Updated: March 25, 2016

How does Zika virus affect pregnant women and fetuses?

Pregnant women have the same risk as the rest of the population of being infected with Zika virus, which is transmitted by the bite of infected Aedes mosquitoes. Some women may remain unaware they have the virus, as they may not develop any symptoms. Only one in four people infected with Zika develops symptoms, and in those with symptoms the illness is usually mild.

The most common symptom is exantema, or rash, often accompanied by mild fever. Zika also can cause conjunctivitis, muscle and joint pain, and general malaise, which begins a few days after the bite of an infected mosquito.

Research is being done to determine what effects Zika can have on fetuses. On 28 November 2015, the Ministry of Health of Brazil established a relationship between an increase in cases of microcephaly in newborns and Zika virus infections in the country's northeast.  Health authorities, with support from PAHO and other agencies, are conducting research to clarify the cause, risk factors, and consequences of microcephaly.

Is there a treatment for Zika?

There is no vaccine or specific treatment for Zika infection. For that reason, treatment for all people is limited to relief of symptoms, including pregnant women, who should follow the recommendations of their doctor.

PAHO/WHO recommends that pregnant women, and those who are planning to become pregnant who have been exposed to Zika virus, attend prenatal clinics to get information and monitor their pregnancy, in accordance with national health policies and practices.

What does PAHO recommend for pregnant women living in areas where Zika virus is circulating?

Everyone, including pregnant women and women of childbearing age, should avoid exposure to mosquito bites, for example, by wearing long sleeves and long pants, using mosquito nets during the daytime as well as insect repellents recommended by health authorities and according to the instructions on the label. In every home and its surroundings, it is very important to identify and eliminate potential mosquito breeding sites. 

Given reports of cases of sexual transmission of Zika, pregnant women's sex partners living in or returning from areas where local transmission of Zika virus is known to occur should practice safer sex or abstain (throughout the pregnancy).

Can pregnant women travel to an area where Zika is circulating?

The IHR Emergency Committee on Zika virus, at its meeting March 8, 2016, said that Pregnant women should be advised not travel to areas of ongoing Zika virus outbreaks; pregnant women whose sexual partners live in or travel to areas with Zika virus outbreaks should ensure safe sexual practices or abstain from sex for the duration of their pregnancy. 

For more information see: WHO statement on the second meeting of the Emergency Committee of the International Health Regulations (2005) on the Zika virus and increased neurological disorders and congenital malformations 

More information for those traveling to countries where the virus circulates Zika.

How can you protect pregnant women in areas where Zika is circulating?

To prevent mosquito bites, it is recommended that people who live in areas where there are cases of the disease, as well as travelers and, especially, pregnant women should:   

  • Cover exposed skin with long-sleeved shirts, trousers, and hats
  • Use repellents recommended by the health authorities (and apply them as indicated on the label)
  • During the day, sleep under mosquito nets. 
  • Look for possible mosquito breeding sites and eliminate them.

Pregnant women should attend prenatal checkups in a timely manner.

Pregnant women whose partners live or travel to areas with outbreaks should ensure adopt safe sex or abstain from sex during pregnancy.

For more information, see: 

What does PAHO recommend to women of childbearing age with respect to becoming pregnant in areas where Zika virus is circulating?

PAHO/WHO recommends they take preventive measures to avoid mosquito bites, which in addition to Zika can also transmit diseases such as dengue and chikungunya.

Can it be transmitted from mother to child?

There is more evidence about this type of transmission. Research is currently under way on the risk of mother-to-child transmission of the virus and its possible effects on babies. Pregnant women in general, and particularly those who develop symptoms of Zika virus infection, should be closely monitored by health providers. 

Can mothers with Zika infection breastfeed their baby?

There are currently no documented reports of Zika virus being transmitted to infants through breastfeeding. In countries with ongoing transmission of Zika virus no adverse neurologic outcomes or severe diseases have been reported to date from infants with postnatally acquired Zika infection. Any change to this situation should be carefully monitored.  In light of available evidence, the benefits of breastfeeding for the infant and mother outweigh any potential risk of Zika virus transmission through breast milk.

More information.

