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Zika and Pregnancy

What is known about the effects of Zika virus on pregnant women?

We expect that the course of Zika virus disease in pregnant women is similar to that in the general population. No evidence exists to suggest that pregnant women are more susceptible or experience more severe disease during pregnancy. It is not known if pregnant women are more susceptible to Guillain-Barré syndrome. Zika virus infection during pregnancy can cause congenital microcephaly and other severe brain defects in fetuses and infants. It has also been linked with other adverse pregnancy and birth outcomes.

Is there any association between Zika virus infection and congenital microcephaly?

We know that Zika virus infection during pregnancy is a cause of congenital microcephaly and other severe fetal brain abnormalities.

Studies are underway to investigate the full spectrum of outcomes of Zika virus infection during pregnancy, including the role of other factors (e.g., prior or concurrent infections, nutrition, and environment).

Is there any known association between maternal Zika virus infection and other adverse pregnancy outcomes?

In addition to severe microcephaly, a pattern of other birth defects, called congenital Zika syndrome, has emerged, which is unique to fetuses and infants infected with Zika virus before birth. This pattern includes thin cerebral cortices with subcortical calcifications; macular scarring and focal pigmentary retinal mottling; congenital contractures, such as clubfoot; and hypertonia restricting body movement soon after birth.

Zika virus has been linked additional problems in infants, but here is more to learn. Researchers are collecting data to better understand the extent to which Zika virus affects mothers and their children. Scientists continue to study how Zika virus affects mothers and their children to better understand the full range of potential health problems that Zika virus infection during pregnancy may cause.

What is the risk of adverse pregnancy or birth outcomes for women infected with Zika virus around the time of conception?

There is limited information available about the risk of periconceptional Zika virus infection. Early case reports suggest there may be adverse outcomes associated with Zika virus infection in early pregnancy, including pregnancy loss and severe microcephaly. Information from other viral infections occurring around the time of conception indicate there are associations between periconceptional infections and adverse outcomes, although timing of infection and conception in these cases was often unknown.

How should pregnant patients who are considering travel to an area with active Zika virus transmission be counseled?

CDC recommends that pregnant women not travel to an area with active Zika virus transmission. If a pregnant women is considering travel to one of these areas, she should talk to her healthcare provider. If she travels, she should be counseled to strictly follow steps to avoid mosquito bites during the trip, and reduce exposure to possible sexual transmission of the virus. If a pregnant woman has a partner who lives in or has traveled to an area with Zika, she should be counseled to use a condom correctly and consistently every time she has sex, or abstain from sex (vaginal, anal, and oral sex, and sharing of sex toys) for the duration of her pregnancy.

How should pregnant women whose partners have Zika virus infection be counseled?

Given the potential risks of maternal Zika virus infection, for pregnant women whose partners have or are at risk for Zika virus infection, using condoms consistently and correctly to prevent infection, or abstaining from sex (vaginal, anal, and oral sex, and sharing of sex toys) for the duration of pregnancy is recommended. Recommendations will be updated as more information becomes available.

Should amniocentesis be considered for diagnosis of congenital Zika virus infection?

Consideration of amniocentesis should be individualized based on the patient’s clinical circumstance. As for the evaluation of other congenital infections, amniocentesis may be considered in the evaluation of potential Zika virus infection. Healthcare providers should discuss the risks and benefits of amniocentesis with their patients.

What is not known about amniocentesis as a clinical tool to diagnose congenital Zika virus infection?

  • The optimal time to perform amniocentesis to diagnose congenital Zika virus infection is not known.
  • It is not known how sensitive or specific tests of amniotic fluid are for congenital Zika virus infection.
  • It is not known if a positive result is predictive of a subsequent fetal abnormality.
  • If a positive result is predictive, it is not known what proportion of infants born after infection will have abnormalities.

If amniocentesis is to be considered in the evaluation for potential Zika virus infection, when should it be performed?

Amniocentesis is not recommended until after 15 weeks of gestation. Amniocentesis performed at ≥15 weeks of gestation is associated with lower rates of complications than when performed at earlier gestational ages (≤14 weeks of gestation). However, the optimal time to perform amniocentesis to diagnose congenital Zika virus infection is not known and should be individualized according to the patient’s clinical circumstances. Referral to a maternal-fetal medicine specialist may be warranted. Healthcare providers should discuss the risks and benefits of amniocentesis with their patients.

How would the results of amniotic fluid testing for Zika virus inform clinical management of pregnant women?

A positive Zika virus rRT-PCR result from amniotic fluid might indicate fetal infection. This information would be useful for pregnant women and their healthcare providers to assist in determining clinical management (e.g., antepartum testing, scheduling serial ultrasounds, delivery planning). Although a negative Zika virus rRT-PCR result from amniotic fluid does not exclude congenital Zika virus infection, it may prompt a work-up for other causes of microcephaly (e.g., other infections, genetic disorders).

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