19.2 High-Risk Pregnancy

Health care providers use the term high-risk pregnancy to describe a situation in which a mother, her fetus, or both are at higher risk for problems during pregnancy or delivery compared to a typical pregnancy. For example, pregnant women who have chronic health problems, such as hypertension or diabetes, may be classified as having a high-risk pregnancy, even if the condition is well-controlled, because these conditions put the mother and/or fetus at risk for complications. Women with high-risk pregnancies may require specialized care from maternal-fetal specialists or in perinatal health care centers, depending on their risk factors.^[1]

When discussing high-risk pregnancies, it is important to consider common causes of maternal and fetal morbidity and mortality. Morbidity refers to poor outcomes caused by illness or disease. Mortality refers to the number of deaths caused by a specific illness or disease. Maternal morbidity and mortality are health concerns that relate to pregnancy and childbirth.

Maternal mortality is unacceptably high around the world and in the United States. About 287,000 women died around the world  in 2020 related to pregnancy and childbirth, and most cases could have been prevented. According to the World Health Organization (WHO), the majority of maternal deaths around the world are caused by the following conditions^[2]:

• Hemorrhage
• Infection
• High blood pressure disorders of pregnancy, including preeclampsia and eclampsia
• Complications related to labor and delivery
• Unsafe abortion

In the United States, the Centers for Disease Control and Prevention (CDC) tracks pregnancy-related deaths, which are slightly different from maternal deaths around the world. In the U.S., the main causes of pregnancy-related deaths include the following^[3]:

• Hemorrhage
• Infection and sepsis
• Cardiovascular conditions, such as:
  • Pulmonary emboli
  • Cerebrovascular accidents
  • Blood pressure disorders of pregnancy, including preeclampsia and eclampsia
  • Cardiomyopathy
  • Heart disease
• Anesthesia complications
• Amniotic fluid embolism
• Chronic noncardiovascular conditions, such as diabetes

In addition to common causes of pregnancy-related deaths, many other factors can cause a pregnancy to be classified as high risk, including existing health conditions, the mother’s age, lifestyle choices, and other conditions that occur during pregnancy or labor and delivery.^[4]

Preexisting Health Conditions

Existing health conditions that can cause a pregnancy to be classified as high risk include the following^[5]:

• High blood pressure: Uncontrolled high blood pressure can damage the mother’s kidneys and increase the risk for low birth weight or preeclampsia. Pregnant women have their blood pressure checked at every prenatal visit so that elevated blood pressure is diagnosed and treated.
• Polycystic ovary syndrome (PCOS): Women with PCOS have higher rates of complications such as pregnancy loss before 20 weeks of pregnancy, gestational diabetes, preeclampsia, and cesarean delivery.
• Diabetes: Women diagnosed with diabetes type 1 or 2 before pregnancy must manage their blood sugar levels with tight control throughout pregnancy. During the first few weeks of pregnancy, often before a woman even knows she is pregnant, high blood sugar levels can cause congenital anomalies. Infants of mothers with diabetes tend to be large and are likely to have hypoglycemia soon after birth.
• Kidney disease: Women with kidney disease can have difficulties conceiving and staying pregnant and may also experience problems during pregnancy, including preterm delivery, low birth weight, and preeclampsia. Nearly one fifth of women who develop preeclampsia early in pregnancy have undiagnosed kidney disease. Pregnant women with kidney disease require additional treatments, changes in diet and medication, and frequent visits to their health care provider.
• Autoimmune disease: Autoimmune disease such as lupus and multiple sclerosis can increase a woman’s risk for problems during pregnancy and delivery. For example, women with lupus are at increased risk for preterm birth and stillbirth. Furthermore, certain medicines prescribed to treat autoimmune diseases may be harmful to the fetus, meaning a woman with an autoimmune disease will need to work closely with a health care provider throughout pregnancy.
• Thyroid disease: Uncontrolled thyroid disease, such as an overactive or underactive thyroid, can cause fetal problems, such as heart failure, poor weight gain, and brain development problems.
• Obesity: Being obese before pregnancy or excessive weight gain during pregnancy is associated with poor pregnancy outcomes. For example, obesity increases a woman’s chance of developing gestational diabetes, which can cause a fetus to be larger than normal, making the birth process more difficult. Obesity before pregnancy is associated with an increased risk of structural problems with the baby’s heart. Complications can also develop from excessive weight gain during pregnancy. The Institute of Medicine recommends that overweight women gain no more than 15–25 pounds during pregnancy and that women with obesity gain no more than 11–20 pounds.
• HIV/AIDS: HIV can be transmitted to a fetus during pregnancy, labor and delivery, and breastfeeding. Fortunately, there are many effective medications that can reduce and prevent the spread of HIV from mother to fetus or child. Cesarean delivery before the amniotic fluid ruptures can also prevent mother-to-child transmission of HIV, as well as bottle feeding instead of breastfeeding. These treatments have led to a dramatic decrease in the mother-to-infant transmission rate of HIV to less than 1%.

