The Hidden Realm

No relationship can be closer than that of a mother and her unborn child—yet the miraculous process taking place inside of you may seem as much of a mystery to you as to anyone else. A grainy black-and-white ultrasound image can be inspiring and reassuring, but it doesn’t show you very much about your baby.

What does this developing life really look like at 6 days after conception, at 6 weeks, at 6 months? How do intricately complex organs like the eyes form? When does your baby first suck his or her thumb—inside the womb? What does the embryonic heart look like when it starts beating, only about 21 days after conception? How much does your baby’s brain grow in the space of a month?

The moment a sperm penetrates the egg, chemical messengers relay news of the event to the brain, and the mother’s body immediately prepares for the new life. Tubal muscle movements and tiny hairlike projections called cilia transport the fertilized egg through the tube and into the uterus. The microscopic fertilized egg bores into the lush lining of womb, secures its site, and commences to grow with a vengeance.

Early Days

Whether they will become flatworms, lizards, or humans, embryos all develop in much the same way. The human embryo at about a month, when it is no bigger than a grain of rice, appears to be a tiny reptile, complete with tail.

Changes take place with amazing rapidity. About 21 days after conception the tiny, rudimentary heart begins to beat. At around 2 months, the embryo begins to acquire a clearly human aspect. The tail shrinks and toes and fingers become distinct. Inside the embryo, nerves feather themselves throughout the body and sex organs start to develop.

The months of pregnancy progress and the beauty and logic of the unfolding of life become clear. As though in a long, slow dance, eyes travel toward the front of the face while ears gradually climb up the head. Buds become limbs, toes and fingers emerge, facial features form—the fetus kicks, sucks his thumb, smiles.

After 9 months, this portion of your baby’s fantastic journey is complete. Everything lies in readiness for life outside of your protective womb—and the next stage of the journey.

Welcome to Your Baby’s World

The fertilized egg, termed a zygote, divides into 2 cells after about 24 hours, 4 cells after 48 hours, and 6-12 cells in 3 days. At about 5 days, the zygote has transformed into a hollow ball called the blastocyst.

The heart develops by folding in upon itself like a piece of origami. The early heart is not much more than two simple tubes that have fused together, twisted, and looped back on themselves. By week 5, the twisted tube fuses and becomes a two-chambered heart with one atrium and one ventricle. By week 6, a vertical wall known as the septum grows up into the middle of the two chambers.

By the time the baby is born, the brain will contain about 100 billion neurons—almost all the neurons it will ever have. The ear begins its development in the neck area and migrates up to the side of the head.

The embryo floats in an interior ocean—the amniotic fluid—contained by a membrane called the amnion. Salt is dissolved in the amniotic fluid in the same proportions as it is in our blood, tears, and the Earth’s oceans.

A woman's body undergoes enormous changes during pregnancy. The heart and kidneys must work harder because blood volume is higher. Cardiac output increases 30-50%. Heart rate increases to 80-90 beats per minute. The enlarged uterus, which reaches the lower edge of the rib cage by 36 weeks, compresses the bladder and intestines. This makes it necessary to urinate frequently, and it may also cause constipation. The mother’s spine curves more to balance the weight of the growing uterus.

Pregnancy is the term used to describe the period in which a fetus develops inside a woman's womb or uterus.

Pregnancy usually lasts about 40 weeks, or just over 9 months, as measured from the last menstrual period to delivery. Health care providers refer to three segments of pregnancy, called trimesters.

The events that lead to pregnancy begin with conception, in which a sperm penetrates an egg. The fertilized egg (called a zygote) then travels through the woman's fallopian tube to the uterus, where it implants itself in the uterine wall. The zygote is made up of a cluster of cells that later form the fetus and the placenta. The placenta connects the mother to the fetus and provides nutrients and oxygen to the fetus.

• Between 18 and 20 weeks, the typical timing for ultrasound to look for birth defects, you can often find out the sex of your baby.
• At 20 weeks, a woman may begin to feel movement.
• At 24 weeks, footprints and fingerprints have formed and the fetus sleeps and wakes regularly.
• According to research from the NICHD Neonatal Research Network, the survival rate for babies born at 28 weeks was 92%, although those born at this time will likely still experience serious health complications, including respiratory and neurologic problems.

