There is no proven method to completely prevent placenta previa, a condition where the placenta attaches low in the uterus and covers part or all of the cervix. The underlying cause remains unknown, and no medical organization has issued specific prevention guidelines. That said, several well-studied risk factors are within your control, and understanding them can meaningfully lower your odds.
Why Placenta Previa Happens
Placenta previa occurs when a fertilized egg implants in the lower part of the uterus rather than higher up, where the blood supply is richer. In a healthy uterus, the placenta tends to “migrate” upward as the uterus grows. In fact, among cases identified on second-trimester ultrasound, 84% of complete previas and 98% of marginal previas resolve on their own by about 29 weeks as this natural migration takes place.
When something disrupts the uterine lining, though, this process can go wrong. Scar tissue from previous surgeries creates areas of chronic inflammation and reduced blood flow. Because the scar can’t nourish the placenta adequately, the placenta spreads toward the lower uterus to compensate. Scarring also changes the shape of the uterine cavity, pulling the implantation site closer to the cervix. And in the third trimester, scar tissue in the lower uterine segment can physically block the placenta from migrating upward, keeping it in place over the cervix.
Risk Factors You Can Influence
Cesarean Sections
Previous cesarean delivery is one of the strongest predictors. Every C-section leaves a scar on the uterus, and the risk of placenta previa rises with each additional surgery. By the fifth cesarean, the risk increases by more than 67%. If you’re planning future pregnancies, this is one of the most important factors to discuss with your provider when weighing delivery options. A vaginal birth, when it’s safely possible, avoids adding uterine scar tissue.
Uterine Procedures
Dilation and curettage (D&C), commonly performed after miscarriage or for other gynecological reasons, carries a notable impact. Women who had undergone at least one D&C procedure had more than five times the odds of developing placenta previa compared to women without that history. This doesn’t mean a D&C should be refused when medically necessary, but when alternatives exist for managing a miscarriage or other condition, it’s worth discussing options that minimize instrumentation of the uterus.
Smoking
Cigarette smoking has a clear dose-response relationship with placenta previa: the more you smoke, the higher your risk. Women who smoked 20 or more cigarettes per day were 2.3 times more likely to develop previa than nonsmokers. This is one of the most directly actionable risk factors. Quitting before or early in pregnancy reduces exposure during the critical window when the embryo implants.
Cocaine Use
Cocaine use during pregnancy has also been linked to elevated risk, though the association is weaker than smoking once other factors are accounted for. The estimated odds ratio is about 1.4 compared to nonusers. Still, avoiding cocaine is one of the clearest steps you can take for placental health and pregnancy safety overall.
Assisted Reproductive Technology
Pregnancies conceived through IVF carry a substantially higher rate of placenta previa. At the population level, IVF pregnancies had 17.2 cases per 1,000 births compared to 3.1 per 1,000 for naturally conceived pregnancies. Even when researchers compared pregnancies within the same mother (one conceived naturally, one through IVF), the IVF pregnancy still carried 2.6 times the risk. The reasons likely involve both embryo transfer techniques and the hormonal environment of assisted cycles. If you’re undergoing fertility treatment, this is something to be aware of rather than something that should change your decision, but it underscores the importance of careful monitoring.
Risk Factors You Can’t Change
Some factors that raise your risk are outside your control. Women aged 34 and older have two to three times the risk of placenta previa compared to women under 20, with a steady increase as age rises. Having carried multiple pregnancies also raises the odds, likely because each pregnancy adds some degree of wear to the uterine lining.
If you’ve had placenta previa in a previous pregnancy, the recurrence rate is around 2%. That’s higher than the general population risk but still relatively low, which is reassuring if you’re considering another pregnancy.
What Prevention Actually Looks Like
Because there’s no single intervention that prevents placenta previa, the practical approach is reducing cumulative damage to the uterine lining over your reproductive years. That means:
- Avoiding unnecessary uterine surgeries when safe alternatives exist
- Choosing vaginal delivery when it’s a medically appropriate option, particularly if you plan future pregnancies
- Quitting smoking before conception or as early in pregnancy as possible
- Avoiding recreational drugs, particularly cocaine
None of these steps guarantee you won’t develop placenta previa. Plenty of women with no risk factors at all are diagnosed with it, and the condition can occur in a first pregnancy with no prior uterine history. But each modifiable factor you address chips away at the overall probability.
If You’re Already Pregnant
If a second-trimester ultrasound shows a low-lying placenta, don’t panic. The vast majority of these findings resolve as the uterus expands. Your provider will schedule a follow-up ultrasound, typically around 28 to 32 weeks, to check whether the placenta has moved. For the cases that don’t resolve, management focuses on monitoring for bleeding, limiting activities that could trigger hemorrhage, and planning the safest delivery approach, which is almost always a scheduled cesarean.
The most useful thing you can do at that point is stay informed about warning signs, primarily painless vaginal bleeding in the second or third trimester, and know that early detection through routine ultrasound has made this condition far more manageable than it once was.