From the Center for Disease Control...
Travelers have returned from certain areas of Southeast Asia with Zika virus infection. While our understanding of the complications of Zika virus infection continues to evolve, and pending broader international surveillance efforts for Zika virus infection, we are providing pregnant women and their partners updated recommendations on reducing their risk for travel related Zika virus infection. CDC recommends pregnant women should consider postponing non essential travel to Southeast Asia countries with reports of Zika virus infection from local transmission or related to travel to those countries, and those countries with adjacent borders where limited information is available to fully evaluate risk of Zika virus infection.
My take: Unfortunately, good surveillance and identification of diseases such as Zika may be compromised in many areas of the world. Is testing as thorough as we would expect - probably not. Pregnancy and Zika provide potentially a lifelong dangerous situation to the unborn child - and taking a conservative stand would be to postpone the trip until the baby is born.
There are so many places in this world that do not carry a risk - so why take the chance? If your wife should be an unfortunate one who contracts Zika... and it causes problems with your little one that can be lifelong and devastating - how would you feel knowing you chose to travel there? If, however, you choose to travel... very strict insect repellant applications and avoiding areas that might harbor mosquitoes... extreme diligence is imperative.
The CDC has good information on mosquito avoidance measures. www.cdc.gov/travel