• At 32 weeks, the bones are soft and yet almost fully formed, and the eyes can open and close.
• Infants born before 37 weeks are considered preterm. These children are at increased risk for problems such as developmental delays, vision and hearing problems, and cerebral palsy. Infants born between 34 and 36 weeks of pregnancy are considered to be "late preterm."
• Infants born in the 37th and 38th weeks of pregnancy—previously considered term—are now considered "early term." These infants face more health risks than infants who are born at 39 weeks or later, which is now considered full term.
• Infants born at 39 or 40 weeks of pregnancy are considered full term. Full-term infants have better health outcomes than do infants born earlier or, in some cases, later than this period. Therefore, if there is no medical reason to deliver earlier, it is best to deliver at or after 39 weeks to give the infant's lungs, brain, and liver time to fully develop.
• Infants born at 41 weeks through 41 weeks and 6 days are considered late term.
• Infants who are born at 42 weeks and beyond are considered post term.

Pregnancy lasts about 40 weeks, counting from the first day of your last normal period. The weeks are grouped into three trimesters. Find out what's happening with you and your baby in these three stages.

First trimester (week 1 – week 12)

During the first trimester your body undergoes many changes. Hormonal changes affect almost every organ system in your body. These changes can trigger symptoms even in the very first weeks of pregnancy. Your period stopping is a clear sign that you are pregnant. Other changes may include:

• Extreme tiredness
• Tender, swollen breasts. Your nipples might also stick out.
• Upset stomach with or without throwing up (morning sickness)
• Cravings or distaste for certain foods
• Mood swings
• Constipation (trouble having bowel movements)
• Need to pass urine more often
• Headache
• Heartburn
• Weight gain or loss

As your body changes, you might need to make changes to your daily routine, such as going to bed earlier or eating frequent, small meals. Fortunately, most of these discomforts will go away as your pregnancy progresses. And some women might not feel any discomfort at all! If you have been pregnant before, you might feel differently this time around. Just as each woman is different, so is each pregnancy.

Second trimester (week 13 – week 28)

Most women find the second trimester of pregnancy easier than the first. But it is just as important to stay informed about your pregnancy during these months.

You might notice that symptoms like nausea and fatigue are going away. But other new, more noticeable changes to your body are now happening. Your abdomen will expand as the baby continues to grow. And before this trimester is over, you will feel your baby beginning to move!

As your body changes to make room for your growing baby, you may have:

• Body aches, such as back, abdomen, groin, or thigh pain
• Stretch marks on your abdomen, breasts, thighs, or buttocks
• Darkening of the skin around your nipples
• A line on the skin running from belly button to pubic hairline
• Patches of darker skin, usually over the cheeks, forehead, nose, or upper lip. Patches often match on both sides of the face. This is sometimes called the mask of pregnancy.
• Numb or tingling hands, called carpal tunnel syndrome
• Itching on the abdomen, palms, and soles of the feet. (Call your doctor if you have nausea, loss of appetite, vomiting, jaundice or fatigue combined with itching. These can be signs of a serious liver problem.)
• Swelling of the ankles, fingers, and face. (If you notice any sudden or extreme swelling or if you gain a lot of weight really quickly, call your doctor right away. This could be a sign of preeclampsia.)

Third trimester (week 29 – week 40)

You're in the home stretch! Some of the same discomforts you had in your second trimester will continue. Plus, many women find breathing difficult and notice they have to go to the bathroom even more often. This is because the baby is getting bigger and it is putting more pressure on your organs. Don't worry, your baby is fine and these problems will lessen once you give birth.

Some new body changes you might notice in the third trimester include:

• Shortness of breath
• Heartburn
• Swelling of the ankles, fingers, and face. (If you notice any sudden or extreme swelling or if you gain a lot of weight really quickly, call your doctor right away. This could be a sign of preeclampsia.)
• Hemorrhoids
• Tender breasts, which may leak a watery pre-milk called colostrum (kuh-LOSS-struhm)
• Your belly button may stick out
• Trouble sleeping
• The baby "dropping", or moving lower in your abdomen
• Contractions, which can be a sign of real or false labor

As you near your due date, your cervix becomes thinner and softer (called effacing). This is a normal, natural process that helps the birth canal (vagina) to open during the birthing process. Your doctor will check your progress with a vaginal exam as you near your due date. Get excited — the final countdown has begun!

