Gestational hypertension

HELLP syndrome, a life-threatening complication of gestational hypertension, was first described by Weinstein in 1982 (Baltzer 2004).

Gestational hypertension (SIH) is the occurrence of de novo hypertension after the 20th week of gestation without further pathological findings (Herold 2022). In this case, the blood pressure values are ≥ 140 / 90 mmHg (Scharl 2019).

Hypertensive disorders of pregnancy (HES) include:

- Chronic hypertension.

In this case, hypertension already exists before conception or in the 1st trimester (Scharl 2019).

- Gestational hypertension (SIH).

This first occurs in pregnancy after 20 weeks gestation and does not last longer than 12 weeks post partum (Rath 2005).

- Preeclampsia

In this case, in addition to SIH, other new-onset abnormalities are found, such as proteinuria, renal insufficiency, liver involvement, uteroplacental dysfunction, and hematologic or neurologic complications (Herold 2022).

SIH is one of the pregnancy-induced hypertensions. They are divided into:

- 1. SIH without proteinuria

- 2. SIH with proteinuria and possibly also with edema. This form of the disease is also called pre-eclampsia (Herold 2022).

Hypertensive disorders of pregnancy are a leading cause of both maternal and perinatal mortality worldwide (Gestational Hypertension and Preeclampsia 2020).

SIH without proteinuria develops in approximately 10% of all pregnant women (Herold 2022).

SIH is caused by the pregnancy itself (Schwenger 2021).

Risk factors of SIH are:

- nulliparity

- anamnestically known:

- renal disease

- diabetes mellitus

- preeclampsia in previous pregnancy

- chronic hypertension

- antiphospholipid antibody syndrome (Kasper 2015)

- obesity

- maternal age < 15 years or > 35 years

- multiple pregnancy

- Hydrops fetalis

- trisomy

- In vitro fertilization (IVF)

- Bladder mole (Scharl 2019)

During pregnancy, cardiac output increases by up to 40%. Most of this is due to the increase in stroke volume.

In the 2nd trimester, systemic vascular resistance decreases. This is accompanied by a drop in blood pressure. There is already an increase in perinatal morbidity and mortality from a blood pressure of 140 / 90 mmHg (Kasper 2015).

The exact pathophysiology of SIH with proteinuria remains unknown. Studies show excessive placental production of antagonists of vascular epithelial growth factor VEGF and transforming growth factor beta (TGF- beta). This disrupts endothelial and glomerular renal function (Kasper 2015).

In SIH, there is a blood pressure elevation of > 135 / 85 mmHg (Dudenhausen 2011).

In the 1st trimester, the mother should first be assessed for risk.

In the 2nd and 3rd trimesters, blood pressure measurement and any existing proteinuria are particularly important in screening for SIH during regular examinations according to the maternity guidelines (Scharl 2019).

Estimation of the risk of preeclampsia can be performed by Doppler sonography of the uterine artery and determination of angiogenic factors (Scharl 2019).

Blood pressure measurements

These should always be performed with cuffs adapted to the circumference of the upper arm, the primary measurement always on both sides and always after an appropriate resting phase in the sitting pregnant woman (Scharl 2019).

24 h blood pressure measurement

This examination is used for differential diagnostic clarification of hypertension, in particular to exclude "white coat hypertension". Furthermore, conclusions can be drawn about a possible loss of the circadian rhythm, which is a prognostically unfavorable sign. In addition, the success of any antihypertensive therapy can be assessed (Scharl 2019).

Doppler sonography

The examination should be performed in the 2nd trimester. Here, the mean pulsatility index (PI) is determined as the best marker for the prediction of preeclampsia. The sensitivity is up to 93% (Scharl 2019).

- White coat hypertension

In this case, SIH can occur in up to 40% of cases and preeclampsia in approximately 8% as the pregnancy progresses (Scharl 2019).

- Preeclampsia

In this case, in addition to hypertension, there is another organ manifestation (Scharl 2019), such as proteinuria. Pre-eclampsia occurs in approximately 25% of SIH sufferers (Herold 2022).

