This sheet is about exposure to the Zika virus in pregnancy and while breastfeeding. This information 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), from an infected person to their fetus during pregnancy, and through blood to blood contact with infected blood (from transfusions, needle sticks, or sharing needles with an infected person). Blood donations in the United States are screened for Zika virus.
Four out of 5 people 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. A person with Zika can treat the symptoms, but there is no cure or vaccine for Zika. Even if an infected person treats their symptoms, or even if they do not have symptoms, they can still pass the virus to others through sex or to a developing baby in pregnancy.
How can I protect my pregnancy from Zika virus?
If you are not pregnant yet, it is recommended to wait before trying to get pregnant after a known or possible exposure to Zika virus. Women should wait at least 2 months and men should wait at least 3 months, even if they do not have symptoms. During these wait times, everyone should use barrier methods (like condoms) and effective birth control to prevent pregnancy and protect their sexual partners from the virus. See https://www.cdc.gov/zika/pregnancy/women-and-their-partners.html for more details.
If you are pregnant, avoid traveling to areas where there are known outbreaks of Zika (red areas on the Centers for Disease Control and Prevention [CDC] Zika map), and carefully consider the risks of Zika before traveling to areas where there may be a chance of infection (purple areas on the map): https://wwwnc.cdc.gov/travel/page/zika-travel-information. If you travel to an area with a chance of Zika, help prevent mosquito bites by using insect repellent and taking other precautions recommended by the CDC at https://www.cdc.gov/zika/prevention/prevent-mosquito-bites.html. MotherToBaby has fact sheets for Insect Repellents at https://mothertobaby.org/fact-sheets/insect-repellents/ and for DEET at https://mothertobaby.org/fact-sheets/deet-nn-ethyl-m-toluamide-pregnancy/.
If you are pregnant, avoid having sex with a partner who might have the virus, or use a barrier method like a condom every time for vaginal, anal, or oral sex, for the rest of the pregnancy. See https://www.cdc.gov/pregnancy/zika/protect-yourself.html for more details.
Does having Zika virus increase the chance for miscarriage?
Miscarriage can occur in any pregnancy. Zika infection in pregnancy can increase the chance of miscarriage.
Does having Zika virus in pregnancy increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. When a person who is pregnant gets Zika, the virus can pass to the developing baby. If this happens, the baby has an increased chance of certain birth defects and developmental problems known as congenital Zika syndrome (CZS). CZS can include microcephaly (very small head and brain), severe brain defects, eye defects, hearing loss, seizures, and/or problems with the development and movement of the joints and limbs.
Studies suggest that about 5-10% of babies born to people with confirmed Zika infection during pregnancy will have birth defects related to the infection. The chance is highest with a Zika infection in the first trimester, but birth defects related to Zika can also happen after infection in the second or third trimester.
Would having Zika virus increase the chance of other pregnancy related problems?
In addition to birth defects and other problems related to CZS, a Zika infection in pregnancy can increase the chance of stillbirth, preterm delivery (birth before week 37), and effects on the baby’s growth, including being smaller than expected for the timing in pregnancy (small for gestational age) and having low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
Does having Zika virus in pregnancy affect future behavior or learning for the child?
Sometimes a baby can be born with no apparent effects from Zika infection, but can later have slowed head and brain growth (called postnatal microcephaly). Research has also shown that even when a baby does not have noticeable Zika-associated birth defects or postnatal microcephaly, there is still a chance they can later have problems related to brain damage, including delays meeting their developmental milestones. As they grow older, children affected by Zika will need ongoing specialized care from many types of healthcare providers and caregivers.
Can I just be tested for Zika virus instead of waiting to get pregnant or using condoms?
Zika tests are not a good way to know if the virus is transmissible. You can still pass the virus to your partner during sex and can increase risks if you become pregnant. At this time there is no way to test the semen for Zika virus. People with possible or known exposure to the virus should wait the recommended times before trying to get pregnant (2 months for women and 3 months for men), and men with pregnant sex partners should use condoms for the rest of the pregnancy, even if they receive a negative Zika blood test result.
Breastfeeding and Zika virus:
Zika virus has been found in breast milk, but there have not been any reported cases of infants getting Zika through breastfeeding. Based on current information, experts believe that the benefits of breastfeeding outweigh any potential risks of Zika virus infection through breastfeeding. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a male has Zika virus, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
A study showed that having a Zika infection lowered sperm count (number of sperms produced), but sperm count returned to normal within several months after infection. More research is needed to know about any long-term effects of a Zika infection on a man’s fertility.
If a male has Zika he can pass the virus to his partner through unprotected sex. This can increase the chance of birth defects in his partner’s pregnancy. Males who might have been exposed to Zika virus should use condoms and wait at least 3 months before trying to conceive a pregnancy, even if they do not have symptoms.
For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.
