Pregnancy complications

What are pregnancy complications?

Pregnancy complications are health problems that occur during pregnancy, and which affect the mother, the baby or both. The majority of pregnancies proceed normally without any health issues, but it is important, even for very healthy women, to be aware of possible complications. Familiarity with possible kinds of pregnancy complications and their symptoms will contribute to the likelihood of a healthy pregnancy by enabling the expectant parent to:

  • Ensure that any necessary preventive measures are taken
  • Identify potential complications early enough to treat them successfully
  • Receive appropriate healthcare support should it be needed

This will increase the possibility of preventing pregnancy complications that do occur resulting in adverse outcomes, such as miscarriage.

The following overview of possible pregnancy complications includes some of the most common pregnancy complications, including:

  • Infections that may develop during pregnancy
  • Non-infectious conditions, possibly pre-existing, which can present complications during pregnancy
  • Complications that are specific to pregnancy

Infections during pregnancy

During pregnancy, women are more susceptible to certain infections and the complications of certain infections. Some infections may also affect the healthy development of the baby.

Chickenpox during pregnancy

The likelihood of developing chickenpox during pregnancy is relatively low, and women who do contract chickenpox are unlikely to experience serious complications. However, in some cases, chickenpox during pregnancy can cause complications for the mother and baby and be potentially life threatening.[1]

Contact a doctor or midwife in the following situations:

  • Chickenpox is contracted, or there is a suspicion of the condition
  • The mother has never had chickenpox and never been near anyone with chickenpox, even if there are no symptoms present

Food poisoning during pregnancy

Pregnant women are more likely to develop food poisoning. In most cases, a bout of food poisoning will be unpleasant for the mother, but will not affect the health of the baby. However, food poisoning can affect the baby, especially if the infection is a result of types of bacteria called listeria, which causes listeriosis, or the toxoplasma gondii parasite, which causes toxoplasmosis.

  • Listeriosis is a bacterial infection, often found in unpasteurised dairy products, such as milk and soft cheeses, as well as raw and cured (deli) meats. It is important to avoid these foods during pregnancy and to contact one’s doctor or midwife at the first sign of infection, which may include nausea and vomiting, diarrhoea and/or aches and pains. Diagnosis will be made with a blood test, after which a course of antibiotic treatment will usually be prescribed to prevent possible pregnancy complications. Pregnant women are particularly susceptible to Listeria infection in their third trimester.[2]
  • Toxoplasmosis is a parasite infection, often found in raw or undercooked meat, cat feces and contaminated soil. If a pregnant woman develops toxoplasmosis, this can pose serious health risks for the baby, including miscarriage and stillbirth.[3] The likelihood of contracting toxoplasmosis during pregnancy is thought to be very small, but pregnant women should nonetheless take care to wash their hands thoroughly with antibacterial soap and water after touching soil, for example, after gardening, and avoid undercooked meat, raw shellfish, unfiltered water and possibly contaminated fruits and vegetables. It would also be prudent to ask another individual to change the cat litter box, should this be necessary. Preventive measures are the most appropriate in combating toxoplasmosis.[4]
    A pregnant woman may develop no symptoms at all as a result of toxoplasmosis or may feel generally unwell and develop swollen glands.[5] If there is any concern that a pregnant woman may have contracted the infection, even when no symptoms are present, urgent medical attention should be sought.

Contact a doctor or midwife in the following situations, which may relate to food poisoning:[3]

  • The mother feels very unwell, particularly if there is severe stomach pain
  • There is a fever
  • Diarrhea lasts for longer than three days
  • Vomiting is continuous
  • The mother cannot keep fluids down
  • There is blood in the mother’s stool
  • There is bleeding from the vagina

For more information about avoiding food poisoning, consult these resources on foods to eat during pregnancy and foods to avoid during pregnancy.

Flu during pregnancy

The chances of complications are higher for women who contract the flu during pregnancy, but for most, these will not be serious. In some cases, these complications can affect the baby’s health.

