placental function
An absence of mid-gestational BP drop is associated with preeclampsia, but it is less clear whether this absence may be relevant to small-for-gestational-age birth (SGA) births [4, 9,10,11]
Preeclampsia coincided with SGA in 290 of 1936 women who gave birth to SGA infants

Summary

Introduction

Gestational hemodynamic adaptations, including lowered blood pressure (BP) until mid-gestation, might benefit placental function. We hypothesized that elevated BP from early to mid-gestation increases risks of preeclampsia and small-for-gestational-age birth (SGA), especially in women who deliver preterm (< 37 weeks). In pregnancies complicated with placental dysfunction disorders (i.e., preeclampsia and birth of small-for-gestational-age (SGA) infants), the blood pressure (BP) is generally higher in early gestation than in uncomplicated pregnancies [1,2,3]. BP usually decreases from early to mid-gestation (“mid-gestational BP drop”), and this adaptation might benefit placental perfusion [8]. In women developing placental dysfunction disorders, systolic and diastolic BP increases faster than normal after mid-gestation [9,10,11]

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