Pregestational conditions: Nursing

Pregestational conditions are chronic medical problems that are present from before pregnancy and can pose a risk to the mother or the fetus during pregnancy. They include diabetes mellitus, thyroid problems, and certain cardiac conditions, as well as asthma.

Alright, now let’s quickly go over each of these conditions, starting with diabetes mellitus, which is when the body has trouble moving glucose from the blood into the cells, so blood glucose levels are constantly high. There are two main types of diabetes: type 1 diabetes, which is when the body doesn’t make enough insulin; and type 2 diabetes, which is when the body makes enough insulin, but the cells are insulin resistant, meaning they don’t respond to insulin by taking glucose in.

Next, there are thyroid problems, which can be split into hyper- and hypothyroidism. Hyperthyroidism occurs where there’s excess thyroid hormones, and this is generally caused by overproduction from the thyroid gland. Conversely, hypothyroidism is typically caused by an immune attack targeting the thyroid gland, causing destruction and inflammation, which results in low circulating thyroid hormones. Thyroid hormones are important because they increase the rate of metabolism in all cells, so they make us think, move, and talk faster, and they also increase heat generation. They also activate the sympathetic nervous system, the part of the nervous system responsible for the ‘fight-or-flight’ response, increasing cardiac output.

Third, there are cardiac conditions, which can be either congenital or acquired. Common congenital heart defects include atrial septal defect, or ASD; ventricular septal defect, or VSD; and patent ductus arteriosus, or PDA. On the other hand, acquired conditions that can complicate pregnancy include rheumatic heart disease; valvulopathies, which are caused by a defect in one or more of the four valves of the heart; and cardiomyopathies, which are disorders affecting the heart muscle, called the myocardium.

Finally, pregestational conditions also include asthma, which is a respiratory disorder characterized by a chronic inflammation of the airways, making them narrower and more difficult to breathe through.

Okay, now let’s see how each of these conditions affects pregnancy, starting with the pathology of diabetes mellitus. Early in pregnancy, diabetes can interfere with fetal organogenesis, resulting in major birth defects and spontaneous abortions. As pregnancy progresses, hormones released by the placenta increase the body’s resistance to insulin, resulting in higher levels of maternal blood glucose.

Fetal and neonatal effects include macrosomia, or a birth weight equal to or more than 4,000 grams; while diabetes-related renal impairment can cause uteroplacental insufficiency and intrauterine growth restriction, or IUGR. After delivery, infants of mothers with diabetes have a higher risk of neonatal complications, including hypoglycemia and respiratory distress syndrome. On the maternal end, diabetes during pregnancy can lead to an increased risk of obstetric complications, such as gestational hypertension, preeclampsia, preterm birth, and postpartum hemorrhage, as well as an increased risk of trauma during delivery and cesarean birth.

Next up, there’s hyperthyroidism, which is when excess thyroid hormones increase the basal metabolic rate, so it’s like the entire body is buzzing at twice the normal rate. Hyperthyroidism can cause spontaneous abortions, gestational hypertension, and placental abruption, as well as heart failure. In the fetus, it can lead to IUGR as well as fetal or neonatal thyrotoxicosis, and stillbirth.

Conversely, hypothyroidism causes an abnormal decrease in metabolic rate, telling the body to slow down more than usual. Hypothyroidism may interfere with becoming pregnant or it can be a cause of spontaneous abortion. Additionally, the fetus relies on maternal thyroid hormones until it is able to produce its own, which typically happens around 18 to 20 week’s gestation. So with maternal hypothyroidism, the development of the fetus is impaired, which can cause low birth weight and congenital hypothyroidism, as well as developmental delays.

Moving on, when it comes to cardiac conditions, pregnancy increases the workload of the heart due to an increase in blood volume, especially towards the third trimester. In the mother, this can worsen pre-existing cardiac pathology, and can even precipitate congestive heart failure. In addition, infants of mothers with cardiac conditions can have a higher risk of congenital cardiac defects, IUGR, and preterm birth.