Pregnant women are advised to have the flu vaccine to lower the chances of contracting the viral infection. Other preventive measures – such as avoiding contact with people with the flu and washing the hands regularly – should also be taken throughout the course of the pregnancy.

The flu typically begins with the following symptoms:

  • Achiness and fatigue
  • Fever
  • Cold symptoms (coughing, sore throat, runny or stuffy nose, sneezing, etc)

A doctor should be contacted as a matter of urgency if the following symptoms present themselves:[6]

  • Shortness of breath or difficulty breathing
  • There is blood in the mucus
  • Chest (abdomen) pain
  • Dizziness or confusion
  • Persistent vomiting
  • The mother cannot feel the baby moving as often as previously. This may be a symptom of miscarriage; see this resource on signs of miscarriage for more information).

Erythema infectiosum during pregnancy Parvovirus B19

Erythema infectiosum, also known as fifth disease or slapped cheek syndrome, is a common, non-serious condition caused by parvovirus B19. It is most common in children. Most women are already immune to the virus, making the chances of infection during pregnancy relatively low. However, if contracted during pregnancy, there is a chance that the virus could be passed on to the baby and cause complications, including miscarriage, especially if it develops during the first half of pregnancy.[3]

Pregnant women should seek medical attention urgently if they develop a rash or a high temperature, or if they suspect they have been in contact with others affected by parvovirus B19, even if no symptoms are present. A doctor will be able to screen for the virus, using a blood test, and advise on treatment options thereafter.[7]

Rubella during pregnancy

Rubella is typically a mild, self-limiting condition. If contracted during pregnancy, especially during the first 12 weeks of pregnancy, however, rubella can cause potentially serious harm to the baby. All pregnant women are advised to have the rubella vaccine if they have not received it previously. If an individual is unsure whether they have had the vaccine or not, they should contact a doctor who will be able to check via a blood test.[8] Women who have contracted rubella during pregnancy should be counseled on maternal-fetal transmission and offered a pregnancy termination, especially when the infection is diagnosed prior to 16 weeks’ gestation.[9]

Sexually transmitted diseases and infections during pregnancy

Pregnant women can get the same sexually transmitted diseases (STDs) and infections (STIs) as non-pregnant women. STDs and STIs experienced during pregnancy can result in potentially harmful consequences for both the mother and the baby, making it important for pregnant women to be regularly tested throughout their pregnancy.[10] Following a diagnosis, a doctor will be able to prescribe an appropriate treatment method.

Urinary tract infection (UTI) during pregnancy

Pregnant women are at an increased risk of developing a urinary tract infection (UTI), particularly from week 6 to week 24. If left untreated, a UTI can pose risks to the baby, including premature labor and low birth weight.

A doctor should be contacted should any of the following symptoms occur:[11]

  • Pain or discomfort when urinating
  • Blood or mucus in the urine
  • Stomach cramps
  • Urine leakage
  • Fever

Non-infectious conditions during pregnancy

The following conditions may be pre-existing or develop for the first time during pregnancy. In either case, they may need to be specially managed during pregnancy to prevent complications for the mother or baby.

Anemia during pregnancy

Anemia involves having a low number of healthy red blood cells. Pregnant women face an increased risk of developing anemia because of the large amount of blood their bodies produce to support the growth of the baby. If detected early, anemia poses little risk to the mother or baby but it can pose health risks if left untreated.

If any of the following symptoms appear, medical attention should be sought:[12]

  • Weakness or fatigue
  • Dizziness
  • Shortness of breath
  • Irregular or rapid heartbeat
  • Pain in the chest

See this resource for more information about anemia.

