Hypertension, also known as high blood pressure, in a mother-to-be can affect her unborn baby in many ways. A woman is considered to have hypertension if her blood pressure is 140/90 or higher; a reading of 180/110 or higher is considered severe. There are two distinct types of pregnancy hypertension: chronic and gestational. Each has a different cause and different effects on mother and baby. Severe gestational hypertension can lead to preeclampsia or eclampsia. The more severe the case of hypertension, the higher the risk for problems.
Chronic hypertension develops before the woman becomes pregnant. Sometimes the woman is aware that she has high blood pressure and may even be on medication for it. In other cases, the mom-to-be discovers she is hypertensive during a routine prenatal checkup in the first trimester. Chronic hypertension can lead to intrauterine growth restriction, or IUGR, a condition in which the unborn baby can't get enough nutrients and oxygen through the placenta and, therefore, the baby grows too slowly. Other possible problems stemming from chronic hypertension include preterm birth, stillbirth and placental abruption, a condition in which the placenta detaches from the uterus before the baby is born.
Gestational hypertension, also called pregnancy-induced hypertension, develops during pregnancy after the 20th week. Pregnancies with gestational hypertension also put the unborn baby at risk for IUGR, stillbirth, preterm birth and placental abruption. Gestational hypertension raises the likelihood of developing preeclampsia or eclampsia, conditions combining hypertension and protein in the urine.
Preeclampsia and Eclampsia
Preeclampsia is the less-severe form of the dangerous condition eclampsia. In both of these conditions, the pregnant woman not only has high blood pressure, but also has protein in her urine, which a urine test should detect during standard prenatal visits. These conditions can cause all of the same problems as other forms of high blood pressure and also a problem called acidosis, in which the baby's body builds up too much lactic acid and he falls unconscious in the womb. In the worst-case scenario, preeclampsia and eclampsia can lead to the death of both mother and baby if left untreated.
There is no known surefire prevention or treatment for either chronic or gestational hypertension during pregnancy. Limiting salt intake, using hypertension medications safe to use during pregnancy and bed rest may, however, help some pregnant women lower their blood pressure. The standard treatment for severe hypertension of either type or hypertension accompanied by protein in the urine is to deliver the baby as soon as possible. In some cases, this may involve delivery of a premature infant, which can affect the baby's health if it is not ready to thrive outside the womb.
Future problems for babies born to a hypertensive mother, especially babies who were born prematurely due to maternal hypertension, include learning disabilities, cerebral palsy, epilepsy, deafness and blindness. These babies may also be more prone to diabetes or hypertension of their own when they grow older.