Zika virus is a flavivirus transmitted by Aedes (Stegomyia) species of 
mosquitoes. In May 2015, the World Health Organization confirmed the first local 
transmission of Zika virus in the Americas in Brazil. The virus has spread 
rapidly to other countries in the Americas; as of January 29, 2016, local 
transmission has been detected in at least 22 countries or territories, 
including the Commonwealth of Puerto Rico and the U.S. Virgin Islands. Zika 
virus can infect pregnant women in all three trimesters. Although pregnant women 
do not appear to be more susceptible to or more severely affected by Zika virus 
infection, maternal-fetal transmission has been documented. Several pieces of 
evidence suggest that maternal Zika virus infection is associated with adverse 
neonatal outcomes, most notably microcephaly. Because of the number of countries 
and territories with local Zika virus transmission, it is likely that obstetric 
health care providers will care for pregnant women who live in or have traveled 
to an area of local Zika virus transmission. We review information on Zika 
virus, its clinical presentation, modes of transmission, laboratory testing, 
effects during pregnancy, and methods of prevention to assist obstetric health 
care providers in caring for pregnant women considering travel or with a history 
of travel to areas with ongoing Zika virus transmission and pregnant women 
residing in areas with ongoing Zika virus transmission.