5.5: Disorders of Pregnancy

5.5.1 Infections that affect pregnancy & fetal development

The following information is courtesy of Eunice Kennedy Shriver National Institute of Child Health and Human Development.⁵³

5.5.1.1 Bacterial Vaginosis

Bacterial vaginosis is the most common vaginal infection in women of reproductive age. It increases the risk of contracting sexually transmitted infections (STIs) and may play a role in preterm labor. The condition results from a change in the balance of bacteria that normally live in the vagina. Having unprotected sex and douching can increase the risk of bacterial vaginosis. The Centers for Disease Control and Prevention (CDC) recommends that pregnant women get tested for bacterial vaginosis if they have symptoms and get treated if necessary.

5.5.1.2 Chlamydia

Chlamydia infection during pregnancy is associated with an increased risk of preterm birth and its complications. If the infection is present and untreated at the time of delivery, it can lead to eye infections or pneumonia in the infant.² In most hospitals, infants' eyes are routinely treated with an antibiotic ointment shortly after birth. The ointment can prevent blindness from exposure to chlamydia bacteria during delivery in case the pregnant woman had an undetected infection.

5.5.1.3 Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is a common virus present in many body fluids that can be spread through close personal contact, such as kissing or sharing eating utensils, as well as sexual contact. The virus usually does not cause health problems, but once it is in a person's body, it stays there for life and can reactivate at different times. A pregnant woman may not even know she has the infection, and she may pass the virus on to her fetus, causing congenital CMV infection. Most infants with congenital CMV infection never show signs or have health problems. However, some infants have health problems such as hearing or vision loss, seizures, or intellectual disabilities that are apparent at birth or that develop later during infancy or childhood. Currently, routine screening for CMV during pregnancy is not recommended. Researchers are working on treatments for CMV and vaccines to try to prevent new infections during pregnancy and to reduce the risk of transmission to the infant. Congenital CMV infection can be diagnosed by testing a newborn baby's saliva, urine, or blood. Treatment with antiviral drugs may decrease the risk of health problems and hearing loss in some infected infants.

5.5.1.4 Fifth Disease

Fifth disease is caused by human parvovirus type B19. The virus causes a common childhood disease that spreads easily from person to person. Children who get it usually have a fever and a red rash on their cheeks. Parvovirus B19 usually does not cause problems for a pregnant individual or the fetus, but in rare cases, there might be a miscarriage, or the fetus could develop anemia. There is no vaccine or treatment for fifth disease. You can reduce your chance of being infected with parvovirus B19 or infecting others by avoiding contact with people who have parvovirus B19 and by thoroughly and regularly washing your hands. Sometimes health care providers recommend testing pregnant individuals to see if they are immune to the virus already.

5.5.1.5 Gonorrhea

Untreated gonorrhea infection in pregnancy has been linked to miscarriage, preterm birth and low birth weight, premature rupture of the membranes surrounding the fetus in the uterus, and infection of the fluid that surrounds the fetus during pregnancy. Gonorrhea can also infect an infant during delivery as it passes through the birth canal. If untreated, infants can develop eye infections and blindness. In most hospitals, infants' eyes are routinely treated with an antibiotic ointment shortly after birth to prevent eye problems from exposure to gonorrhea during delivery, in case the pregnant woman had an undetected infection. Treating gonorrhea as soon as it is detected in pregnant individuals reduces the risk of transmission.

5.5.1.6 Group B Streptococcus (GBS)

Group B streptococcus (GBS) can cause serious health problems in infants. But giving antibiotics during labor can prevent the spread of GBS, so it's important to get tested for the infection during pregnancy.

For more information

More information about GBS and pregnancy can be found at the CDC "About Group B Strep Disease."

5.5.1.7 Genital Herpes

Pregnant women who get infected with genital herpes late in pregnancy have a high risk of infecting their fetus. The risk of infection is particularly high during delivery. Herpes infections in newborns are serious and potentially life-threatening. Infection with the herpes virus during pregnancy or at the time of delivery can lead to brain damage, blindness, and damage to other organs. Rarely, herpes infection during pregnancy can lead to serious complications in the mother, including severe liver damage and possibly death.

