Women up to the 34th week of gestation can travel Space-A unless medically inadvisable by your doctor. Women who are 6 weeks or more post partum and infants at least 6 weeks old may travel unless medically inadvisable by your doctor. Infants under 6 weeks old and women who are less than 6 weeks post partum may travel if considered medically sound and so certified in writing by a responsible medical officer or civilian physician. Infants require a DoD ID Number or Passport as identity. SSN is no longer acceptable (as of January 2017). If going overseas to a foreign country then the infant needs a passport. If going to Guam then proof of U.S. Citizenship (Passport or Birth Certificate) is required.