Placenta previa is diagnosed in .5% of all US pregnancies each year and is considered relatively rare. It is different than a “low-lying” placenta as to be clinically decided as previa, the placenta needs to be within 2cm of the cervical os (the opening of the uterus to the cervix). There are generally three types of placenta previa: complete, partial, and marginal. With placenta previa, placental attachment is disrupted as the pregnancy progresses since the lower uterine area gradually thins in preparation for the onset of labor; this leads to bleeding at the implantation site, because the uterus is unable to contract adequately and stop the flow of blood from the open vessels. It usually is diagnosed via ultrasound early on in the pregnancy and typically presents as painless vaginal bleeding continuing into the second and third trimesters. Spotting or bleeding in the first trimester is often implantation bleeding – but always verify with your doctor if something like this occurs.

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Risk factors include:

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Advancing maternal age (>35 y)

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Infertility treatment

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Women who have been pregnant multiple times (to birth or not)

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Pregnancies involving more than 1 fetus

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Decreased time in between pregnancies

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Previous uterine surgery, uterine insult or injury

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Previous cesarean delivery (**one of the highest risk factors)

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Previous or recurrent abortions

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Previous placenta previa (4-8%)

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Smoking

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Cocaine use

 

Though this does not completely reflect on placenta previa specifically, 90% of all low-lying placentas tend to resolve naturally. This is due to the placenta “growing away” from the cervical os as the pregnancy progresses. Placenta previa has the potential for maternal complications such as (but not limited to) hemorrhage, placenta accrete/increta/percreta, placental abruption, preterm delivery, postpartum endometritis, cervical or vaginal lacerations, spontaneous abortion, and infection. If that isn’t enough to worry about, placenta previa also can present with fetal complications that include congenital malformations, intrauterine growth restriction, fetal anemia, abnormal fetal position in the uterus, low birth weight, neonatal respiratory distress syndrome, jaundice, and increased rise for SIDS.

 

If you experience any bleeding during your pregnancy, at any time, it is suggested you reach out to your physician immediately. Given the stats, it isn’t likely every bleeding occurrence leads to diagnosis of placenta previa but being well informed and examined is always in the best interest of mother and baby! I experienced this first-hand with my second pregnancy, so if you feel you need someone to talk to about this, please don’t hesitate to reach out to me personally.