- HELLP- syndrome (haemolysis, elevated liver enzymes, low platelet count).

This is found in approximately 0.5% of SIH patients (Herold 2022). The main symptoms are pain in the right upper abdomen due to capsular tension in the liver, nausea and vomiting (Baltzer 2004). This is a life-threatening complication (Baltzer 2004 / Schölmerich 2005).

- Eclampsia

Eclampsia is found in approximately 0.1% of those affected by SIH (Herold 2022). Generalized tonic-clonic convulsions occur (Schölmerich 2005).

Eclampsia is also a life-threatening complication (Baltzer 2004 / Schölmerich 2005).

- Apoplexy

When coagulation disorders or platelet dysfunction occur, the risk of apoplexy increases (Kasper 2015).

- Developmental disorders in children

These occur in the context of SIH due to degenerative processes in the placenta (Dellas 2022).

Although SIH is self-limited and resolves without therapy within a few weeks post partum, early therapy is essential because of the morbidity and mortality to both mother and child (Kasper 2015).

Mild SIH:

Here, conservative treatment with limitation of physical activity, close monitoring of blood pressure, renal function and the fetus is recommended (Kasper 2015).

Severe SIH:

Blood pressure levels ≥ 160 / 110 mm Hg are at significantly increased risk for preeclampsia, preterm delivery, or apoplexy (Scharl 2019).

In this case, pregnant women are often recommended to have an immediate (premature) delivery (Kasper 2015).

Drug therapy should be given starting at blood pressure values of 150 - 160 / 100 - 110 mmHg. For blood pressure values ≥ 160 / 110 mm Hg, blood pressure adjustment under stationary conditions is recommended (Scharl 2019).

However, elevated arterial blood pressure should be lowered slowly, otherwise cerebrovascular adverse events may occur (Kasper 2015). Lowering it too drastically also decreases placental perfusion and thus poses an acute fetal impairment (Scharl 2019).

Oral medications available include:

- Alpha- methyldopa

This represents the drug of 1st choice. Dosage recommendation: 250 - 500 mg 2 - 4 x / d p. o., maximum dose 2 g / d (Scharl 2019).

- Nifedipine ret.

Dosage recommendation: 20 - 60 mg orally, maximum dose 120 mg / d (Scharl 2019).

- Labetalol (Kasper 2015).

Dosage recommendation: Initial 3 x 200 mg / d, maximum dose is 4 x 300 mg / d (Scharl 2019).

Target blood pressure values are between 130 - 150 mmHg systolic and between 80 - 100 mmHg diastolic (Scharl 2019).

Because of the negative effects on fetal development in the 2nd and 3rd trimesters, should be avoided:

- Angiotensin- receptor blockers

- ACE- inhibitors (Kasper 2015).

According to the guideline, although no teratogenic effects have been proven, they are nevertheless contraindicated in the 2nd and 3rd trimesters because they lead to acute renal failure in the newborn (Scharl 2019).

For rapid acute blood pressure lowering, they can be used:

- Urapidil

Dosage recommendation: Initial 6.25 mg slowly i. v. (over 2 min), then via perfusor 3 - 24 mg / h (Scharl 2019).

- Dihydralazine

Dosage recommendation: Initial 5 mg i. v., followed by 2 - 20 mg / h via perfusor (Scharl 2019)

- Magnesium sulfate

Since magnesium interacts with N- methyl- D- aspartate receptors in the CNS, they may reduce the risk of seizures in mothers with SIH (Kasper 2015).

The prognosis depends on the extent of hypertension, as this determines the perinatal mortality of both mother and child (Herold 2022). In SIH without proteinuria, the prognosis is good (Herold 2022).

The risk of developing gestational hypertension without proteinuria in a new pregnancy ranges from 16-47% (Scharl 2019).

Prophylaxis

The risk of developing preeclampsia can be reduced by low-dose aspirin from the end of the 1st trimester (Kasper 2015). According to the guideline, the dosage recommendation is 150 mg / d ASA from the 16th SSW. This can significantly reduce the risk of developing preeclampsia or SIH before the 37th week of gestation by up to 63% (Scharl 2019).

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