What are some common complications of pregnancy?

High blood pressure, also called hypertension, occurs when arteries carrying blood from the heart to the body organs are narrowed. This causes pressure to increase in the arteries. In pregnancy, this can make it hard for blood to reach the placenta, which provides nutrients and oxygen to the fetus.¹ Reduced blood flow can slow the growth of the fetus and place the mother at greater risk of preterm labor and preeclampsia.^1,2

Women who have high blood pressure before they get pregnant will continue to have to monitor and control it, with medications if necessary, throughout their pregnancy. High blood pressure that develops in pregnancy is called gestational hypertension. Typically, gestational hypertension occurs during the second half of pregnancy and goes away after delivery.

Gestational diabetes occurs when a woman who didn't have diabetes before pregnancy develops the condition during pregnancy.

Normally, the body digests parts of your food into a sugar called glucose. Glucose is your body's main source of energy. After digestion, the glucose moves into your blood to give your body energy.

To get the glucose out of your blood and into the cells of your body, your pancreas makes a hormone called insulin. In gestational diabetes, hormonal changes from pregnancy cause the body to either not make enough insulin, or not use it normally. Instead, the glucose builds up in your blood, causing diabetes, otherwise known as high blood sugar.

Managing gestational diabetes, by following a treatment plan outlined by a health care provider, is the best way to reduce or prevent problems associated with high blood sugar during pregnancy. If not controlled, it can lead to high blood pressure from preeclampsia and having a large infant, which increases the risk for cesarean delivery.⁴

Infections, including some sexually transmitted infections (STIs), may occur during pregnancy and/or delivery and may lead to complications for the pregnant woman, the pregnancy, and the baby after delivery. Some infections can pass from mother to infant during delivery when the infant passes through the birth canal; other infections can infect a fetus during the pregnancy.¹ Many of these infections can be prevented or treated with appropriate pre-pregnancy, prenatal, and postpartum follow-up care.

Some infections in pregnancy can cause or contribute to:¹

• Pregnancy loss/miscarriage (before 20 weeks of pregnancy)
• Ectopic pregnancy (when the embryo implants outside of the uterus, usually in a fallopian tube)
• Preterm labor and delivery (before 37 completed weeks of pregnancy)
• Low birth weight
• Congenital anomalies, including blindness, deafness, bone deformities, and intellectual disability
• Stillbirth (at or after 20 weeks of pregnancy)
• Illness in the newborn period (first month of life)
• Newborn death
• Maternal health complications

If you are planning to get pregnant, talk with your health care provider about getting vaccines and vaccine boosters for chicken pox (also called varicella) and rubella (also called German measles) before you conceive. You can also get some vaccines, such as the flu shot, while you are pregnant. If you know you have an infection, such as an STI, talk with your health care provider about it before you conceive to increase your chances of a healthy pregnancy.

Early prenatal testing for STIs and other infections can determine if the infection can be cured with drug treatment. Or, if you know you have an infection, tell your pregnancy health care provider about it as early as possible in your pregnancy. Early treatment decreases the risk to the fetus and infant.² Even if the infection can't be cured, you and your health care provider can take steps to protect your health and your infant's health.

Learn more about infections that can affect pregnancy.

Preeclampsia is a serious medical condition that can lead to preterm delivery and death. Its cause is unknown, but some women are at an increased risk. Risk factors include:⁵

• First pregnancies⁵
• Preeclampsia in a previous pregnancy⁵
• Existing conditions such as high blood pressure, diabetes, kidney disease, and systemic lupus erythematosus¹
• Being 35 years of age or older¹
• Carrying two or more fetuses¹
• Obesity¹

Preterm labor is labor that begins before 37 weeks of pregnancy. Any infant born before 37 weeks is at an increased risk for health problems, in most cases because organs such as the lungs and brain finish their development in the final weeks before a full-term delivery (39 to 40 weeks).

Certain conditions increase the risk for preterm labor, including infections, developing a shortened cervix, or previous preterm births.⁶

Progesterone, a hormone produced naturally during pregnancy, may be used to help prevent preterm birth in certain women. A 2003 study led by NICHD researchers found that progesterone supplementation to women at high risk for preterm delivery due to a prior preterm birth reduces the risk of a subsequent preterm birth by one third.⁷

Research shows that as many as 13% of U.S. women reported frequent symptoms of depression after childbirth, and that anxiety co-occurs in up to 43% of depressed pregnant and postpartum women, making pregnancy-related depression and anxiety among the more common pregnancy complications.⁸ These medical conditions can have significant effects on the health of the mother and her child. But the good news is that these are treatable medical conditions. The NICHD-led Moms’ Mental Health Matters initiative is designed to educate families and health care providers about who is at risk for depression and anxiety during and after pregnancy, the signs of these problems, and how to get help. 

Miscarriage is the term used to describe a pregnancy loss from natural causes before 20 weeks. Signs can include vaginal spotting or bleeding, cramping, or fluid or tissue passing from the vagina. However, bleeding from the vagina does not mean that a miscarriage will happen or is happening.⁹ Women experiencing this sign at any point in their pregnancy should contact their health care provider.

The loss of pregnancy after the 20th week of pregnancy is called a stillbirth. In approximately half of all reported cases, health care providers can find no cause for the loss. However, health conditions that can contribute to stillbirth include chromosomal abnormalities, placental problems, poor fetal growth, chronic health issues of the mother, and infection. Read more about health conditions and lifestyle factors that can increase the risk for stillbirth.

Other complications of pregnancy may include the following:

• Severe, persistent nausea and vomiting. Although having some nausea and vomiting is normal during pregnancy, particularly in the first trimester, some women experience more severe symptoms that last into the third trimester.
  
  The cause of the more severe form of this problem, known as hyperemesis gravidarum (pronounced HEYE-pur-EM-uh-suhss grav-uh-DAR-uhm), is not known. Women with hyperemesis gravidarum experience nausea that does not go away, weight loss, reduced appetite, dehydration, and feeling faint.¹⁰
  
  Affected women may need to be hospitalized so that they can receive fluids and nutrients. Some women feel better after their 20th week of pregnancy, while others experience the symptoms throughout their pregnancy.¹⁰
• Iron-deficiency anemia. Pregnant women need more iron than normal for the increased amount of blood they produce during pregnancy. Iron-deficiency anemia—when the body doesn't have enough iron—is somewhat common during pregnancy and is associated with preterm birth and low birth weight. Symptoms of a deficiency in iron include feeling tired or faint, experiencing shortness of breath, and becoming pale. ACOG recommends 27 milligrams of iron daily (found in most prenatal vitamins) to reduce the risk for iron-deficiency anemia. Some women may need extra iron through iron supplements.¹² Your health care provider may screen you for iron-deficiency anemia and, if you have it, may recommend iron supplements.¹³