Your developing baby

First trimester (week 1 - week 12)

Second trimester (week 13 - week 28)

Third trimester (week 29-week 40)

If you have missed one or more menstrual periods or have one or more of the early signs of pregnancy, you may wonder whether you are pregnant.

Home pregnancy tests, which are highly accurate and available without a prescription, can be the first way women determine if they are pregnant. If a home pregnancy test is positive, a woman should call her health care provider to schedule an appointment.

Home pregnancy tests measure the amount of human chorionic gonadotropin (hCG) in a woman's urine. Small amounts of this hormone are present even before the first missed period, and they increase as pregnancy continues.

NICHD research in the 1970s led to the development of the home pregnancy test. Researchers were studying the role of hCG in tracking the success of a cancer treatment. During this study, researchers discovered that high levels of hCG in the urine were associated with pregnancy. Manufacturers used this research to create home pregnancy tests that detect hCG levels in urine with up to 97% accuracy.

The primary sign of pregnancy is missing a menstrual period or two or more consecutive periods, but many women experience other symptoms of pregnancy before they miss a period.

Missing a period does not always mean a woman is pregnant. Menstrual irregularities are common and can have a variety of causes, including taking birth control pills, conditions such as diabetes and polycystic ovary syndrome, eating disorders, and certain medications. Women who miss a period should see their health care provider to find out whether they are pregnant or whether they have another health problem.

Pregnancy symptoms vary from woman to woman. A woman may experience every common symptom, just a few, or none at all. Some signs of early pregnancy include:

• Slight bleeding. One study shows as many as 25% of pregnant women experience slight bleeding or spotting that is lighter in color than normal menstrual blood. This typically occurs at the time of implantation of the fertilized egg (about 6 to 12 days after conception) but is common in the first 12 weeks of pregnancy.
• Tender, swollen breasts or nipples. Women may notice this symptom as early as 1 to 2 weeks after conception. Hormonal changes can make the breasts sore or even tingly. The breasts feel fuller or heavier as well.
• Fatigue. Many women feel more tired early in pregnancy because their bodies are producing more of a hormone called progesterone, which helps maintain the pregnancy and encourages the growth of milk-producing glands in the breasts. In addition, during pregnancy the body pumps more blood to carry nutrients to the fetus. Pregnant women may notice fatigue as early as 1 week after conception.
• Headaches. The sudden rise of hormones may trigger headaches early in pregnancy.
• Nausea and/or vomiting. This symptom can start anywhere from 2 to 8 weeks after conception and can continue throughout pregnancy. Commonly referred to as "morning sickness," it can actually occur at any time during the day.
• Food cravings or aversions. Sudden cravings or developing a dislike of favorite foods are both common throughout pregnancy. A food craving or aversion can last the entire pregnancy or vary throughout this period.
• Mood swings. Hormonal changes during pregnancy often cause sharp mood swings. These can occur as early as a few weeks after conception.
• Frequent urination. The need to empty the bladder more often is common throughout pregnancy. In the first few weeks of pregnancy, the body produces a hormone called human chorionic gonadotropin, which increases blood flow to the pelvic region, causing women to have to urinate more often.

Many of these symptoms can also be signs of other conditions, the result of changing birth control pills, or effects of stress, so they do not always mean that a woman is pregnant. Women should see their health care provider if they suspect they are pregnant.

Having a healthy pregnancy is one of the best ways to promote a healthy birth. Getting early and regular prenatal care improves the chances of a healthy pregnancy. This care can begin even before pregnancy with a pre-pregnancy care visit to a health care provider.

