Congenital Zika syndrome

What is congenital Zika syndrome?

Congenital Zika syndrome is a group of birth defects associated with Zika infection during pregnancy. Zika is a virus. If you get infected with Zika during pregnancy, the virus can pass through the placenta to your baby. The placenta grows in your uterus (womb) and supplies your baby with food and oxygen through the umbilical cord. Being infected with Zika before birth increases a baby’s risk for these conditions, but not all babies infected have these conditions.

About 1 in 10 pregnant women (10 percent) with Zika infection in the United States and the District of Columbia has a baby with birth defects. A birth defect is a health condition that is present at birth. Birth defects change the shape or function of one or more parts of the body. They can cause problems in overall health, in how the body develops or in how the body works. Pregnant women with Zika infection during the first trimester may be more likely to have a baby with birth defects than women infected later in pregnancy. In the United States, the birth defects most strongly linked to Zika infection during pregnancy (like microcephaly) have increased in Puerto Rico and south Florida and Texas where Zika has spread locally. Zika is still spreading in Puerto Rico. Spread of Zika is expected to be low in Florida and Texas, but some people may still get infected.

Being infected with Zika before birth increases a baby’s risk for birth defects, but not all babies infected have them. Researchers are trying to find out more about babies who are infected or who may have been infected with Zika before birth. This research helps us learn how Zika may affect a baby’s health and development at birth and later in life. This is why It’s important for these babies to get early regular medical care.

Congenital Zika syndrome includes these five birth defects:

1. Severe microcephaly with a partly collapsed skull. Microcephaly is a birth defect in which a baby’s head is smaller than expected, compared to babies of the same sex and age. Babies with mild microcephaly often don’t have problems other than small head size. A baby with severe microcephaly has a head that’s much smaller than expected and may have more serious health problems than a baby with mild microcephaly. A baby can develop microcephaly after birth if her head growth slows or doesn’t develop. We don’t know if a newborn who’s infected with Zika around the time of birth will develop microcephaly after birth.
2. Less brain tissue than normal, with a specific pattern of brain damage that includes calcium deposits in the deep tissues of the brain. This calcium can build up and affect the way a baby’s brain works.
3. Damage to the back of the eye, including macular scarring. The retina is the nerve tissue that lines the back of the eye. It senses light and sends images to your brain. The center of the retina is called the macula. The macula gives the sharp, central vision you need for reading, driving and seeing fine detail. Macular scarring happens when scar tissue forms on the macula.
4. Problems with limbs or joints, including birth defects like arthrogryposis, clubfoot and congenital hip dysplasia. A joint is a part of the body where two or more bones come together, like the knee, hip, elbow or shoulder. A baby with arthrogryposis is born with joint problems that make it hard for her to move her hands or legs. Her joints may not move the right way or they may get stuck in one position. If a baby has clubfoot, one foot or both feet point down and turn in. Babies with clubfoot also may have abnormal foot bones, ankle joints and muscles. Babies born with hip dysplasia have an abnormal hip joint where the top of a hip bone doesn't stay firmly in the hip socket.
5. Hypertonia that limits a baby’s movement after birth. Hypertonia is when your baby has too much muscle tone, so his hands or legs may be stiff and hard to move.

If the Zika virus reaches your baby’s brain, it can slow brain growth and kill brain cells, and some parts of the brain may not develop. Problems in the brain that are linked to congenital Zika virus infection include:

• Brain atrophy. This is a loss of brain cells that can make the brain shrink. Sometimes all of the brain shrinks; other times only a small part of the brain shrinks.
• Brain structures that are missing or don’t develop properly. For example, some babies that may have been exposed to Zika during pregnancy have hypoplasia of the cerebellum. The cerebellum is the part of your brain that helps control your balance and how your body moves. Hypoplasia of the cerebellum is when the cerebellum is smaller than usual or it’s not fully developed.
• Neural tube defects (also called NTDs). An NTD is a birth defect in a baby’s neural tube. The neural tube is part of a developing baby that becomes the brain and spine. Examples of NTDs are spina bifida and anencephaly.
• Fetal brain disruption sequence. Babies with this condition may have severe microcephaly, problems with the skull (including collapsed skull or skull bones that overlap), extra skin on the scalp and problems with the nervous system. Your baby’s nervous system is made up of the brain, spinal cord and nerves. The nervous system helps your baby move, think and feel.
• Smooth brain. A healthy brain has many folds and grooves in it. For some babies, the brain may be smooth with no folds or few folds. Some babies with smooth brain don’t have serious health problems, but others stop developing after 3 to 5 months and many die before they’re 2 years old.
• Thin cerebral cortex with enlarged ventricles and hydrocephalus. The cerebral cortex is the thin layer of cells that covers the brain. It helps the brain process information. Ventricles are spaces in the brain that fill with fluid. When fluid builds up, it causes pressure on the brain. This is called hydrocephalus.

