First of all I am not clear about how many children are already present. It is unwise to conceive till the blood pressure is controlled. If she has a caesarean section, and blood pressure recurs in the next pregnancy - the chance of complications of high blood pressure in mother and baby like brain haemorrhage, liver damage, eye changes, blindness, kidney failure are all there, and a small unhealthy baby as well, with a higher risk of fetal death.If on the other hand, blood pressure remains well controlled, pregnancy can go till term with healthy outcome for both. The chances of a caesarean section are increased by double, though. If there are already two or more children, she must consider to avoid pregnancy in order to reduce chances of blood pressure complications, which can increase with increasing age.