One of the most common problems spotted at the 20 week ultrasound is placenta previa. Placenta previa is where the placenta is nearby, or actually covering some or all of the cervix. It’s a potentially dangerous condition because if the placenta covers the cervix, it blocks baby’s way out, requiring a cesarean section to deliver the baby. And more seriously, as the cervix dilates towards the end of pregnancy, the placenta can be torn and bleed, which can be life-threatening to mom and baby.

Complete or partial placenta previa, where the placenta covers at least a quarter, or even all of the cervix, occurs in around 1 in 200 pregnancies, and requires careful monitoring by your doctor.

And more common is a marginal placenta previa, where the placenta is close by, or touching the cervix, but not actually covering it.

At 20 weeks, when the placenta is relatively large compared to the size of the uterus, many women appear to have placenta previa. The ultrasound technician will note the position of the placenta, so your doctor is aware and can discuss it with you. The doctor will probably tell you to avoid intercourse, heavy lifting, and strenuous activity. Your husband will be thrilled that he has to do the vacuuming instead of sex.

Several moms I know, including me, had marginal placenta previa at 20 weeks. At my next obstetrician appointment, the doctor explained what it was. The position of the placenta is largely random, but there are risk factors to placenta previa, including previous cesarean sections, a history of placenta previa, and it’s more common in older moms. Apparently, smoking or using cocaine also increases the risk, my doctor told me, raising one eyebrow. What? I’ve never smoked and the only kind of coke I know comes in a red can with a swirl on it.

The good news is that for most women who have marginal placenta previa at 20 weeks, as your uterus grows, the placenta gets further from the cervix and you’ll likely be given the all-clear to get back to normal activities by 24-28 weeks. Your doctor will schedule another ultrasound to check the position of the placenta at that time. If the placenta is now clear of the cervix, then vaccuming, etcetera are back on.

I had another ultrasound at 25 weeks, and like 90% of moms with marginal placenta previa at 20 weeks, my placenta was in a normal position, and the rest of my pregnancy went smoothly, except for having to think of other excuses to not vacuum.

If you are pregnant, and experience any vaginal bleeding, get checked by a doctor asap. If you have been told you have, or may have placenta previa, it is important to let the doctor who examines you know, as they will need to take extra precautions when they examine you to avoid causing any damage to your placenta.

During pregnancy, your body creates a temporary organ called the placenta. The placenta is necessary during pregnancy in order for your baby to grow and be healthy. After the birth of your baby, your doctor or midwife will also have you deliver the placenta, as it is no longer needed.

The placenta is created during the first trimester but is not fully functional until the second trimester when it takes over all the nutrient production and waste management for the baby. The placenta is both genetically and biologically composed of two equal parts from the fetus and the mother. It is connected to the uterine wall and connected to the baby through the umbilical cord. It receives nutrients and oxygen and filters out any waste from the mother’s blood before delivering the blood to the baby via the umbilical cord.

Until the placenta takes over, a woman naturally produces progesterone to keep the baby viable. As soon as the placenta takes over it starts creating its own progesterone to sustain the pregnancy. After delivery of the placenta the cord is clamped near the baby and cut off permanently disconnecting the baby from the placenta. The entrance of the umbilical cord into the baby’s body later becomes the baby’s belly button.

Some cultures practice placentophagy which is the eating of the placenta. Those who do this believe that eating the placenta helps prevent postpartum depression and other complications. However, modern doctors and midwives do not believe that eating the placenta will actually help reduce the occurrence of postpartum depression.

In some pregnancies, placenta previa can occur. Placenta previa is a condition where the placenta covers at least part of the cervix, which is the opening that the baby will come through when born vaginally. This happens in about one of every 200 pregnancies. There are 3 types of placenta previa.

• Complete
  Complete placenta previa is the placenta covering the entire cervix. This can cause bleeding throughout the pregnancy, growth retardation and congenital defects in baby. It will also mean that a woman will need a c-section when it comes time to deliver her baby.
   
• Partial
  Partial placenta previa is a partial covering of cervix is covered. This can be anywhere from 1/4 to 3/4 of the cervix. This can also cause bleeding and may lead to a c-section.
   
• Marginal
  Marginal placenta previa occurs when just a small portion, or just the edge of the cervix, is covered. In this case, as the pregnancy progresses, the placenta will generally move up and out of the way, allowing a clear passage for the baby to be born vaginally.

If you experience bleeding during your pregnancy, you should talk to your doctor and rule out the possibility of any bleeding being caused by placenta previa.