Other health conditions linked to congenital Zika infection include:

• Cerebral Palsy. This is a group of conditions that affects the parts of the brain that control muscles. This can cause problems with movement, posture (standing up straight) and balance.
• Low birthweight. This is when a baby is born weighing less than 5 pounds, 8 ounces. 
• Growth and development problems, including trouble swallowing (also called dysphagia), problems with balance and movement, trouble sitting up and intellectual and developmental disabilities. These are problems with how the brain works that can cause a person to have trouble or delays in physical development, learning, communicating, taking care of himself or getting along with others.
• Hearing loss and other hearing problems. Hearing loss is when your baby can’t hear sound in one or both ears. 
• Nervous system problems, including epilepsy, hypotonia, hyperreflexia, severe fussiness and tremors (also called body shakes). Epilepsy is a seizure disorder that affects how the nerve cells in your brain work. A seizure is when the whole body or parts of the body move without control. Hypotonia is when your baby has too little muscle tone, so he may seem floppy and have poor head control (his head falls forward, backward or to the side). Hyperreflexia is when you baby has overactive reflexes.
• Sleeping problems
• Vision problems, including cataracts, coloboma and congenital glaucoma. A cataract is a film or cloud that covers the eye’s lens and affects a baby’s vision. Coloboma is when there are missing pieces of tissues in the structures that form the eye. Congenital glaucoma is a group of diseases that damage the eye’s optic nerve. The optic nerve connects the retina to the brain. Glaucoma can lead to vision loss and blindness.

How can you prevent congenital Zika syndrome in your baby?

You can prevent congenital Zika syndrome in your baby by not getting infected with Zika before or during pregnancy. The Zika virus is spread mostly through infected mosquitoes. You also can get it by having unprotected sex with an infected person or by coming into contact with infected body fluids, like through a blood transfusion or if you work in a health care setting. Learn how to protect yourself from Zika infection to prevent congenital Zika syndrome in your baby. 

How is congenital Zika syndrome diagnosed?

Not all babies are checked for congenital Zika syndrome after birth. Your baby should get tested for Zika infection and health conditions that are part of congenital Zika syndrome if:

• Your baby has birth defects that are part of congenital Zika syndrome and you may have been exposed to Zika during pregnancy.
• Your baby doesn’t have birth defects that are part of congenital Zika syndrome, but lab tests show you possibly had Zika infection during pregnancy.

If you may have been exposed to Zika during pregnancy, but lab tests don’t show possible Zika infection and your baby doesn’t have birth defects that are part of congenital Zika syndrome, talk to your baby’s provider to decide if testing is right for your baby. Even if your baby looks and seems healthy at birth, he may have effects of congenital Zika syndrome as he gets older. So it’s important that you take him to all his medical checkups so his providers can make sure he’s doing well. Checkups also let providers spot and treat conditions early to help prevent health problems later on. Tell your provider if you’re worried about your baby’s health and development.

Your baby’s health care provider uses these tests to check for Zika infection and related health conditions:

• A blood and urine test for Zika. Your baby gets tested as soon as possible, ideally within the first few days after birth. Your baby’s spinal fluid may be tested for Zika, especially if your baby’s blood and urine tests are negative for Zika and your baby’s provider can’t find another cause of your baby’s birth defects.
• A physical exam to check your baby’s head size, weight and length
• An eye exam before your baby’s 1 month old to check for vision problems
• A hearing test called automated auditory brainstem response (also called AABR). Your baby gets this test before she’s 1 month old, if she didn’t have AABR as part of newborn screening. AABR uses patches called electrodes and a computer to check how your baby’s nerves in the brain react to sounds. Your baby gets newborn screening before she leaves the hospital after birth. Newborn screening checks for serious but rare conditions that your baby has at birth. It includes blood, hearing and heart screening.
• Ultrasound of the head before your baby’s 1 month old to check her skull and brain. An ultrasound uses sound waves and a computer screen to show a picture of the inside of your baby's body.

If your baby was infected with Zika before birth, was born with congenital Zika syndrome or may have congenital Zika syndrome, does he need special medical care?

Yes. If your baby was infected before birth or has or may have congenital Zika syndrome, a team of health care providers cares for your baby. The kind of checkups and medical care your baby needs depend on his condition at birth.

The team of providers caring for your baby knows how to treat health conditions that come with congenital Zika syndrome. They work together to coordinate your baby’s care to make sure she gets regular medical checkups as she grows, as well as treatment she needs for conditions that come with congenital Zika syndrome. Depending on your baby’s condition, she may need long-term treatment.

Your baby’s health care team is led by the provider who gives your baby general medical care. This may be your baby’s regular health care provider, or it may be a provider who has more experience taking care of babies with congenital Zika syndrome. If your baby has congenital Zika syndrome, the lead provider may be a: 

• Pediatrician. This is a doctor who has training to take care of babies and children.
• Family practice doctor (also called a family physician). This is a doctor who takes care of every member of the family. A family practice doctor can be your health care provider before, during and after pregnancy, and your baby's provider, too.
• Neonatologist. This is a doctor who takes care of sick newborns, including preterm babies (babies born before 37 weeks of pregnancy) and babies with birth defects. 
• Pediatric nurse practitioner (also called PNP). This is a registered nurse who has advanced training to take care of babies and children. 
• Family nurse practitioner (also called FNP). This is a registered nurse with advanced training to take care of every member of your family. 

