Although as of 2004 there was no formal or universally accepted definition of a "high-risk" pregnancy, it is generally thought of as one in which the mother or the developing fetus has a condition that places one or both of them at a higher-than-normal-risk for complications, either during the pregnancy (antepartum), during delivery (intrapartum), or following the birth (postpartum).
Certain conditions, called risk factors, make a pregnancy high risk. Maternal conditions can be identified with preconception counseling and from the maternal history. Maternal physical and social characteristics that can contribute to a high-risk pregnancy include:
- age younger than 15 years and older than 35 years
- pre-pregnancy weight under 100 lbs (45 kg) or obesity
- height under 5 ft (1.5 m)
- incompetent cervix
- uterine malformations
- small pelvis
- being a single woman
- being a smoker
- using illicit drugs
- having no access to early prenatal care
- using alcohol
- having low socioeconomic status
For women who do not have health insurance, obtaining early prenatal care is extremely difficult, and these same women are often from a socioeconomic level that prevents adequate or appropriate nutritional intake. There is a scoring system that can be used by healthcare professionals to determine the degree of risk for a pregnant woman, but it is difficult to rate risk by degrees. Nevertheless, identification of a high-risk pregnancy helps to ensure that those women who need the most care receive it.
One of the initial factors to consider when evaluating risk is the obstetrical history. If this is not the woman's first pregnancy, outcomes of her previous pregnancies are of importance in relation to the outcome of this one. An obstetrical history with any of the following conditions would be considered high risk:
- previous stillbirth
- previous neonatal death
- previous premature infant
- previous post-term (over 42 weeks) pregnancy
- fetal blood transfusion for hemolytic disease
- repeated miscarriages
- previous infant over 10 lbs (4.5 kg)
- six or more completed pregnancies
- history of preeclampsia
- history of eclampsia
- previous cesarean section
- history of a fetus with anomalies
Next to be considered is the medical history factor. A pregnant woman with any of the following medical conditions would be considered at risk:
- abnormal PAP test
- chronic hypertension
- heart disease (class II-IV, symptomatic)
- insulin-dependent diabetes
- moderate to severe kidney disease
- endocrine gland removal or ablation by autoimmune disease
- sickle cell disease
- history of tuberculosis
- positive serology for syphilis
- pulmonary disease
- thyroid disease
- family history of diabetes
- other chronic diseases
- autoimmune diseases, such as lupus
Current pregnancy risk factors would be considered as follows:
- abnormal fetal position
- mild to severe preeclampsia
- multiple pregnancy
- placenta abruption
- placenta previa
- polyhydramnios or oligiohydramnios
- gestational diabetes
- kidney infection
- Rh sensitization only
- mild (>9g/dl hemoglobin) or severe (<9g/dl hemoglobin) anemia
- vaginal spotting
- bladder infection
- emotional problems
- moderate alcohol use
- smoking more than one pack per day
- infection with parvovirus B19 (fifth disease), cytomegalovirus (CMV), toxoplasmosis , listeria, rubella
- exposure to damaging medications, esp., phenytoin, folic acid antagonists, lithium, streptomycin, tetracycline, warfarin
If prenatal testing indicates the baby has a serious congenital anomaly as a heart defect or spinal cord defect, the mother may need additional testing to determine the extent of the problem. Certain maternal or fetal problems may require the physician to deliver a baby early or to choose a surgical delivery (cesarean section) rather than a vaginal delivery.
Most women will see one healthcare provider during pregnancy, either an obstetrician, a midwife, or a nurse practitioner. Women who have a medical problem may need to see a medical specialist as well. Women diagnosed with a high-risk pregnancy should seek the care of an expert in the field of high-risk obstetrics, called a perinatologist. Perinatologists have additional training beyond the education required for an obstetrician. They care for women who have pre-existing medical problems, women who develop complications during pregnancy, and women whose fetus has problems.