Pre-Pregnancy Care

A pre-pregnancy care visit can help women take steps toward a healthy pregnancy before they even get pregnant.
Women can help to promote a healthy pregnancy and birth of a healthy baby by taking the following steps before they become pregnant:

• Develop a plan for their reproductive life.
• Increase their daily intake of folic acid (one of the B vitamins) to at least 400 micrograms.
• Make sure their immunizations are up to date.
• Control diabetes and other medical conditions.
• Avoid smoking, drinking alcohol, and using drugs.
• Attain a healthy weight.
• Learn about their family health history and that of their partner.
• Seek help for depression, anxiety, or other mental health issues.

Prenatal Care

Women who suspect they may be pregnant should schedule a visit to their health care provider to begin prenatal care. Prenatal visits to a health care provider usually include a physical exam, weight checks, and providing a urine sample. Depending on the stage of the pregnancy, health care providers may also do blood tests and imaging tests, such as ultrasound exams. These visits also include discussions about the mother's health, the fetus's health, and any questions about the pregnancy.

Pre-Pregnancy and prenatal care can help prevent complications and inform women about important steps they can take to protect their infant and ensure a healthy pregnancy. With regular prenatal care women can:

• Reduce the risk of pregnancy complications. Following a healthy, safe diet; getting regular exercise as advised by a health care provider; and avoiding exposure to potentially harmful substances such as lead and radiation can help reduce the risk for problems during pregnancy and promote fetal health and development. Controlling existing conditions, such as high blood pressure and diabetes, is important to prevent serious complications and their effects.

• Reduce the fetus's and infant's risk for complications. Tobacco smoke and alcohol use during pregnancy have been shown to increase the risk for Sudden Infant Death Syndrome. Alcohol use also increases the risk for fetal alcohol spectrum disorders, which can cause a variety of problems such as abnormal facial features, having a small head, poor coordination, poor memory, intellectual disability, and problems with the heart, kidneys, or bones. According to one recent study supported by the NIH, these and other long-term problems can occur even with low levels of prenatal alcohol exposure.
  
  In addition, taking 400 micrograms of folic acid daily reduces the risk for neural tube defects by 70%. Most prenatal vitamins contain the recommended 400 micrograms of folic acid as well as other vitamins that pregnant women and their developing fetus need. Folic acid has been added to foods like cereals, breads, pasta, and other grain-based foods. Although a related form (called folate) is present in orange juice and leafy, green vegetables (such as kale and spinach), folate is not absorbed as well as folic acid.

• Help ensure the medications women take are safe. Women should not take certain medications, including some acne treatments and dietary and herbal supplements, during pregnancy because they can harm the fetus.

​​"Full Term" Has a New Meaning

The meaning of "term" pregnancy has changed. "Term" has been replaced by more specific definitions that communicate the importance of the last few weeks of pregnancy for infant development. Learn why the term pregnancy definitions are important to promoting the best outcomes for mom and baby.

"Full Term" Starts at 39 Weeks

The American College of Obstetricians and Gynecologists and the Society for Maternal Fetal Medicine announced more specific definitions to describe babies born between 37 weeks and 42 weeks of pregnancy.

In the past, a baby born anytime between 37 weeks and 42 weeks was considered "term." A pregnancy is now considered "full term" at 39 weeks.

Why does this matter?

Research shows that babies do best when they are born during weeks 39 and 40.

Babies born before 39 weeks are at risk for problems with breathing, feeding, and controlling their temperature. They are also more likely to spend time in the neonatal intensive care unit, develop infections, and have a learning disability.

What does this mean for my pregnancy?

Waiting to deliver until at least 39 weeks, in a healthy pregnancy, gives your baby the time he or she needs to grow. Your baby's lungs, liver, and brain go through a crucial period of growth between 37 weeks and 39 weeks of pregnancy. Waiting until 39 weeks, now called "full term," gives your baby the best possible chance for a healthy start in life.

There may be a time, if there is a health risk to the mother or baby, when a planned delivery before 39 weeks is necessary. But in a healthy pregnancy, it's best to wait until at least 39 weeks.

It is important to know these terms so you and your health care provider can talk about what is best for the health of you and your baby.

A high-risk pregnancy is one that threatens the health or life of the mother or her fetus. It often requires specialized care from specially trained providers.