Providers who treat problems with digestion and feeding

• Gastroenterologist. This doctor treats digestion and feeding problems. Digestion is the process of how your baby’s body breaks down food after she eats. 
• Lactation consultant. This person is trained to help women breastfeed, even women who have breastfeeding problems. 
• Nutritionist. This person can help make sure your baby gets all the nutrients she needs for healthy growth and development. 
• Pulmonologist. This doctor treats lung conditions, like aspiration. Aspiration is when your baby sucks food or drink into her airway.
• Otolaryngologist (also called an ear, nose and throat specialist or ENT). This doctor may treat your baby if she has feeding problems, like poor suck, trouble swallowing, reflux or aspiration. Reflux is when the milk or food your baby swallows comes back up into her esophagus. The esophagus is the tube that carries food and drink from your baby’s mouth to her stomach. 

Providers who treat problems with the eyes and ears

• Audiologist. This provider has training to treat hearing problems and hearing loss.
• Ophthalmologist. This is a doctor who treats eye problems.
• ENT. This doctor treats problems of the ears, nose and throat.

Providers who treat problems with the brain, nerves, spine, bones and joints

• Endocrinologist. This doctor treats gland or hormone problems. A gland is an organ that makes hormones (chemicals) that help your baby’s body work. Babies with brain development problems may have problems with their glands and hormones. 
• Neurologist. This doctor treats brain, spine and nerve problems.
• Orthopedist. This doctor treats bone and joint problems. 
• Physiatrist. This doctor treats health conditions that affect the brain, nerves, bones and muscles. He also has special training in treating patients with disabilities. 
• Radiologist. This doctor uses imaging tests to diagnose and treat disease, like microcephaly and other problems. Imaging tests include ultrasound and magnetic resonance imaging (also called MRI). MRI is a medical test that makes a detailed picture of the inside of your baby. 

Providers who treat developmental conditions

• Developmental pediatrician. This doctor has training in child development and taking care of children with special needs. If your baby has developmental delays, he may need to see a developmental pediatrician. Developmental delays are when your child doesn’t reach developmental milestones when expected. Milestones are skills or activities that most children can do at a certain age. Milestones include sitting, walking, talking, having social skills and having thinking skills. 
• Occupational therapist. This person trained to help people learn to do everyday activities. For children, this may be things like brushing teeth, getting dressed, putting on shoes or learning to use a pencil. If your baby has feeding problems, she may need treatment from an occupational therapist.
• Physical therapist. This provider creates exercise programs to help build strength and help with movement. If your baby has a condition like hypertonia, clubfoot or arthrogryposis, physical therapy may help these conditions. 
• Speech therapist. This provider helps people with speech and language problems. A speech therapist also may help your baby if she has feeding problems.

Other providers who treat conditions caused by congenital Zika syndrome 

• Infectious disease specialist. This doctor diagnoses and treats infections. He checks your baby for infections that may cause problems for your baby, including syphilis, toxoplasmosis, rubella, cytomegalovirus and herpes.
• Clinical geneticist. This doctor tries to find out the causes of birth defects and other genetic conditions (health conditions caused by genes). If your baby has microcephaly, a clinical geneticist may check to see if it’s caused by something other than Zika infection. 

Providers who help families take care of a sick baby and cope with the stress of having a sick baby

• Mental health professional. This provider helps people with emotional or mental health problems, like depression. She can help people cope with the stress of caring for a baby with health conditions that come with congenital Zika syndrome. Mental health providers include social workers, therapists, counselors, psychologists, psychiatrists and psychiatric nurse practitioners.
• Social worker. A social worker help people solve problems and make their lives better. Most hospitals have social workers who can help connect you with the resources you need to care for your baby.

If your baby has developmental delays, does she need early intervention services?

Yes. If your baby has developmental delays, it’s important to get early intervention services as soon as possible. Developmental delays are when your child doesn’t reach developmental milestones when expected. A developmental milestone is a skill or activity that most children can do at a certain age. Milestones include sitting, walking, talking, having social skills and having thinking skills. Early intervention services can help improve your child’s development. They can help children from birth through 3 years old learn important skills. Services include therapy to help a child talk, walk, learn self-help skills and interact with others.

The CDC program Learn the signs. Act early. offers tools and information for parents who think their child may have developmental delays. You can find your state’s contact information for early intervention services. You don’t need a doctor’s referral or a medical diagnosis to ask for a free screening.

If your baby has congenital Zika syndrome, is it OK to breastfeed?

Yes. Breast milk is the best food for most babies for the first year of life. If your baby has problems swallowing or feeding, his provider may refer you to a lactation consultant for help. Even if your baby breastfeeds well after birth in the hospital, he may have feeding problems after you’re home. If you’re worried about your baby’s feeding, tell his provider.

More information

• American Academy of Pediatrics (AAP)
• Centers for Disease Control and Prevention (CDC)

See also: Zika virus and pregnancy, Microcephaly, Protect your baby from Zika

Last reviewed: January 30, 2018