Labeling a woman with the diagnosis of high-risk pregnancy requires that one of the previous conditions be met. Thus, the diagnosis may be determined during history taking or if it is the fetus, during the morphological ultrasound at 16–19 weeks gestation. A woman with a high-risk pregnancy will need closer monitoring than pregnant women who are not high risk. Such monitoring may include frequent visits with the primary caregiver, tests to monitor the medical problem, blood tests to check the levels of medication, amniocentesis , serial ultrasound examination, and fetal monitoring. These tests are designed to follow the original condition, survey for complications, verify that the fetus is growing adequately, and make decisions regarding whether labor may need to be induced for early delivery of the fetus.
Treatment varies widely with the type of disease, the effect that pregnancy has on the disease, and the effect that the disease has on pregnancy. If it is the fetus that has a problem, serial ultrasounds may be performed. Fetal heart rate monitoring may be necessary, or amniocentesis may be required. In addition, it may be essential to give the mother medications to act on the baby.
The prognosis is usually dependent on the specific medical condition. Some medical conditions make it difficult for women to get pregnant and lead to a higher risk of problems in the baby. In thyroid disease, the thyroid gland (located in the neck) may produce too much or too little thyroid hormone. Abnormal levels of this hormone can affect fertility and/or cause problems with the pregnancy and possibly affect the health of the baby. Fortunately, thyroid disease can be treated with medication. As long as the level of thyroid hormone is controlled throughout pregnancy, there should be no problems for mother or baby.
There are other medical conditions that do not interfere with pregnancy but are themselves affected by pregnancy. This group includes asthma , epilepsy, and ulcerative colitis. Some women with ulcerative colitis experience a worsening of their symptoms during pregnancy, while others will have no change or may get better during pregnancy. The same is true of asthma: some women notice that their asthma symptoms are better during pregnancy, some find their asthma worse, and some women notice no change in symptoms. It is not immediately apparent why this discrepancy occurs, but due to the unpredictability of diseases, all women with chronic illnesses should be monitored throughout the course of a pregnancy.
Some autoimmune diseases constitute a group of medical conditions that have a major impact on
Ablation —To remove or destroy tissue or a body part, such as by burning or cutting.
Amniocentesis —A procedure performed at 16–18 weeks of pregnancy in which a needle is inserted through a woman's abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby for analysis. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus.
Amniotic sac —The membranous sac that contains the fetus and the amniotic fluid during pregnancy.
Antepartum —The time period of the woman's pregnancy from conception and onset of labor.
Cytomegalovirus (CMV) —A common human virus causing mild or no symptoms in healthy people, but permanent damage or death to an infected fetus, a transplant patient, or a person with HIV.
Eclampsia —Coma and convulsions during or immediately after pregnancy, characterized by edema, hypertension, and proteinuria.
Endocrine —Refers to glands that secrete hormones circulated in the bloodstream or lymphatic system.
Gestational diabetes —Diabetes of pregnancy leading to increased levels of blood sugar. Unlike diabetes mellitus, gestational diabetes is caused by pregnancy and goes away when pregnancy ends. Like diabetes mellitus, gestational diabetes is treated with a special diet and insulin, if necessary.
Intrapartum —Refers to labor and delivery.
Listeria —An uncommon food-borne, life-threatening pathogen that can cause perinatal infection, which is associated with a high rate of fetal loss (including full-term stillbirths) and serious neonatal disease.
Oligohydramnios —A reduced amount of amniotic fluid. Causes include non-functioning kidneys and premature rupture of membranes. Without amniotic fluid to breathe, a baby will have underdeveloped and immature lungs.
Parvovirus B19 —A virus that commonly infects humans; about 50 percent of all adults have been infected sometime during childhood or adolescence. Parvovirus B19 infects only humans. An infection in pregnancy can cause the unborn baby to have severe anemia and the woman may have a miscarriage.
Perinatal —Referring to the period of time surrounding an infant's birth, from the last two months of pregnancy through the first 28 days of life.
Phenytoin —An anti-convulsant medication used to treat seizure disorders. Sold under the brand name Dilantin.
Polyhydramnios —A condition in which there is too much fluid around the fetus in the amniotic sac.
Postpartum —After childbirth.