• If a pregnant woman has had genital herpes in the past, there are medications that she can take to reduce the chance that she will have an outbreak, which also reduces the risk to her fetus.
• If an individual has active herpes sores when they go into labor, the infant can be delivered by cesarean section to reduce the chance that the infant will come in contact with the virus.

5.5.1.8 Hepatitis B (HBV) & Hepatitis C (HCV)

If a woman is infected with hepatitis B virus (HBV) during pregnancy, the virus could infect her fetus. The likelihood of transmission depends on when during pregnancy the mother was infected. If the mother gets the infection later in her pregnancy, the risk that the virus will infect her fetus is quite high. If the infection occurs early in pregnancy, the risk of the virus infecting the fetus is much lower. In infants, HBV can be serious and can lead to chronic liver disease or liver cancer later in life. In addition, infected newborns have a very high risk of becoming carriers of HBV and can spread the infection to others.

• In some cases, if a woman is exposed to HBV during pregnancy, she may be treated with a special antibody to reduce the likelihood that she will get the infection.
• All healthy infants should be vaccinated against HBV to give them lifelong protection.
• Infants born to women with evidence of ongoing HBV infection (HBV surface antigen positive) should also receive hepatitis B hyperimmune globulin as soon as possible after birth.

Hepatitis C virus (HCV). If a pregnant individual is infected with HCV during pregnancy, the virus could infect the fetus.

For more information

More information about Hep B during pregnancy can be found from the Centers for Disease Control and Prevention (CDC).

More information about HCV can be found from the CDC.

Hepatitis C virus (HCV). If a pregnant individual is infected with HCV during pregnancy, the virus could infect the fetus. More information from CDC about HCV can be found online.

5.5.1.9 HIV/AIDS

HIV/AIDS. HIV can be passed from mother to infant during pregnancy before birth, at the time of delivery, or after birth during breastfeeding.

5.5.1.10 Listeria

Listeria or listeriosis is a serious infection usually caused by eating food contaminated with a particular type of bacteria. Infection during pregnancy can lead to pregnancy loss, stillbirth, preterm birth, or life-threatening infection of the newborn. Listeriosis is most often associated with eating soft cheeses and raw milk, but recent outbreaks have been associated with fresh and frozen produce. Prevention recommendations include checking food labels to avoid eating unpasteurized cheese (made from raw milk) and other actions. Learn more about preventing listeria during pregnancy.

5.5.1.11 Rubella

Getting rubella (sometimes called German measles) during pregnancy can cause problems with the pregnancy as well as birth defects in the infant. Health care providers recommend that individuals get vaccinated against rubella before they get pregnant. Learn more about rubella and pregnancy.

5.5.1.12 Syphilis

Syphilis may pass from an infected pregnant individual to their fetus during pregnancy. The infection has been linked to preterm birth, stillbirth, and, in some cases, death shortly after birth. Untreated infants who survive tend to develop problems in many organs, including the brain, eyes, ears, heart, skin, teeth, and bones. All pregnant individuals should be screened for syphilis during their first prenatal visit. Pregnant individuals considered to be high risk should be screened again in the third trimester.

5.5.1.13 Toxoplasmosis

Toxoplasmosis is a disease caused by a parasite that can be present in cat feces or used cat litter. Cats get the parasite from eating small animals or birds. In humans, the disease is usually mild, but if the parasite passes from a pregnant individual to the developing fetus, it can cause intellectual disabilities, blindness, or other problems. Individuals who are trying to become pregnant or are pregnant can take steps to prevent exposure to the parasite, such as having someone else clean or change the cat litter box and wearing rubber gloves to handle cat litter or while gardening.

5.5.1.14 Trichomoniasis

Trichomoniasis is a common sexually transmitted infection, caused by a protozoan parasite. Pregnant individuals with trichomoniasis are more likely to deliver their baby prematurely and to have a baby with a low birth weight.

For more information

More information about trichomoniasis can be found from the CDC.

