This sheet is about exposure to the Zika virus in pregnancy and while breastfeeding. This information is based on available published literature. 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 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. A person who has Zika can also pass the infection to their fetus during pregnancy.

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. The symptoms of Zika can be treated, 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 fetus.

How can I protect my pregnancy from Zika virus?*

If you or your partner are pregnant or planning to become pregnant, it is recommended to prevent mosquito bites during and after travel by using insect repellent and other steps recommended by the Centers for Disease Control and Prevention (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 for DEET at https://mothertobaby.org/fact-sheets/deet-nn-ethyl-m-toluamide-pregnancy/.

If you are pregnant, avoid traveling to areas with active outbreaks of Zika virus. Carefully consider the risks before traveling to areas where Zika has been reported in the past (for information about specific countries and territories, see https://www.cdc.gov/zika/geo/index.html). If you do travel to an area where Zika has been reported in the past, prevent mosquito bites and prevent getting or passing the virus through sex (sexual transmission) during and after travel (see next paragraph for more information about preventing sexual transmission).

If your partner is pregnant and you travel to an area with an active outbreak of Zika virus, prevent mosquito bites and sexual transmission of the virus during and after travel. If you travel to an area where Zika has been reported in the past, prevent mosquito bites and sexual transmission during travel. You and your partner can consider continuing to prevent sexual transmission after your travel if you are concerned about risks of Zika. Preventing sexual transmission of Zika means using condoms or not having sex for at least 3 months (for biological males) or at least 2 months (for biological females). For more information about preventing sexual transmission, see https://www.cdc.gov/zika/prevention/index.html.

If you or your partner are planning a pregnancy and you travel to an area with an active outbreak of Zika virus, prevent mosquito bites and wait to get pregnant after traveling. If you travel to an area where Zika has been reported in the past, prevent mosquito bites and consider waiting to get pregnant if you are concerned about risks of Zika. The timeframe for waiting to get pregnant is at least 3 months (for biological males) or at least 2 months (for biological females).

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?

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 fetus. If this happens, the fetus 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, 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.

Does having Zika virus increase the chance of other pregnancy-related problems?

Zika infection in pregnancy can increase the chance of stillbirth, preterm delivery (birth before week 37), the fetus 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 issues, there is still a chance they can later have issues, such as delays in meeting developmental milestones, or epilepsy (seizure disorder).

Can I just be tested for Zika virus instead of waiting to get pregnant or using condoms?

Zika testing is not a good way to know if it is safe to get pregnant or if you could pass the virus to your partner through sex. There is no available test to know if there is Zika virus in a person’s semen. People with possible or known exposure to the virus should wait the recommended times before trying to get pregnant (2 months for females and 3 months for males), and people 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. Experts believe that the benefits of breastfeeding outweigh any potential risks of Zika virus infection through breastfeeding.

Some research suggests that children with congenital Zika syndrome (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 male has Zika virus, could it affect fertility 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. Lower sperm count can affect fertility (ability to get partner pregnant).

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 general information on paternal exposures, please see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

Selected References:

