Causes

Vaginal bleeding during pregnancy has many causes. Some are serious, and many aren't.

1st trimester

Possible causes of vaginal bleeding during the first trimester include:

• Ectopic pregnancy (in which the fertilized egg implants and grows outside of the uterus, such as in a fallopian tube)
• Implantation bleeding (which occurs about 10 to 14 days after conception when the fertilized egg implants in the lining of the uterus)
• Miscarriage (the spontaneous loss of pregnancy before the 20th week)
• Molar pregnancy (a rare occurrence in which an abnormal fertilized egg develops into abnormal tissue instead of a baby)
• Problems with the cervix, such as a cervical infection, inflamed cervix or growths on the cervix

2nd or 3rd trimester

Possible causes of vaginal bleeding during the second or third trimester include:

• Incompetent cervix (a premature opening of the cervix, which can lead to preterm birth)
• Miscarriage (before the 20th week) or intrauterine fetal death
• Placental abruption (when the placenta — which supplies nutrients and oxygen to the baby — separates from the wall of the uterus)
• Placenta previa (when the placenta covers the cervix, resulting in severe bleeding during pregnancy)
• Preterm labor (which might result in light bleeding — especially when accompanied by contractions, dull backache or pelvic pressure)
• Problems with the cervix, such as a cervical infection, inflamed cervix or growths on the cervix
• Uterine rupture, a rare but life-threatening occurrence in which the uterus tears open along the scar line from a prior C-section

Normal vaginal bleeding near the end of pregnancy

Light bleeding, often mixed with mucus, near the end of pregnancy could be a sign that labor is starting. This vaginal discharge is pink or bloody and is known as bloody show.