5.5.1.15 Zika

Zika is caused by a virus spread mainly by the bite of a certain type of mosquito, but it is also spread through sexual contact. Although its symptoms are usually mild, Zika infection during pregnancy can cause pregnancy loss and other pregnancy complications, as well as birth defects and other problems for the infant.

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5.5.2 Meconium Aspiration

Throughout the second half of gestation, the fetal intestines accumulate a tarry, greenish black meconium. The newborn’s first stools consist almost entirely of meconium; they later transition to seedy yellow stools or slightly formed tan stools as meconium is cleared and replaced with digested breast milk or formula, respectively. Unlike these later stools, meconium is sterile; it is devoid of bacteria because the fetus is in a sterile environment and has not consumed any breast milk or formula. Typically, an infant does not pass meconium until after birth. However, in 5–20 percent of births, the fetus has a bowel movement in utero, which can cause major complications in the newborn.⁵⁴

The passage of meconium in the uterus signals fetal distress, particularly fetal hypoxia (i.e., oxygen deprivation). This may be caused by maternal drug abuse (especially tobacco or cocaine), maternal hypertension, depletion of amniotic fluid, long labor or difficult birth, or a defect in the placenta that prevents it from delivering adequate oxygen to the fetus. Meconium passage is typically a complication of full-term or post-term newborns because it is rarely passed before 34 weeks of gestation, when the gastrointestinal system has matured and is appropriately controlled by nervous system stimuli. Fetal distress can stimulate the vagus nerve to trigger gastrointestinal peristalsis and relaxation of the anal sphincter. Notably, fetal hypoxic stress also induces a gasping reflex, increasing the likelihood that meconium will be inhaled into the fetal lungs.⁵⁵

Although meconium is a sterile substance, it interferes with the antibiotic properties of the amniotic fluid and makes the newborn and pregnant person more vulnerable to bacterial infections at birth and during the perinatal period. Specifically, inflammation of the fetal membranes, inflammation of the uterine lining, or neonatal sepsis (infection in the newborn) may occur. Meconium also irritates delicate fetal skin and can cause a rash.⁵⁶

The first sign that a fetus has passed meconium usually does not come until childbirth, when the amniotic sac ruptures. Normal amniotic fluid is clear and watery, but amniotic fluid in which meconium has been passed is stained greenish or yellowish.⁵⁷

Aspiration of meconium with the first breath can result in labored breathing, a barrel-shaped chest, or a low Apgar score. An obstetrician can identify meconium aspiration by listening to the lungs with a stethoscope for a coarse rattling sound. Blood gas tests and chest X-rays of the infant can confirm meconium aspiration. Inhaled meconium after birth could obstruct a newborn’s airways leading to alveolar collapse, interfere with surfactant function by stripping it from the lungs, or cause pulmonary inflammation or hypertension. Any of these complications will make the newborn much more vulnerable to pulmonary infection, including pneumonia.⁵⁸

For more information

More information about antepartum infections can be found in NLM StatPearls "Antepartum Infections."

5.5.3 Hypertensive Disorders

5.5.3.1 Preeclampsia and Eclampsia

The following information is courtesy of Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Preeclampsia and eclampsia are pregnancy-related high blood pressure disorders. In preeclampsia, the pregnant person’s high blood pressure reduces the blood supply to the fetus, which may get less oxygen and fewer nutrients. Eclampsia is when an individual with preeclampsia develops seizures or coma. Preeclampsia and eclampsia are part of the spectrum of high blood pressure, or hypertensive, disorders that can occur during pregnancy. The condition can be serious and is a leading cause of preterm birth (before 37 weeks of pregnancy).⁵⁹

For more information

Watch Video 5.1 -Preeclampsia (courtesy of MedlinePlus.gov)

More information about preeclampsia can be found online in NLM StatPearls "Preeclampsia."

5.5.4 Gestational Diabetes

The following information is courtesy of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

During pregnancy, the placenta releases lactogen. Lactogen reduces the normal function of insulin. This results in glucose in the blood rather than glucose going into the cells (insulin resistance). The body responds to this by producing more insulin. But some individuals are not able to make enough insulin to overcome the insulin resistance. These individuals develop gestational diabetes.