Preeclampsia —A condition that develops after the twentieth week of pregnancy and results in high blood pressure, fluid retention that doesn't go away, and large amounts of protein in the urine. Without treatment, it can progress to a dangerous condition called eclampsia, in which a woman goes into convulsions.
Premature labor —Labor beginning before 36 weeks of pregnancy.
Rubella —A mild, highly contagious childhood illness caused by a virus; it is also called German measles. Rubella causes severe birth defects (including heart defects, cataracts, deafness, and mental retardation) if a pregnant woman contracts it during the first three months of pregnancy.
Streptomycin —An antibiotic used to treat tuberculosis.
Tetracycline —A broad-spectrum antibiotic.
Toxoplasmosis —A parasitic infection caused by the intracellular protozoan Toxoplasmosis gondii . Humans are most commonly infected by swallowing the oocyte form of the parasite in soil (or kitty litter) contaminated by feces from an infected cat; or by swallowing the cyst form of the parasite in raw or undercooked meat.
Warfarin —An anticoagulant drug given to treat existing blood clots or to control the formation of new blood clots. Sold in the U.S. under the brand name Coumadin.
pregnancy. Women with lupus (a disease caused by alterations in the immune system that result in inflammation of connective tissue and organs) or kidney disease face serious risks during pregnancy. Pregnancy can cause their symptoms to worsen significantly and lead to severe complications for the mother and the baby. With systemic autoimmune diseases or vasculitis, the mother's blood circulation can be impaired and thus the ability to supply oxygen and nutrients to the baby through the placenta is affected. As a result, fetal intrauterine growth becomes restricted (IUGR). Since chronic hypertension or pregnancy-induced hypertension (preeclampsia, eclampsia) similarly affect blood circulation to the placenta, women with these problems are also at risk for IUGR. If the condition is not determined early enough to provide constant monitoring, there is increased risk of stillbirth. Other autoimmune diseases, (antiphospholipid antibody, APA; anticardiolipin antibody, ACLA) are associated with miscarriages.
Diabetes is a medical condition that is affected by pregnancy and, likewise, affects pregnancy. Diabetes can lead to miscarriages, birth defects, and stillbirths. Women with diabetes should have preconception counseling with a perinatologist. Birth defects can result from the variation in a woman's blood sugar level during the first eight to 12 weeks, which is the time period when the embryo is developing. Cardiac defects are not unusual in the babies of women with abnormal blood sugars during that time. Insulin requirements vary tremendously during pregnancy due to placenta hormones that may inhibit the action of insulin. A perinatologist who specializes in diabetes is well aware of what the pregnant woman needs in each trimester and usually recommends the use of an insulin pump for better control. Women with symptomatic cardiac disease face one of the biggest challenges in pregnancy.
Before the advent of perinatology training, women with medical problems such as chronic hypertension, diabetes, and epilepsy were advised to not get pregnant because they could die. With the advancement of technology, it is in the early 2000s possible for these women to have a baby with just a modicum of risk.
Women who have health problems and start specific care before conception have the best chance of a healthy pregnancy. A pre-pregnancy visit with a healthcare provider is, therefore, of the utmost importance for a woman with a medical problem. Together, the perinatologist and the woman can start therapies that will improve the woman's health prior to conception. There may be medications that are safer to take during pregnancy, and the physician can discuss how other women with a specific condition fare during pregnancy. For some diseases, pregnancy can mean increased risk of health problems for mother and baby. In fact, with lupus, preconception counseling is essential to determine the optimum time period for getting pregnant, which is when the disease is in remission. The bottom line is that a woman must always weigh the risks to herself and the baby when deciding whether or not to become pregnant and she can only do this by becoming informed.
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American College of Obstetricians and Gynecologists. 409 12th Street, SW, PO Box 96920, Washington, DC 20090. Web site: http://www.acog.org.
Association of Women's Health, Obstetric and Neonatal Nursing. 2000 L Street, NW Suite 740, Washington, DC 20036. Web site: <www.awhonn.org.
Linda K. Bennington, MSN, CNS