Ectopic, or tubal, pregnancies almost tripled -- from 55,000 in 1991 to 150,000 in 2001 -- and experts blame sexually transmitted diseases (STDs), especially chlamydia and gonorrhea.
"STDs can scar and narrow the fallopian tubes, making it harder for a fertilized egg to move down to the uterus. The egg then ends up growing in the wrong place," says Jeanna Piper, M.D., an ob-gyn at the University of Texas Health Science Center at San Antonio.
Preventing ectopic pregnancies is almost impossible, so early detection is key. At your first prenatal visit, tell your doctor if you've had an STD or a previous ectopic pregnancy. And watch for these symptoms in the first 10 to 12 weeks of pregnancy: cramps and tenderness in the lower abdomen, brown spotting or light bleeding, nausea, vomiting, dizziness, or weakness.