Pregnancy at Risk: Preexisting Conditions

Pregnancy at Risk

Preexisting Conditions

Kitty Cashion

Key Terms and Definitions

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F or most women, pregnancy represents a normal part of life. This chapter discusses the care of women for whom pregnancy represents a significant risk because it is superimposed on a preexisting condition. However, with the active participation of well-motivated women in the treatment plan and careful management from a multidisciplinary health care team, positive pregnancy outcomes are often possible.

Providing safe and effective care for women experiencing high risk pregnancy and their fetuses is a challenge. Although unique needs related to the preexisting conditions are present, these high risk women also experience the feelings, needs, and concerns associated with a normal pregnancy. The primary objective of nursing care is to achieve optimal outcomes for both the pregnant woman and the fetus.

This chapter focuses on diabetes mellitus and other metabolic disorders and cardiovascular disorders. Select disorders of the respiratory system, gastrointestinal system, integumentary system, and central nervous system (CNS), as well as substance abuse are also discussed.

Metabolic Disorders image

Diabetes Mellitus

Around the world the incidence of diabetes mellitus is increasing at a rapid rate. In 2005 an estimated 20.8 million people (7% of the population) in the United States had been diagnosed with some form of diabetes. In the United States, experts predict a marked future increase in the number of women with preexisting diabetes who will become pregnant (Moore & Catalano, 2009). Diabetes mellitus is currently the most common endocrine disorder associated with pregnancy, occurring in approximately 4% to 14% of pregnant women (Gilbert, 2007). The perinatal mortality rate for well-managed diabetic pregnancies, excluding major congenital malformations, is approximately the same as for any other pregnancy (Landon, Catalano, & Gabbe, 2007). The key to an optimal pregnancy outcome is strict maternal glucose control before conception, as well as throughout the gestational period. Consequently, for women with diabetes, much emphasis is placed on preconception counseling.

Pregnancy complicated by diabetes is still considered high risk. It is most successfully managed by a multidisciplinary approach involving the obstetrician, perinatologist, internist or endocrinologist, ophthalmologist, nephrologist, neonatologist, nurse, nutritionist or dietitian, and social worker, as needed. A favorable outcome requires commitment and active participation by the pregnant woman and her family. Planning the pregnancy is preferable, working before conception with the woman and her family (Landon et al., 2007).


Diabetes mellitus refers to a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both (American Diabetes Association [ADA], 2008). Insulin, produced by the beta cells in the islets of Langerhans in the pancreas, regulates blood glucose levels by enabling glucose to enter adipose and muscle cells, where it is used for energy. When insulin is insufficient or ineffective in promoting glucose uptake by the muscle and adipose cells, glucose accumulates in the bloodstream, and hyperglycemia results. Hyperglycemia causes hyperosmolarity of the blood, which attracts intracellular fluid into the vascular system, resulting in cellular dehydration and expanded blood volume. Consequently, the kidneys function to excrete large volumes of urine (polyuria) in an attempt to regulate excess vascular volume and to excrete the unusable glucose (glycosuria). Polyuria, along with cellular dehydration, causes excessive thirst (polydipsia).

The body compensates for its inability to convert carbohydrate (glucose) into energy by burning proteins (muscle) and fats. However, the end products of this metabolism are ketones and fatty acids, which, in excess quantities, produce ketoacidosis and acetonuria. Weight loss occurs as a result of the breakdown of fat and muscle tissue. This tissue breakdown causes a state of starvation that compels the individual to eat excessive amounts of food (polyphagia).

Over time, diabetes causes significant changes in both the microvascular and macrovascular circulations. These structural changes affect a variety of organ systems, particularly the heart, the eyes, the kidneys, and the nerves. Complications resulting from diabetes include premature atherosclerosis, retinopathy, nephropathy, and neuropathy.

Diabetes may be caused either by impaired insulin secretion, when the beta cells of the pancreas are destroyed by an autoimmune process, or by inadequate insulin action in target tissues at one or more points along the metabolic pathway. Both of these conditions are commonly present in the same person, and determining which, if either, abnormality is the primary cause of the disease is difficult (ADA, 2008). For additional information on diabetes, visit the American Diabetes Association’s website at


The current classification system includes four groups: type 1 diabetes, type 2 diabetes, other specific types (e.g., diabetes caused by genetic defects in B-cell function or insulin action, disease or injury of the pancreas, or drug-induced diabetes), and gestational diabetes mellitus (GDM) (ADA, 2008; Moore & Catalano, 2009). Approximately 90% of all pregnant women with diabetes have GDM (Gilbert, 2007). Of the women with pregestational diabetes, the majority (65%) of them have type 2 diabetes (Chan & Johnson, 2006).

