Raised blood pressure
We take two measurements when taking blood pressure, the systolic pressure is written on top and is when the pulse is first heard as the pressure in the cuff is reduced. The diastolic pressure is recorded as the pulse disappears again as the pressure in the cuff drops even further. Blood pressure greater than 140/90 mmHg is called hypertension or raised blood pressure. Hypertension in pregnancy accounts for about a third of all maternal deaths in pregnancy, so it is manged with great care. There are many reasons for a raised blood pressure, each with its own risks and problems. We generally classify hypertension in pregnancy into four groups:
- Preexisting hypertension: This is where the women already has blood pressure (BP) problems before getting pregnant (she may not be aware of this). If it is possible to control the BP during pregnancy, the outcome is usually very good, but there are more small babies born ro mothers with hypertension.
- Pregnancy induced hypertension: This is where the BP only rises in the later stages of pregnancy. If the baby is growing well, the outcome is usually excellent, so long as the BP is controlled.
- Pre-eclampsia: This is a condition where the placenta has problems establishing in the womb. As a result. Later in the pregnancy, the placenta starts to produce toxins, which can affect every organ in the body. It can affect the vessels, leading to high blood pressure and fluid (oedema) leaking from vessels all over the body (not just the ankles). The kidneys are affected and leak valuable protein into the urine. The liver and platelets in the blood can be affected (HELLP syndrome), and the brain can be affected, leading the patient to feel unwell, often with headaches and flashing lights. If not controlled, the woman may develop eclampsia, where they become unconscious and start to have seizures or fits. Often the only way to help the woman is to end the pregnancy, deliver the baby and most importantly, the placenta, which is the source of the toxins.
Blood tests including a full blood and platelet count, urea and electrolytes, liver function tests, uric acid, liver function tests and a blood clotting screen are undertaken to assess the impact of the blood pressure on the mother as well as elucidating the likely type of hypertension she is suffering from.
If a pregnancy has reached maturity or term, delivery can be considered as a solution to hypertension, in addition to drug therapy to ensure the level of raised blood pressure does not put the mother or baby at risk. Because hypertension is only one aspect of pre-eclampsia, and this disease carries such great risk and deliver at term is expedited while a multidisciplinary team helps manage the disease.
Pre term hypertension involves walking a tightrope between risking the mother with high blood pressure, while trying to achieve greater maturity for the fetus, who is often small for gestational age. The final decision is usually taken by the multidisciplinary team looking after the patient.