First-Trimester Bleeding

If you have vaginal bleeding at any time during pregnancy, report it to your doctor immediately. Vaginal bleeding can be a sign of miscarriage or premature labor during a pregnancy. But sometimes it is not, particularly in the first trimester.

During the first trimester of pregnancy:

• Vaginal bleeding during pregnancy is more common in women who have previously been pregnant than in women who are pregnant for the first time.
• Very early spotting is sometimes the result of the fertilized egg implanting in the uterus. Implantation takes place 6 to 10 days after the sperm fertilizes the egg.
• Bleeding can be a sign of miscarriage. Early bleeding during the first 6 weeks or so can be an early miscarriage called a blighted ovum. Although a gestational sac has developed, the fertilized egg has not developed into an embryo. This is usually caused by a chromosomal error in the early stages of cell formation. On an ultrasound, a blighted ovum is likely to look like an empty sac attached to the uterine wall.