Diagnoses of "complications of pregnancy, childbirth, and the puerperium" (ICD-9-CM: 630-679) include both morbid complications and indications for routine care of pregnant women. During 2001-2010, U.S. service members with live births (n=156,314) had 1.16 million medical encounters with primary diagnoses of "pregnancy complications". The most frequent diagnoses were "other current conditions", "other threatened labor" (e.g., false labor), "previous cesarean delivery" and "normal delivery". The number of complication-related medical encounters per pregnancy more than doubled during 2001-2010. Diagnoses of gestational diabetes, previous cesarean delivery and advanced maternal age contributed to the largest increases in pregnancy-related medical encounters during the period. The complications that accounted for the largest increases in the percents of pregnancies affected by them were urinary tract infections, fetal heart rate/rhythm abnormalities and back pain in pregnancy.