This sheet is about having Zika virus in pregnancy or while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare provider.
What is Zika? How do people get it?
Zika is a virus that is usually spread by infected mosquitoes. Not all mosquitoes carry the Zika virus, and not every person bitten by an infected mosquito will get Zika. Other ways people can get Zika include sexual contact with an infected partner (vaginal, anal, or oral sex, or sharing of sex toys), and through contact with infected blood (from transfusions, needle sticks, or sharing needles with an infected person). During pregnancy, Zika can pass from the pregnant woman to the fetus. When this happens, there is an increased chance of serious birth defects and developmental problems.
Four out of 5 people (80%) who have Zika virus do not have symptoms. Those who do have symptoms usually have a mild flu-like illness with fever, rash, headache, joint and/or muscle pain, and conjunctivitis (“pink eye”). Symptoms can begin 3-7 days after being infected and can last for several days to a week. There is no cure or vaccine for Zika. The symptoms of Zika can be treated, but treatment does not prevent the virus from spreading. Even if an infected person has no symptoms, they can still pass the virus to others through sex or to a fetus during pregnancy.
Can I be tested for Zika?
People who have Zika symptoms and have traveled to an area with current or past Zika virus transmission or had sex with someone who recently traveled to one of these areas, should be tested. Testing is not routinely recommended if you are pregnant and do not have Zika symptoms but can be considered after talking to your healthcare provider. The Centers for Disease Control and Prevention (CDC) has more information about testing here: https://www.cdc.gov/zika/testing/index.html.
How can I protect myself from Zika virus during travel?
Prevent mosquito bites during and after travel by using insect repellent and taking other steps recommended by the CDC at https://www.cdc.gov/mosquitoes/prevention/preventing-mosquito-bites-while-traveling.html. MotherToBaby has fact sheets for Insect Repellents at https://mothertobaby.org/fact-sheets/insect-repellents/ and DEET at https://mothertobaby.org/fact-sheets/deet-nn-ethyl-m-toluamide-pregnancy/.
Depending on where you travel, it might be recommended to take steps to prevent sexual transmission of Zika (getting or passing the virus through sex) and/or delaying pregnancy after travel. To prevent sexual transmission of Zika, use condoms or dental dams, do not share sex toys, and do not have sex during travel and for a period after travel (2 months for females or 3 months for males). Follow these same timeframes (2 months for females and 3 months for males) if you want to wait to get pregnant until a potential Zika virus infection has cleared from the body. See below for specific recommendations based on Zika risk at your destination(s).
Check for Zika risk at your destination(s). Before traveling, look at the CDC website for any active Zika Travel Health Notices at: https://wwwnc.cdc.gov/travel/notices.
- If you are pregnant, avoid traveling to areas with active Zika Travel Health Notices. If you must travel, prevent mosquito bites and sexual transmission of Zika virus during and after travel according to the CDC guidelines.
- If your female partner is pregnant and you choose to travel to an area with an active Zika Travel Health Notice, prevent mosquito bites and sexual transmission during and after travel according to the CDC guidelines.
- If you are planning a pregnancy and you travel to an area with an active Zika Travel Health Notice, prevent mosquito bites, prevent sexual transmission, and delay pregnancy according to the CDC guidelines.
Some areas still have low levels of Zika virus transmission even if there is no active Zika Travel Health Notice. For information about Zika risk in specific countries and territories, see https://www.cdc.gov/zika/geo/index.html. It is hard to know the exact level of transmission in many areas. Carefully consider the risks of Zika before traveling to areas with current or past transmission of Zika virus.
- If you or your female partner are pregnant and you travel to an area with current or past transmission, prevent mosquito bites during and after travel. If you are concerned about the risks of Zika, prevent sexual transmission during and after travel according to the CDC guidelines.
- If you or your female partner are planning a pregnancy and you travel to an area with current or past transmission, prevent mosquito bites during and after travel. If you are concerned about the risks of Zika, prevent sexual transmission during and after travel, and consider delaying pregnancy according to the CDC guidelines.
Does having Zika virus increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Zika infection in pregnancy can increase the chance of miscarriage.
Does having Zika virus in pregnancy increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like Zika, might increase the chance of birth defects in a pregnancy.
When a pregnant woman is infected with Zika, the virus can sometimes pass to the fetus. If this happens, there is an increased chance for a range of serious birth defects and developmental problems in the baby. The most severe outcome of Zika exposure in pregnancy is congenital Zika syndrome (CZS). Babies with CZS can have severe microcephaly (very small head size), serious brain changes (including a thinner outer layer of the brain, and calcium deposits in the brain where damage has occurred), eye defects (including scarring and vision problems), contractures (tightening that reduces movement) of the joints, and very stiff muscles. Other possible outcomes include feeding difficulties (such as trouble swallowing), hydrocephalus (a buildup of fluid in the brain), seizures, and hearing loss.
Some babies may only have some CZS features. Other babies may be born with no apparent effects from Zika infection but can later have slower head and brain growth (postnatal microcephaly). Research has also shown that even when a baby does not have noticeable Zika-associated issues at birth, there is still a chance they can have issues later on, such as seizures or delays in meeting developmental milestones (for more details see the question: “Does having Zika virus in pregnancy affect future behavior or learning for the child?” below).
The chance for a baby to experience CZS or other complications from Zika virus seems to be highest when the infection happens late in the first trimester or in the second trimester. However, Zika infection at any point in pregnancy can lead to serious problems in the baby. There is no safe time to get infected with Zika virus during pregnancy.
Does having Zika virus increase the chance of other pregnancy related problems?
Zika infection in pregnancy can increase the chance of preterm delivery (birth before week 37), low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth), small for gestational age (the fetus being smaller than expected for the timing in pregnancy), and stillbirth. Children with CZS have an increased chance of death due to complications from the syndrome.
Does having Zika virus in pregnancy affect future behavior or learning for the child?
Children with CZS have an increased chance of learning issues due to the serious effects the virus can have on the brain. Language delays, motor delays (crawling or walking on time), and trouble reaching other developmental milestones can occur. Babies infected with Zika during pregnancy may have more trouble with thinking, learning, and remembering.
What screenings or tests are available to see if my pregnancy has birth defects or other issues?
Prenatal ultrasounds can be used to screen for some birth defects, such as microcephaly. Ultrasound can also be used to monitor the growth of the pregnancy. Talk with your healthcare provider about any prenatal screenings or testing that are available to you. There are no tests available during pregnancy that can tell how much effect there could be on future behavior or learning.
Breastfeeding while I have Zika virus:
Zika virus has been found in breast milk. Although a few cases of Zika have been reported in breastfed infants of women who were infected with Zika virus, it is not clear if the infants got the virus from the breast milk. In most cases, the virus is not expected to pass to the baby from the milk. Experts believe that the benefits of breastfeeding outweigh any potential risks of Zika virus infection through breastfeeding.
Children with CZS can have trouble with feeding, such as issues with swallowing or suckling. If you are concerned about your baby’s feeding habits or weight gain, talk with your baby’s pediatrician. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man has Zika virus, can it affect his fertility or increase the chance of birth defects?
One study showed that having a Zika infection lowered sperm count (number of sperm produced), which could temporarily affect men’s fertility (ability to get a woman pregnant). Sperm count returned to normal within several months after the infection cleared.
If a man has Zika, he can pass the virus to his partner through unprotected sex. This can increase the chance of birth defects in a woman’s pregnancy. Men who might have been exposed to Zika virus should take steps to avoid passing the virus to a partner through sex, even if they do not have symptoms (for more information, see https://www.cdc.gov/zika/prevention/index.html). For more general information on paternal exposures, please see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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