Type 1 diabetes includes cases that are caused primarily by pancreatic islet beta cell destruction and that are prone to ketoacidosis. People with type 1 diabetes usually have an abrupt onset of illness at a young age and an absolute insulin deficiency. Type 1 diabetes includes cases currently thought to be caused by an autoimmune process, as well as those for which the cause is unknown (ADA, 2008; Landon et al., 2007).

Type 2 diabetes is the most prevalent form of the disease and includes individuals who have insulin resistance and usually relative (rather than absolute) insulin deficiency. Specific causes of type 2 diabetes are unknown at this time. Type 2 diabetes often goes undiagnosed for years because hyperglycemia develops gradually and is often not severe enough for the patient to recognize the classic signs of polyuria, polydipsia, and polyphagia. Most people who develop type 2 diabetes are obese or have an increased amount of body fat distributed primarily in the abdominal area. Other risk factors for the development of type 2 diabetes include aging, a sedentary lifestyle, family history and genetics, puberty, hypertension, and prior gestational diabetes. Type 2 diabetes often has a strong genetic predisposition (ADA, 2008; Moore & Catalano, 2009).

Pregestational diabetes mellitus is the label sometimes given to type 1 or type 2 diabetes that existed before pregnancy.

GDM is any degree of glucose intolerance with the onset or first recognition occurring during pregnancy. This definition is appropriate whether or not insulin is used for treatment or the diabetes persists after pregnancy. It does not exclude the possibility that the glucose intolerance preceded the pregnancy or that medication might be required for optimal glucose control. Women experiencing gestational diabetes should be reclassified 6 weeks or more after the pregnancy ends (ADA, 2008; Moore & Catalano, 2009).

White’s classification of diabetes in pregnancy.

Dr. Priscilla White, a physician who worked with pregnant women with diabetes during the 1940s, developed a classification system specifically for use with this group of women (Table 20-1). Dr. White’s system was based on age at diagnosis, duration of illness, and presence of vascular disease (Landon et al., 2007; Moore & Catalano, 2009). Her classification system has been modified through the years but is still frequently used today to assess both maternal and fetal risk. Women in classes A through C generally have good pregnancy outcomes as long as their blood glucose levels are well controlled. Women in classes D through T, however, usually have poorer pregnancy outcomes because they have already developed the vascular damage that often accompanies long-standing diabetes.

Metabolic changes associated with pregnancy

Normal pregnancy is characterized by complex alterations in maternal glucose metabolism, insulin production, and metabolic homeostasis. During normal pregnancy, adjustments in maternal metabolism allow for adequate nutrition for both the mother and the developing fetus. Glucose, the primary fuel used by the fetus, is transported across the placenta through the process of carrier-mediated facilitated diffusion, meaning that the glucose levels in the fetus are directly proportional to maternal levels. Although glucose crosses the placenta, insulin does not. Around the tenth week of gestation the fetus begins to secrete its own insulin at levels adequate to use the glucose obtained from the mother. Therefore, as maternal glucose levels rise, fetal glucose levels are increased, resulting in increased fetal insulin secretion.

During the first trimester of pregnancy the pregnant woman’s metabolic status is significantly influenced by the rising levels of estrogen and progesterone. These hormones stimulate the beta cells in the pancreas to increase insulin production, which promotes increased peripheral use of glucose and decreased blood glucose, with fasting levels being reduced by approximately 10% (Fig. 20-1, A). At the same time, an increase in tissue glycogen stores and a decrease in hepatic glucose production occur, which further encourage lower fasting glucose levels. As a result of these normal metabolic changes of pregnancy, women with insulin-dependent diabetes are prone to hypoglycemia during the first trimester.

During the second and third trimesters, pregnancy exerts a “diabetogenic” effect on the maternal metabolic status. Because of the major hormonal changes, decreased tolerance to glucose, increased insulin resistance, decreased hepatic glycogen stores, and increased hepatic production of glucose occur. Rising levels of human chorionic somatomammotropin, estrogen, progesterone, prolactin, cortisol, and insulinase increase insulin resistance through their actions as insulin antagonists. Insulin resistance is a glucose-sparing mechanism that ensures an abundant supply of glucose for the fetus. Maternal insulin requirements gradually increase from approximately 18 to 24 weeks of gestation to approximately 36 weeks of gestation. Maternal insulin requirements may double or quadruple by the end of the pregnancy (Fig. 20-1, B and C).