Gestational diabetes can cause an increased chance of having miscarriage or a stillborn baby. It is also more likely that the baby will be born prematurely or weigh too much, which can make delivery difficult and may increase the chance of having a cesarean section. People with gestational diabetes are also more likely to develop preeclampsia.

Usually, a person with gestational diabetes has no symptoms. Sometimes the symptoms are mild, such as being thirstier than normal or having to urinate more often. Testing for gestational diabetes usually occurs between 24 and 28 weeks of pregnancy and is diagnosed at that time. A blood test is used to determine how well the body uses glucose.

Some individuals with gestational diabetes can manage their blood glucose levels by following a healthy eating plan and being physically active. Some also may need insulin or other medications.

For more information

More information about insulin and gestational diabetes can be found in NLM StatePearls "Gestational Diabetes."

5.5.5 Preterm and Postterm Labor

Labor that begins before 37 weeks is called preterm labor (or premature labor). A birth that occurs before 37 weeks is considered a preterm birth. Preterm birth is the most common cause of infant death and is the leading cause of long-term disability related to the nervous system in children. Individuals with symptoms of preterm labor should go to the hospital immediately.

The causes of preterm labor and premature birth are numerous, complex, and only partly understood. Medical, psychosocial, and biological factors may all play a role in preterm labor and birth. There are a number of risk factors for preterm birth, including being pregnant with twins, triplets, or more.

Treatment varies depending upon the gestational age and stage of labor and starts with monitoring for fetal health and signs and symptoms of preterm labor. In some cases, patients are given medications that delay and suppress the contraction of the smooth muscle of the uterus. Delayed umbilical cord clamping results in better long-term outcomes for premature infants.60 More information about premature labor can be found online.

Post-term pregnancy is any pregnancy that extends beyond 42 weeks gestation. There is an increased risk of the baby being stillborn in a post-term pregnancy. Studies indicate that induction of labor by week 41 is associated with better outcomes for parent and child.⁶¹

5.5.6 Complications with Twins

Twin-to-twin transfusion syndrome (CTS) is a rare condition that occurs during pregnancy with identical twins. Abnormal vasculature in the placenta results in one twin receiving less blood (donor) than the other twin (recipient). The donor twin may have poor growth, anemia, and dehydration. The recipient twin may be larger, with too much blood, and increased blood pressure, and an increased risk for heart failure. Untreated, this situation can be fatal for both twins. Once identified, the amount of amniotic fluid and pressure can be decreased and/or a laser can be used to close the abnormal vessels in the placenta.

For more information

Watch Video 5.2 - Twin-to-Twin Transfusion Syndrome (courtesy of MedlinePlus.gov)

More information about TTTS can be found in NLM StatPearls "Twin-to-twin Transfusion Syndrome."

Footnotes

53. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). "What infections can affect pregnancy?" (2017). Available from NICHD
54. Betts, J. Gordon, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix. "Fetal Development." Chapter 28.3 in Anatomy and Physiology. (2013). Open Stax, 2013 This work is distributed under a CC BY 4.0 license. Available from Open Stax
55. Betts et al, 2013, 28.3
56. Betts et al, 2013, 28.3
57. Betts et al, 2013, 28.3
58. Betts et al, 2013, 28.3
59. Goldenberg, Robert L, Jennifer F Culhane, Jay D Iams, and Roberto Romero. "Epidemiology and Causes of Preterm Birth." The Lancet 371, no. 9606 (Jan 2008):75–84. DOI: 10.1016/S0140-6736(08)60074-4 PMID: 18177778 PMCID: PMC7134569 Open Access, available from The Lancet
60. Tarnow-Mordi, William, Jonathan Morris, Adrienne Kirby, et al. "Delayed Cord Clamping in Preterm Infants." New England Journal of Medicine 377, no. 25 (2017): 2445-2455. DOI: 10.1056/NEJMoa1711281 PMID: 29081267
61. Galal, M.,I Symonds, H Murray, F Petraglia, and Smith, R. "Postterm Pregnancy." Facts, Views & Vision ObGyn 4, no. 3 (2012): 175–187. PMID: 24753906 PMCID: PMC3991404