• Antoniou E, et al. 2023. Congenital Zika Syndrome and Disabilities of Feeding and Breastfeeding in Early Childhood: A Systematic Review. Viruses; 15(3):601. [PMC free article: PMC10052454] [PubMed: 36992310]
• Blackmon K, et al. 2020. Epilepsy surveillance in normocephalic children with and without prenatal Zika virus exposure. PLoS Negl Trop Dis; 14:e0008874. [PMC free article: PMC7728266] [PubMed: 33253174]
• Cavalcante TB, et al. 2022. Characteristics associated with drug resistant epilepsy in children up to 36 months old with Congenital Zika Syndrome. Seizure; 103:92-98. [PubMed: 36368189]
• Cardoso TF, et al. 2019. Congenital Zika infection: neurology can occur without microcephaly. Archives of Disease in Childhood 104:199-200. [PubMed: 29858269]
• Centeno-Tablante E, et al. 2021. Update on the transmission of Zika virus through breast milk and breastfeeding: a systematic review of the evidence. Viruses Jan 18;13(1):123. [PMC free article: PMC7830280] [PubMed: 33477428]
• Centers for Disease Control and Prevention. 2024. Zika Virus. Available at URL: https://www​.cdc.gov/zika/index.html.
• Christie, C. et al. 2023. Dengue, chikungunya and zika arbovirus infections in Caribbean children. Current Opinion in Pediatrics 35(2):p 155-165. [PMC free article: PMC10090388] [PubMed: 36801979]
• Delaney A, et al. 2018. Population-based surveillance of birth defects potentially related to Zika virus infection — 15 states and U.S. territories, 2016. MMWR Morb Mortal Wkly Rep 2018;67:91–96. [PMC free article: PMC5812309] [PubMed: 29370151]
• Díaz C, et al. 2023. Craniofacial and dental features in children aged 3-5 years with congenital Zika syndrome. Clin Oral Investig.;27(9):5181-5188. [PMC free article: PMC10492677] [PubMed: 37578656]
• Joguet G, et al. 2017. Effect of acute Zika virus infection on sperm and virus clearance in body fluids: a prospective observational study. Lancet Infect Dis 17(11):1200-1208. [PubMed: 28838639]
• Martins MM, et al. 2021.Fetal, neonatal, and infant outcomes associated with maternal Zika virus infection during pregnancy: a systematic review and meta-analysis. PLOS ONE 16(2): e0246643. [PMC free article: PMC7894820] [PubMed: 33606729]
• Mercado-Reyes M, et al. 2021. Pregnancy, birth, infant, and early childhood neurodevelopmental outcomes among a cohort of women with symptoms of Zika virus disease during pregnancy in three surveillance sites, Project Vigilancia de Embarazadas con Zika (VEZ), Colombia, 2016-2018. Trop Med Infect. Dis 6(4),183. [PMC free article: PMC8544689] [PubMed: 34698287]
• Polen KD, et al. 2018. Update: interim guidance for preconception counseling and prevention of sexual transmission of Zika virus for men with possible Zika virus exposure - United States, August 2018. MMWR Morb Mortal Wkly Rep. 2018 Aug 10;67(31):868-871. [PMC free article: PMC6089331] [PubMed: 30091965]
• Rasmussen SA, et al. 2016. Zika virus and birth defects - reviewing the evidence for causality. N Engl J Med 374:1981-1987. [PubMed: 27074377]
• Rice ME, et al. 2018. Vital signs: Zika-associated birth defects and neurodevelopmental abnormalities possibly associated with congenital Zika virus infection — U.S. territories and freely associated states, 2018. MMWR Morb Mortal Wkly Rep 2018;67:858-867. [PMC free article: PMC6089332] [PubMed: 30091967]
• Rua EC, et al. 2022. Two-year follow-up of children with congenital Zika syndrome: the evolution of clinical patterns. Eur J Pediatr; 181(3):991-999. [PubMed: 34661750]
• Shapiro-Mendoza CK, et al. 2017. Pregnancy Outcomes After Maternal Zika Virus Infection During Pregnancy — U.S. Territories, January 1, 2016-April 25, 2017. MMWR Morb Mortal Wkly Rep 2017;66:615-621. [PMC free article: PMC5657842] [PubMed: 28617773]
• Smoots AN, et al. 2020. Population-based surveillance for birth defects potentially related to Zika virus infection — 22 states and territories, January 2016-June 2017. MMWR Morb Mortal Wkly Rep 2020;69:67–71. [PMC free article: PMC7367037] [PubMed: 31971935]
• Valdes V, et al. 2019. Cognitive development of infants exposed to the Zika Virus in Puerto Rico. JAMA Netw Open; 2:e1914061. [PMC free article: PMC6822087] [PubMed: 31651970]
• World Health Organization. 2016. Infant feeding in areas of Zika virus transmission. Available at URL: https://reliefweb​.int/sites/reliefweb​.int​/files/resources/WHO_ZIKV_MOC_16​%205_eng.pdf. [PubMed: 27441334]

“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.