Age

Age can be a factor in high-risk pregnancies^[6]:

• Teenagers: Pregnant teenagers are more likely to develop pregnancy-related high blood pressure and anemia, as well as preterm labor. Also, teens may not realize they have a sexually transmitted infection (STI), which can cause complications with the pregnancy or the fetus. In addition, teens are less likely to get prenatal care or to keep prenatal appointments, which reduces the health care provider’s ability to evaluate, identify, and treat risks before these risks become problems.
• First-time pregnancy after age 35: Research shows that older women are at a higher risk for certain problems than younger women, including the following:
  • Ectopic pregnancy
  • Pregnancy-related high blood pressure
  • Gestational diabetes
  • Pregnancy loss
  • Delivery complications, such as excessive bleeding or prolonged labor (lasting more than 20 hours)
  • Cesarean delivery
  • Fetal genetic disorders, such as Down syndrome

Lifestyle Factors

Several lifestyle factors can contribute to high-risk pregnancies^[7]:

• Alcohol use: Drinking alcohol during pregnancy can increase the baby’s risk for fetal alcohol spectrum disorders (FASDs) and sudden infant death syndrome (SIDS). The effects of FASD range from mild to severe and may include intellectual and developmental disabilities; behavior problems; abnormal facial features; and disorders of the heart, kidneys, bones, and auditory system. Women who drink are also more likely to have a miscarriage or stillbirth. Currently, research shows that there is no safe amount of alcohol to drink while pregnant.
• Tobacco use: Smoking during pregnancy puts the fetus at risk for preterm birth, certain congenital anomalies, and SIDS. Smoking and exposure to secondhand smoke during pregnancy can cause changes in an infant’s immune system and puts a woman and her developing fetus at increased risk for health problems.
• Drug use: Smoking marijuana and using illicit drugs during pregnancy can harm the fetus. Research indicates that smoking marijuana and/or using illegal drugs doubled the risk of stillbirth. Research also shows that smoking marijuana during pregnancy can interfere with normal brain development in the fetus, possibly causing long-term health problems.
• Social determinants of health (SDOH): SDOH such as poverty, housing instability, transportation barriers, lack of access to adequate health care, food insecurity, poor health literacy, and psychosocial stressors contribute to poor pregnancy outcomes. These factors are compounded by rural and ethnic disparities and increase the risk for complications such as preeclampsia, preterm birth, intrauterine growth restriction, and miscarriage.^[8],[9]

Conditions of Pregnancy

Several conditions occurring during pregnancy can cause a high-risk pregnancies^[10]:

• Multiple gestation: Pregnancy with twins, triplets, or more fetuses, called multiple gestation, increases the risk of premature labor (i.e., before 37 weeks of pregnancy). Multiple gestation fetuses are more likely to be smaller for gestational size than single infants, and if born prematurely, they are more likely to have difficulty breathing.
• Gestational diabetes: Gestational diabetes occurs when a woman who didn’t have diabetes before develops elevated blood glucose levels while pregnant. Gestational diabetes can cause complications for the mother and fetus, including high blood pressure, preterm labor, and large-for-gestational size that can cause complications during delivery. Gestational diabetes also increases the risk that the woman and her baby will develop type 2 diabetes later in life.
• Preeclampsia and eclampsia: Preeclampsia is a sudden increase in a pregnant woman’s blood pressure after the 20th week of pregnancy. It can affect the mother’s kidneys, liver, and brain and cause long-term health problems. Eclampsia is a severe form of preeclampsia that includes seizures and can cause maternal or fetal mortality.
• Previous preterm birth or short pregnancy interval: Women with a previous preterm labor or childbirth are at higher risk for preterm labor and birth with their current pregnancy. In addition, women who become pregnant less than 12 months after their previous childbirth may be at increased risk for preterm birth.
• Congenital anomalies or genetic conditions in the fetus: In some cases, health care providers can detect congenital anomalies or genetic conditions in the fetus during pregnancy. Depending on the nature of the problems, the pregnancy may be considered high risk because treatments are performed while the fetus is still in the womb or immediately after birth. For example, certain forms of spina bifida can be repaired before birth. Certain heart problems common among infants with Down syndrome are surgically corrected immediately after birth. Being aware of congenital anomalies or genetic conditions before birth can help health care providers and parents be prepared to provide immediate treatment.
• Mental health conditions: Pregnant women may experience mental health conditions, such as depression and anxiety. These conditions are known as perinatal mental health conditions.

Treatment for High-Risk Pregnancy

Treatment for high-risk pregnancy depends on the woman’s specific risk factors. In high-risk pregnancies, the health care provider closely monitors the woman and fetus to detect potential complications as quickly as possible so that treatment can be initiated to reduce risk of morbidity or mortality. Specialized care by a multidisciplinary team of maternal-fetal specialists may be required.

The remaining sections of this chapter will discuss a variety of conditions related to high-risk pregnancies.