Odds of Miscarrying After Seeing a Heartbeat on Ultrasound

Fetal ultrasound
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Seeing your baby's heartbeat on an ultrasound is usually a good sign and typically lowers your risk of having a first-trimester miscarriage. Physicians generally agree that the risk of miscarriage decreases once the pregnancy reaches a point that an ultrasound can detect a heartbeat, which is about six weeks of gestation. The exact amount that it decreases, however, varies.

The most common cause of pregnancy loss is chromosomal problems—in other words, the embryo is not viable. Seeing a heartbeat indicates that the embryo was able to form a functioning heart.

If you are pregnant, have no vaginal bleeding, and are without other risk factors (such as being older, smoking, drinking, or having an infection), most estimates suggest that your odds of having a miscarriage after seeing a fetal heartbeat are about 4%. The risk drops each week of gestation from week six through nine. One study found the overall risk—past eight weeks, with a normal prenatal visit—to be 1.6% or less.

Risk of miscarriage after seeing heartbeat:

  • Overall risk: 4%
  • After 8 weeks: 1.6%

Miscarriage After Seeing a Heartbeat

There are some factors that raise the risk of miscarriage after a heartbeat is detected. These include whether you are experiencing vaginal bleeding but have an otherwise low-risk pregnancy. The Miscarriage Association notes that an older study also found an increased risk for women with a history of recurrent miscarriages.

If you are 35 and older, you have a more significant miscarriage risk even though your risk does drop after detecting a heartbeat.

Second-Trimester Miscarriage

Having an incompetent cervix is the most common cause of second trimester loss. Also called "cervical insufficiency," this is a condition in which the cervix weakens and dilates too early, leading to pregnancy loss or (depending on the length of gestation) pre-term delivery.

If a pregnant woman has a history of incompetent cervix, seeing a heartbeat doesn’t reduce the risk of this particular cause of miscarriage. For this, prenatal care early on is essential.

Fetal Physiology Explained

Fetal heartbeat is an extremely important step in your baby's development. Here are some other notable things that happen during the first trimester of gestation.

  • Week five of pregnancy: This week marks the beginning of the embryonic period. During the embryonic period, your baby's major systems and structures start to develop. Your baby's external features also begin to develop during week five. The fifth week is a period of rapid growth for your baby. During week five, your baby is most sensitive to teratogens (things that may cause birth defects) such as illicit drugs, certain medications, and infections.
  • Weeks six and seven: Your baby's heart begins to grow and beat at a regular rhythm. At this time, your baby's eyes, earbuds, and spine begin to form and the blood begins to circulate.
  • Week eight: Your baby's arms start to grow longer. The hands and feet look like paddles and the lungs start to form.
  • Week nine: All of your baby's organs have started to grow. Additionally, hair follicles begin to develop, as well as your baby's toes.
  • Week 10: At end of the tenth week of pregnancy, your baby is no longer an embryo and is instead called a fetus. In other words, your baby has exited the embryonic stage. During this week of pregnancy, your child's eyelids and outer ears begin to form and the intestines rotate.
  • Weeks 11 to 14: During these weeks, the genitals begin to develop and the face is well-formed.
  • Weeks 15 to 18: Your baby's liver and pancreas form. At this stage the skin is transparent and the baby starts to make sucking motions.
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