Hypertension or high blood pressure is one of the more serious complications that can affect a pregnancy.
A small percentage of pregnant women who have raised blood pressure will have it as a pre-existing condition and may be on medication even before conception. This is chronic hypertension, also known as "essential hypertension".
There is a small group of women who may have pre-existing hypertension because of a known underlying disease, usually of the kidneys. In such women, the hypertension is, strictly speaking, not a pregnancy complication. Rather, it is a concomitant condition that will need to be monitored and controlled during the course of the pregnancy. This is because pre-existing hypertension has a potential for worsening or being complicated by turning into pre-eclampsia.
This brings us to the main hypertensive condition to affect pregnancy: pre-eclampsia. The majority of women who develop pre-eclampsia have no identifiable underlying cause.Pre-eclampsia is also by the older term "pre-eclamptic toxaemia" (PET).
There is a variant of this condition where raised blood pressure occurs for the first time during pregnancy but it is not accompanied by loss of protein in urine. The correct term for this variant is ‘Pregnancy Induced Hypertension or ‘PIH’.
In North America, pre-eclampsia was also known as "EPH gestosis" in the past. All these terms mean exactly the same thing.
This condition is significant because, if poorly managed, it may lead to loss of the baby. More serious still, both the mother's and the baby's lives could be in danger. Pre-eclampsia cannot be cured while the woman is still pregnant. All the measures that are taken are meant to control the condition, to allow the fetus to grow to a viable stage. This is why preterm delivery and caesarean section are common and predictable consequences of this condition. On the other hand, if the condition is well controlled, as is sometimes the case, the pregnancy will be allowed to go to term and, with a bit of luck, there will be a spontaneous labour and normal delivery. However, no woman with this condition should convince herself that this is what is aimed for. It should be seen as a bonus if it is achieved.
In this chapter, we set out to answer specific questions about pre-eclampsia and other hypertensive conditions in pregnancy.
Blood pressure in pregnancy
What happens to blood pressure in pregnancy?
The normal tendency is for the blood pressure to fall slightly during pregnancy. It may reach a nadir about halfway through, at around eighteen to twenty weeks of gestation. It tends to stay there and then may rise back towards the pre-pregnancy levels towards the end of the pregnancy. This is the experience of the majority of pregnant women.
Can the blood pressure fall to a dangerous level?
This is extremely unusual and this possibility can safely be ignored.
Occasionally, women may experience light-headedness and feeling faint during pregnancy. This tends to occur on prolonged standing, walking in the sun or rising rapidly from a sitting position.
Rarely, actual blackouts have been reported.
What should a woman do if she experiences any of the above?
The sensible thing is to avoid the precipitating factors. However, it is usually an unnecessary overkill for the mother to put restrictive limits to her activities, just because she has had the odd feeling of faintness in pregnancy.
As a rule, the fall in blood pressure is temporary and lasts a few seconds before the self-regulatory mechanisms kick in to correct it. Feeling light-headed should never be an overriding worry.
What about raised blood pressure (hypertension)?
This is a problem.
There is no point in any doctor or midwife trying to say "not to worry" when a mother is noted to have raised blood pressure in pregnancy. The action that is taken is the important issue for the expectant mother to concentrate upon.