Can Zika virus cause congenital malformations, such as microcephaly?

In some Brazilian states where Zika virus has been circulating in recent months, there has been a marked increase in cases of newborns with microcephaly.  Health authorities, with support from PAHO and other agencies, are conducting research to clarify the cause, risk factors, and consequences of microcephaly.

PAHO/WHO recommends that countries continue to provide access to prenatal care for pregnant women. Women who are pregnant or of childbearing age should avoid exposure to mosquito bites.

It's important to keep pregnant women should be kept informed and supported during pregnancy.

More information.

What is microcephaly?

Microcephaly is an uncommon condition whose causes can be genetic or environmental (related to toxicity, radiation or infection). It is defined as a condition at birth in which the newborn's head circumference is less than expected for age and sex. Microcephaly can present as an isolated condition or may be associated with other symptoms such as convulsions, developmental delays or feeding difficulties. These symptoms have varying degrees of severity and in some cases may be life-threatening. 

It is very difficult to predict the consequences of microcephaly at the time of birth, so that close follow-up is needed through check-ups to monitor and evaluate affected babies. There is no specific treatment for microcephaly. Care is centered on follow-up, promotion and maximization of the child's abilities.

How can microcephaly be confirmed in a baby?

The most reliable way to assess whether a baby has microcephaly is to measure head circumference at birth and again 24 hours after birth. Once a baby is diagnosed with microcephaly, a multidisciplinary health team should begin a process of follow-up and monitoring of the child. 

Pregnant women should attend regular prenatal check-ups and receive whatever tests their health providers deem necessary at each stage of pregnancy.

Should women postpone or interrupt pregnancy because of Zika?

It is not known how long Zika outbreaks are likely to continue. Any decision to defer pregnancy is a woman's human right[1]. PAHO urges public health authorities to ensure that women have access to reproductive health services, including contraception, are well informed about personal protection from mosquito bites and about the eventual risks to which they may be exposed. Women should also be informed of the support services they can expect to receive after birth. This information should be communicated to women in a culturally appropriate manner and in a language they understand.

Detecting the Zika virus during pregnancy is a challenge in most countries in the Region. At this time, there is not sufficient evidence to determine the potential risk of a pregnant woman contracting Zika, nor the risk this infection might present to her baby. The national legislation of Member States regarding pregnancy interruption should be taken into account for any decision being made. 

What is PAHO doing to determine the relationship between Zika and these congenital conditions?

PAHO is supporting countries in the region in monitoring and responding to the outbreak of Zika and complications associated with the virus. Several investigations are under way to clarify the causes, risk factors, and consequences of microcephaly. All risk factors are being rigorously tested, including those related to toxicity, medicines, genetic factors and other infectious causes.

PAHO is communicating with all its member countries in the region and promoting messages about prevention and control of vector-borne diseases, with emphasis on personal protection measures that should be taken by pregnant women.

For more information see: PAHO Strategy for Enhancing National Capacity to Respond to Zika Virus Epidemic in the Americas.

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(1) Article 16 of the UN Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW) establishes that women have "the same rights to decide freely and responsibly on the number and spacing of their children and to have access to the information, education and means to enable them to exercise these rights...." Regarding access to family planning methods, Article 12 of CEDAW establishes that "State Parties shall take all appropriate measures to eliminate discrimination against women in the field of health care in order to ensure, on a basis of equality of men and women, access to health care services, including related to family planning...." Article 14 of CEDAW refers to particular measures to protect women in rural areas and establishes that "State Parties shall ensure to such women the right to have access to adequate health care facilities, including information, counselling and services in family planning...." 

 UN Convention on the Elimination of All Forms of Discrimination Against Women entered into force on 3 September 1981 and has been ratified by the following countries of the Americas: Antigua and Barbuda, Argentina, Bahamas, Barbados, Belize, Bolivia, Brazil, Canada, Chile, Colombia, Costa Rica, Cuba, Dominica, Dominican Republic, Ecuador, El Salvador, Grenada, Guatemala, Guyana, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Suriname, Trinidad and Tobago, Uruguay and Venezuela.

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More information on Zika: www.paho.org/zikavirus