Diabetes and gestational diabetes during pregnancy

Pregnant women who have type 1 or 2 diabetes before becoming pregnant are at risk of various complications affecting both themselves and their babies. These complications include the baby developing health problems after birth, including an increased risk of also developing diabetes. Proper management of the condition is the best way to reduce the risk of complications. Pregnant women, or women planning a pregnancy, should consult their doctor or diabetes specialist for advice on how to do this.[13]

Gestational diabetes is a type of diabetes that can occur as a result of high blood sugar levels during pregnancy. If gestational diabetes is not properly managed, it can cause complications such as high birth weight, premature birth and, in rare cases, stillbirth. Gestational diabetes is normally screened for as standard, and especially so if the pregnant woman is part of one of the groups most at risk of the condition, women who are overweight, for example. If detected, the condition can be managed through lifestyle changes and medication.[14]

High blood pressure (hypertension) during pregnancy

Pregnant women will be regularly screened for high blood pressure. If high blood pressure is detected, it will be mild and easily treated with medication in most cases. If a pregnant woman is already taking medication for high blood pressure, they should be sure to inform their doctor or midwife of this, as pregnancy-appropriate medication may be called for.

In severe cases, untreated high blood pressure can develop into a condition called preeclampsia, which can serious cause harm to the mother and baby.[3] See this resource for more information on the diagnosis and treatment of preeclampsia.

Diseases of the thyroid during pregnancy

Thyroid dysfunction causes the production of too much or too little thyroid hormone, affecting the body’s processes. This can negatively impact the health of pregnant people and their babies, potentially leading to a number of complications if the condition is not effectively managed. These include congenital defects, stillbirth, preterm birth and miscarriage.

See this resource on thyroid and pregnancy for more information.

Obesity during pregnancy

Obesity, defined as having a BMI over 30, during pregnancy, can result in a number of health risks for both mother and baby. Risks associated with obesity include gestational diabetes, preeclampsia and stillbirth, as well as an increased risk of diabetes and obesity in later life for the infant. Obesity can be tackled through weight management – a doctor will be able to offer advice on how to do this in a way that is safe to undertake during pregnancy.[15]

Mental health problems during pregnancy

It is common for pregnant women, including women who have no previous history of mental health problems, to experience mental health problems during pregnancy. These problems can include anxiety and depression and may range from mild to severe. For those experiencing mental health problems, it is important to talk to their doctor or psychiatrist about what they are going through. These professionals will also be able to explain and prescribe treatment options, which may include being referred to a specialist in prenatal mental health or medication, with the treatment choice depending on the severity of symptoms and the individual’s history of mental health.[16]

Complications specific to pregnancy

The following complications are specific to the course of pregnancy.

Placenta praevia

The placenta develops alongside the baby in the womb, connecting the baby to the mother’s blood system and providing it with oxygen and nourishment. Placenta praevia, or low-lying placenta, occurs when the placenta sits low in the uterus and covers part or all of the cervix, the entrance to the womb. In most cases, the placenta will move upwards as the uterus grows larger, though in some women the placenta will remain low-lying in the final stages of pregnancy. The condition will typically be identified through routine scans and monitored throughout the pregnancy. Placenta praevia can lead to bleeding in the second half of pregnancy, which will typically not be accompanied by pain. This bleeding can be heavy and, in severe cases, pose a risk to the baby’s life. The condition, however, is rarely life-threatening, though may require the mother to undergo a cesarean section at birth.[14]

Placental abruption

Placental abruption occurs when the placenta prematurely separates from the inner wall of the womb (uterus) prior to the baby being born. This separation may be partial or total and may cause bleeding from the vagina or concealed bleeding inside the womb, in which case the bleeding will not be obvious to the mother. In these cases, placental abruption will typically be identified through other symptoms, such as stomach pains.[17] In severe cases, the condition can be life-threatening.