At birth, expulsion of the placenta prompts an abrupt drop in levels of circulating placental hormones, cortisol, and insulinase (Fig. 20-1, D). Maternal tissues quickly regain their prepregnancy sensitivity to insulin. For the nonbreastfeeding mother the prepregnancy insulin-carbohydrate balance usually returns in approximately 7 to 10 days (Fig. 20-1, E). Lactation uses maternal glucose; therefore the breastfeeding mother’s insulin requirements will remain low during lactation. On completion of weaning the mother’s prepregnancy insulin requirement is reestablished (Fig. 20-1, F).

Pregestational Diabetes Mellitus

Approximately 2 per 1000 pregnancies are complicated by preexisting diabetes. Women who have pregestational diabetes may have either type 1 or type 2 diabetes, which may or may not be complicated by vascular disease, retinopathy, nephropathy, or other diabetic sequelae. Type 2 is the more common diagnosis compared with type 1. Almost all women with pregestational diabetes are insulin dependent during pregnancy. According to White’s classification system, these women fall into classes B through T (see Table 20-1).

The diabetogenic state of pregnancy imposed on the compromised metabolic system of the woman with pregestational diabetes has significant implications. The normal hormonal adaptations of pregnancy affect glycemic control, and pregnancy may accelerate the progress of vascular complications.

During the first trimester, when maternal blood glucose levels are normally reduced and the insulin response to glucose is enhanced, glycemic control is improved. The insulin dose for the woman with well-controlled diabetes may have to be reduced to prevent hypoglycemia. Nausea, vomiting, and cravings typical of early pregnancy result in dietary fluctuations that influence maternal glucose levels and may also necessitate a reduction in the insulin dose.

Because insulin requirements steadily increase after the first trimester, the insulin dose must be adjusted accordingly to prevent hyperglycemia. Insulin resistance begins as early as 14 to 16 weeks of gestation and continues to rise until it stabilizes during the last few weeks of pregnancy.

Preconception counseling

Preconception counseling is recommended for all women of reproductive age who have diabetes because it is associated with less perinatal mortality and fewer congenital anomalies (Moore & Catalano, 2009). Under ideal circumstances, women with pregestational diabetes are counseled before the time of conception to plan the optimal time for pregnancy, establish glycemic control before conception, and diagnose any vascular complications of diabetes. However, estimates indicate that fewer than 20% of women with diabetes in the United States participate in preconception counseling (Landon et al., 2007).

Evidence-Based Practice

Preconception Counseling for Women with Diabetes

Critically Analyze the Data

The challenges of diabetes management become even greater during pregnancy, when hormonal changes, insulin resistance, and a growing fetus cause frequent shifts in glycemic control. Fetal risks associated with diabetes in pregnancy include anomalies, miscarriage, stillbirth, preterm birth, macrosomia leading to birth trauma or cesarean birth, and hypoglycemia. Maternal risks include increased retinopathy, nephropathy, preeclampsia, and injury from operative or cesarean birth.

The American Association of Clinical Endocrinologists (AACE, 2007) recommends that women be counseled before conception on the skills necessary to keep hemoglobin A1c (Hgb A1c) at less than 6%, blood glucose levels between 60 mg/dL fasting and 120 mg/dL at 1 hour after the first bite of a meal, and blood pressure under 130/80 mm Hg (AACE, 07). The guidelines further recommend evaluation of thyroid function, nephropathy, and retinopathy, as well as advice on healthy lifestyle and folic acid supplementation.

The professional guidelines on managing diabetes in pregnancy from the National Institute for Health and Clinical Excellence (Nice) (2008) recommend preconception counseling to optimize pregnancy outcomes. Good glycemic control should be established before conception and continue throughout pregnancy. The guidelines recommend counseling the diabetic woman seeking pregnancy about the role of diet, weight and exercise, the risks of hypoglycemia, the effects that nausea and vomiting can have on disease control, the risks of macrosomia, and assessment for retinopathy and nephropathy. Women should also know the risks to the neonate of hypoglycemia, as well as the possibility of obesity and diabetes later in life. They should understand the importance of glycemic control during labor and birth. The guidelines encourage women to attain a body mass index under 27 and a Hgb A1c below 6.1% before conception (NICE).

All persons with diabetes should be counseled about the benefits of a low-glycemic diet. Low-glycemic foods slow down the digestion of food and moderate the postprandial glucose spike. The prevention of glucose extremes is especially importance in pregnancy. A Cochrane meta-analysis found that diabetic women and their babies can benefit from eating low-glycemic foods such as fruits, vegetables, whole grains, and legumes (Tieu, Crowther, & Middleton, 2008).

