Not Medical Advice:
While you should always consult with a medical professional about any type of drug intake during pregnancy, even simple OTC drugs, we can tell you that taking 100mg Doxycycline (imprint: West-ward 3142) can be dangerous during pregnancy!
According to the FDA: Doxycycline should not be used during pregnancy unless the benefit outweighs the risk.
Animal studies have shown evidence of embryotoxicity and fetotoxicity, including toxic effects on skeletal formation. They also indicate doxycycline crosses the placenta and is found in fetal tissues. There are no controlled data for human pregnancy, but congenital defects have been reported with the use of tetracyclines.
The Daytona Times is reporting that doxycycline, a decades-old antibiotic, is in short supply, and has spiked in price some 6,100 percent, going from about 6¢ per tablet in 2012 to $3.65 by the end of 2013!