Placenta Previa
Placenta covers part or all of the cervix, blocking baby's exit and requiring C-section delivery.
Affects: Affects 1 in 200 pregnancies at term
Overview
Placenta previa occurs when the placenta implants low in the uterus and covers part or all of the cervix. This blocks the baby's exit route and makes vaginal delivery dangerous due to bleeding risk.
Many cases of low-lying placenta diagnosed early in pregnancy resolve as the uterus grows and the placenta "moves up." True placenta previa at term requires C-section delivery.
The main danger is bleeding, which can occur without warning in the third trimester. Women with placenta previa need careful monitoring and may require early delivery if severe bleeding occurs.
🩺 Symptoms
- •Bright red vaginal bleeding without pain (usually third trimester)
- •Bleeding that stops and starts
- •Bleeding may be light or heavy
- •Some women have no symptoms (discovered on ultrasound)
- •Cramping or contractions may accompany bleeding
🔍 Causes
- →Placenta implants low in uterus
- →Exact cause often unknown
- →May relate to uterine scarring
- →Abnormal uterine lining
- →Multiple embryos attaching
⚠️ Risk Factors
- •Previous C-section or uterine surgery
- •Previous placenta previa
- •Multiple pregnancy (twins, triplets)
- •Previous abortion or D&C
- •Maternal age over 35
- •Smoking
- •Cocaine use
- •Multiple previous pregnancies
- •Infertility treatment/IVF
- •Asian ethnicity
🔬 Diagnosis
- →Ultrasound diagnosis (often 20-week anatomy scan)
- →Transvaginal ultrasound for more accurate placental location
- →Follow-up ultrasounds to see if placenta moves up
- →Types: Complete (covers entire cervix), Partial (covers part), Marginal (edge reaches cervix)
- →Low-lying placenta: within 2cm of cervix but not covering
💊 Treatment
- ✓Early pregnancy: Observation, usually resolves as uterus grows
- ✓Pelvic rest: No sex, no tampons, no vaginal exams
- ✓Activity restriction if bleeding occurs
- ✓Hospitalization for heavy bleeding
- ✓Blood transfusions if severe blood loss
- ✓Corticosteroids for baby's lung development if early delivery likely
- ✓Scheduled C-section at 36-37 weeks
- ✓Emergency C-section if severe bleeding
- ✓May need hysterectomy if severe bleeding can't be controlled
🛡️ Prevention
- →No proven prevention methods
- →Avoid smoking
- →Treat any uterine abnormalities before pregnancy
- →Space pregnancies to allow uterine healing
⚠️ Potential Complications
- !Severe bleeding requiring blood transfusion
- !Preterm birth
- !Placenta accreta (placenta grows into uterine wall)
- !Emergency hysterectomy
- !Maternal death (rare)
- !Baby complications from preterm birth
- !Risk of bleeding during C-section
🚨 When to Call Your Doctor
Contact your healthcare provider immediately if you experience:
- ⚠Any vaginal bleeding in second half of pregnancy
- ⚠Heavy bleeding or bleeding that soaks a pad
- ⚠Bleeding with cramping or contractions
- ⚠Dizziness, lightheadedness, or fainting
- ⚠Fast heartbeat
- ⚠Severe pain
- ⚠Immediately call 911 if severe bleeding
Related Conditions
This information is for educational purposes and should not replace medical advice. Always consult your healthcare provider for personalized guidance.