Implications for Practice

Nurses are in an ideal position to counsel their patients with diabetes each year about the importance of glucose control and healthy habits before pregnancy. Women and their babies benefit from the skills that women learn about diet and exercise, as well as medical management of diabetes. Of particular benefit is the instruction in the low-glycemic diet. Women should be given the information they need to make informed decisions about their health and empowered by the knowledge to self-manage their care in partnership with the health team. Nurses should offer a positive message about their pregnancy and constant support, as well as frequent monitoring and follow-up. Women need emergency telephone numbers and other resources they can access anytime they have questions. Nurses can offer frequent encouragement and praise that pregnant women with diabetes are giving their babies the best possible start in life.

The woman’s partner should be included in the counseling to assess the couple’s level of understanding related to the effects of pregnancy on the diabetic condition and of the potential complications of pregnancy as a result of diabetes. The couple should also be informed of the anticipated alterations in management of diabetes during pregnancy and the need for a multidisciplinary team approach to health care. Financial implications of diabetic pregnancy and other demands related to frequent maternal and fetal surveillance should be discussed. Contraception is another important aspect of preconceptional counseling to assist the couple in planning effectively for pregnancy.

Maternal risks and complications

Although maternal morbidity and mortality rates have improved significantly, the pregnant woman with diabetes remains at risk for the development of complications during pregnancy. Poor glycemic control around the time of conception and in the early weeks of pregnancy is associated with an increased incidence of miscarriage. Women with good glycemic control before conception and in the first trimester are no more likely to miscarry than women who do not have diabetes (Moore & Catalano, 2009).

Poor glycemic control later in pregnancy, particularly in women without vascular disease, increases the rate of fetal macrosomia. Macrosomia has been defined in several different ways, including a birthweight more than 4000 to 4500 g, birthweight above the 90th percentile, and estimates of neonatal adipose tissue. Macrosomia occurs in approximately 40% of pregestational diabetic pregnancies and in up to 50% of pregnancies complicated by GDM (Landon et al., 2007; Moore & Catalano, 2009). Infants born to mothers with diabetes tend to have a disproportionate increase in shoulder, trunk, and chest size. Because of this tendency the risk of shoulder dystocia is greater in these babies than in other macrosomic infants. Women with diabetes therefore face an increased likelihood of cesarean birth because of failure of fetal descent or labor progress or of operative vaginal birth (birth involving the use of episiotomy, forceps, or vacuum extractor) (Landon et al.; Moore & Catalano).

Women with preexisting diabetes are at risk for several obstetric and medical complications. In general the risk of developing these complications increases with the duration and severity of the woman’s diabetes. In one study the rates of preeclampsia, preterm birth, cesarean birth, and maternal mortality were much higher in women with preexisting diabetes than in women who did not have this disease. Approximately a third of women who have had diabetes for more than 20 years, for example, develop preeclampsia. Women with nephropathy and hypertension in addition to diabetes are also increasingly likely to develop preeclampsia. The rate of hypertensive disorders in all types of pregnancies complicated by diabetes is 15% to 30%. Chronic hypertension occurs in 10% to 20% of all diabetic pregnancies, and in up to 40% of those in women who have preexisting renal or retinal vascular disease (Moore & Catalano, 2009).

Hydramnios (polyhydramnios) occurs approximately 10 times more often in diabetic than in nondiabetic pregnancies. Hydramnios (amniotic fluid in excess of 2000 ml) is associated with premature rupture of membranes, onset of preterm labor, and postpartum hemorrhage (Cunningham, Leveno, Bloom, Hauth, Gilstrap, & Wenstrom, 2005).

Infections are more common and more serious in pregnant women with diabetes than in pregnant women without the disease. Disorders of carbohydrate metabolism alter the body’s normal resistance to infection. The inflammatory response, leukocyte function, and vaginal pH are all affected. Vaginal infections, particularly monilial vaginitis, are more common. Urinary tract infections (UTIs) are also more prevalent. Infection is serious because it causes increased insulin resistance and may result in ketoacidosis. Postpartum infection is more common among women who are insulin dependent.

Ketoacidosis (accumulation of ketones in the blood resulting from hyperglycemia and leading to metabolic acidosis) occurs most often during the second and third trimesters, when the diabetogenic effect of pregnancy is the greatest. When the maternal metabolism is stressed by illness or infection, the woman is at increased risk for diabetic ketoacidosis (DKA) DKA can also be caused by poor patient compliance with treatment or the onset of previously undiagnosed diabetes (Moore & Catalano, 2009). The use of beta-mimetic drugs such as terbutaline for tocolysis to arrest preterm labor may also contribute to the risk for hyperglycemia and subsequent DKA (Cunningham et al., 2005; Iams, Romero, & Creasy, 2009).