Some pregnancies become high risk as they progress, while some women are at increased risk for complications even before they get pregnant for a variety of reasons.

Early and regular prenatal care helps many women have healthy pregnancies and deliveries without complications.

Risk factors for a high-risk pregnancy can include:

• Existing health conditions, such as high blood pressure, diabetes, or being HIV-positive
• Overweight and obesity. Obesity increases the risk for high blood pressure, preeclampsia, gestational diabetes, stillbirth, neural tube defects, and cesarean delivery. NICHD researchers have found that obesity can raise infants' risk of heart problems at birth by 15%.
• Multiple births. The risk of complications is higher in women carrying more than one fetus (twins and higher-order multiples). Common complications include preeclampsia, premature labor, and preterm birth. More than one-half of all twins and as many as 93% of triplets are born at less than 37 weeks' gestation.
• Young or old maternal age. Pregnancy in teens and women age 35 or older increases the risk for preeclampsia and gestational high blood pressure.

Women with high-risk pregnancies should receive care from a special team of health care providers to ensure the best possible outcomes.

Some women experience health problems during pregnancy. These complications can involve the mother's health, the fetus's health, or both. Even women who were healthy before getting pregnant can experience complications. These complications may make the pregnancy a high-risk pregnancy.

Getting early and regular prenatal care can help decrease the risk for problems by enabling health care providers to diagnose, treat, or manage conditions before they become serious. Prenatal care can also help identify mental health concerns related to pregnancy, such as anxiety and depression.

Some common complications of pregnancy include, but are not limited to, the following.

High Blood Pressure

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. Reduced blood flow can slow the growth of the fetus and place the mother at greater risk of preterm labor and preeclampsia.

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

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.

Infections

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. 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:

• 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
• Birth defects, 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. 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.

Preeclampsia

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:

• First pregnancies
• Preeclampsia in a previous pregnancy
• Existing conditions such as high blood pressure, diabetes, kidney disease, and systemic lupus erythematosus
• Being 35 years of age or older
• Carrying two or more fetuses
• Obesity

Preterm Labor

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.

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.

Depression & Anxiety

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. 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.

Pregnancy Loss/Miscarriage

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. Women experiencing this sign at any point in their pregnancy should contact their health care provider.

Stillbirth

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.

Other Complications

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.
  
  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.
• 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. Your health care provider may screen you for iron-deficiency anemia and, if you have it, may recommend iron supplements.

Infections that can affect the health of the pregnant woman, the pregnancy, and the baby after delivery include (but are not limited to):

• Bacterial vaginosis (pronounced vaj-in-NOH-sis) 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.
• 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. 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.
• Cytomegalovirus (CMV) (pronounced sahy-toh-meg-uh-loh-VAHY-ruhs) 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.
• Fifth disease is caused by human parvovirus (pronounced PAHR-voh-vahy-ruhs) 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 pregnant women or the fetus, but in rare cases, the woman might have 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 women to see if they are immune to the virus already.
• 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 women reduces the risk of transmission.
• 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. Learn more about GBS and pregnancy.
• 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 a woman has active herpes sores when she goes into labor, the infant can be delivered by cesarean section to reduce the chance that the infant will come in contact with the virus.
• 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. For more information about Hep B during pregnancy, visit the Centers for Disease Control and Prevention (CDC) website. 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). CDC offers more information about HCV.
• HIV/AIDS. HIV can be passed from mother to infant during pregnancy before birth, at the time of delivery, or after birth during breastfeeding.
• Human papillomavirus (HPV). CDC offers more information about HPV, including vaccine recommendations.
• Listeria or listeriosis (pronounced li-steer-ee-OH-sis) 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.
• 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 women get vaccinated against rubella before they get pregnant. Learn more about rubella and pregnancy.
• Syphilis may pass from an infected mother to her 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 women should be screened for syphilis during their first prenatal visit. Women considered to be high risk should be screened again in the third trimester.
• Toxoplasmosis (pronounced tok-soh-plaz-MOH-sis) 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 woman to the developing fetus, it can cause intellectual disabilities, blindness, or other problems. Women 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.
• Trichomoniasis. CDC offers more information about trichomoniasis.
• 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.