If any of the following symptoms appear, a doctor or midwife should be contacted urgently:[18]

  • Bleeding from the vagina
  • Pain in the stomach
  • Back pain
  • Frequent contractions
  • The baby ceases to move as often as previously

Antepartum haemorrhage

Antepartum haemorrhage is bleeding from the birth canal (vagina) after the 24th week of pregnancy. Bleeding before this time results in miscarriage and bleeding, which occurs after the baby has been born, is termed postpartum haemorrhage. In around half of all cases no definite cause of antepartum haemorrhage can be identified. The most important causes of antepartum haemorrhage are placenta praevia and placental abruption, yet they are not the most common. The condition can be life-threatening for the baby, so a doctor should be contacted urgently if any vaginal bleeding occurs.[19]

Ectopic pregnancy

Ectopic pregnancy occurs when a fertilized egg implants itself outside of the womb, typically in one of the fallopian tubes. If this happens, the embryo is unable to develop properly and will usually need to be removed, using medication or a surgical procedure. Ectopic pregnancy can sometimes be symptomless – in these cases, it will only be detected during a routine scan. The following symptoms can, however, present themselves:[20]

  • Stomach pain
  • Bleeding from the vagina
  • Pain in the tip of the shoulder
  • Discomfort when using the bathroom

If any of these symptoms appear, a doctor or midwife should be contacted as a matter of urgency. Note that these symptoms may also be a sign of another condition. See this resource on ectopic pregnancy for more information.

Molar pregnancy

A molar pregnancy, sometimes called a hydatidiform mole, is a rare chromosomally abnormal pregnancy resulting from a problem related to the genetic makeup of the fused egg and sperm, which occurs during conception. This causes a fluid-filled mass of tissue to grow inside the womb instead of a healthy pregnancy. A molar pregnancy will not develop into a baby.

A molar pregnancy will often have the same symptoms as a normal pregnancy in its early stages, and may go undetected until the first routine ultrasound scan, if it is not miscarried before this time. However, symptoms which could indicate a molar pregnancy, include vaginal bleeding, severe nausea and vomiting and tummy growth which is faster than normal.


  1. NHS Choices. “What are the risks of chickenpox during pregnancy?” October 24, 2016. Accessed May 9, 2018.

  2. UpToDate. “Epidemiology and pathogenesis of Listeria monocytogenes infection.” April 17, 2018. Accessed May 30, 2018.

  3. Patient. “Pregnancy Complications.” October 30, 2017. Accessed May 9, 2018.

  4. UpToDate. “Toxoplasmosis and pregnancy.” December 5, 2017. Accessed May 30, 2018.

  5. Patient. “Toxoplasmosis.” October 3, 2016. Accessed May 9, 2018.

  6. Babycenter. “Flu during pregnancy.” Accessed May 9, 2018.

  7. NHS Choices. “What are the risks of slapped cheek syndrome during pregnancy?” November 30, 2015. Accessed May 9, 2018.

  8. NCBI. “Rubella (German measles) during pregnancy.” November, 2007. Accessed May 9, 2018.

  9. UpToDate. “Rubella in pregnancy.” November 20, 2017. Accessed May 30, 2018.

  10. CDC. “STDs during Pregnancy - CDC Fact Sheet.” Accessed May 9, 2018.

  11. American Pregnancy Association. “Urinary Tract Infection During Pregnancy.” March 10, 2017. Accessed May 9, 2018.

  12. American Pregnancy Association. “Anemia During Pregnancy.” October 16, 2016. Accessed May 9, 2018.

  13. NHS Choices. “Diabetes and pregnancy.” April 12, 2018. Accessed May 9, 2018.

  14. NHS Choices. “Gestational diabetes.” August 5, 2016. Accessed May 9, 2018.

  15. NCBI. “The Impact of Maternal Obesity on Maternal and Fetal Health.” 2008. Accessed May 9, 2018.

  16. NHS Choices. “Mental health problems and pregnancy.” April 4, 2018. Accessed May 9, 2018.

  17. BMJ Best Practice. “Placental abruption.” February, 2018. Accessed May 10, 2018.

  18. Babycentre. “Placental abruption.” April, 2015. Accessed May 10, 2018.

  19. Patient. “Antepartum haemorrhage.” March 11, 2016. Accessed May 10, 2018.

  20. NHS Choices. “Ectopic pregnancy.” February 3, 2016. Accessed May 10, 2018.