DKA may occur with blood glucose levels barely exceeding 200 mg/dl, as compared with 300 to 350 mg/dl in the nonpregnant state. In response to stress factors such as infection or illness, hyperglycemia occurs as a result of increased hepatic glucose production and decreased peripheral glucose use. Stress hormones, which act to impair insulin action and further contribute to insulin deficiency, are released. Fatty acids are mobilized from fat stores to enter into the circulation. As they are oxidized, ketone bodies are released into the peripheral circulation. The woman’s buffering system is unable to compensate, and metabolic acidosis develops. The excessive blood glucose and ketone bodies result in osmotic diuresis with subsequent loss of fluid and electrolytes, volume depletion, and cellular dehydration. DKA is a medical emergency. Prompt treatment is necessary to prevent maternal coma or death. Ketoacidosis occurring at any time during pregnancy can lead to intrauterine fetal death. The incidence of DKA during pregnancy has decreased to approximately 2% from a rate of 20% or more in the past. The rate of intrauterine fetal demise (IUFD) with DKA, formerly approximately 35%, is currently 10% or less (Moore & Catalano, 2009) (Table 20-2).

TABLE 20-2

Differentiation of Hypoglycemia (Insulin Shock) and Hyperglycemia (Diabetic Ketoacidosis)



Slow (hours to days)


DKA, Diabetic ketoacidosis; IV, intravenous.

The risk of hypoglycemia (a less-than-normal amount of glucose in the blood) is also increased. Early in pregnancy, when hepatic production of glucose is diminished and peripheral use of glucose is enhanced, hypoglycemia occurs frequently, often during sleep. Later in pregnancy, hypoglycemia may also result as insulin doses are adjusted to maintain euglycemia (a normal blood glucose level). Women with a prepregnancy history of severe hypoglycemia are at increased risk for severe hypoglycemia during gestation. Mild to moderate hypoglycemic episodes do not appear to have significant deleterious effects on fetal well-being (see Table 20-2).

Fetal and neonatal risks and complications

From the moment of conception the infant of a woman with diabetes faces an increased risk of complications that may occur during the antepartum, intrapartum, or neonatal periods. Infant morbidity and mortality rates associated with diabetic pregnancy are significantly reduced with strict control of maternal glucose levels before and during pregnancy.

Despite the improvements in care of pregnant women with diabetes, intrauterine fetal demise (IUFD) (sometimes known as stillbirth) is still a major concern. Approximately 2% to 5% of all fetal deaths occur in women whose pregnancies are complicated by preexisting diabetes. Hyperglycemia, ketoacidosis, congenital anomalies, infections, and maternal obesity are thought to be reasons for fetal death. In the third trimester, fetal acidosis is the most likely cause of fetal death (Paidas & Hossain, 2009).

The most important cause of perinatal loss in diabetic pregnancy is congenital malformations, which account for 30% to 50% of all perinatal loss (Lindsay, 2006). The incidence of congenital malformations is related to the severity and duration of the diabetes. Hyperglycemia during the first trimester of pregnancy, when organs and organ systems are forming, is the main cause of diabetes-associated birth defects. Anomalies commonly seen in infants affect primarily the cardiovascular system, the CNS, and the skeletal system (Cunningham et al., 2005; Moore & Catalano, 2009) (see Chapter 24).

The fetal pancreas begins to secrete insulin at 10 to 14 weeks of gestation. The fetus responds to maternal hyperglycemia by secreting large amounts of insulin (hyperinsulinism). Insulin acts as a growth hormone, causing the fetus to produce excess stores of glycogen, protein, and adipose tissue and leading to increased fetal size, or macrosomia. Birth injuries are more common in infants born to mothers with diabetes compared with mothers who do not have diabetes and macrosomic fetuses have the highest risk for this complication. Common birth injuries associated with diabetic pregnancies include brachial plexus palsy, facial nerve injury, humerus or clavicle fracture, and cephalhematoma. Most of these injuries are associated with difficult vaginal birth and shoulder dystocia (Moore & Catalano, 2009). Hypoglycemia at birth is also a risk for infants born to mothers with diabetes (for further discussion of neonatal complications related to maternal diabetes, see Chapter 24).

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Oct 8, 2016 | Posted by in NURSING | Comments Off on Pregnancy at Risk: Preexisting Conditions

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