Odds of Miscarrying After Seeing Heartbeat on Ultrasound

A baby's heart rate can be detected around six weeks

fetal ultrasound
Lawren/Moment/Getty Images

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

Risk Factors Associated With Miscarriage After Seeing a Heartbeat

If you are pregnant, have no vaginal bleeding, and are without other risk factors, most estimates suggest that your odds of having a miscarriage after seeing a fetal heartbeat are about 4 percent.

 If you are experiencing vaginal bleeding but have an otherwise low-risk pregnancy and a fetal heartbeat was detected on ultrasound, your risk of miscarriage might be around 13 percent, one study found. 

Another study determined that around 17 percent of women with a history of recurrent miscarriages will miscarry after seeing a heartbeat on the ultrasound.

If you are 35 and older, you have a more significant miscarriage risk after the ultrasound detects a heartbeat, even though your risk does drop after detecting a heartbeat. One study found that women over 36 have a 16 percent risk of miscarriage at this point, and women over 40 have a 20 percent risk.

Fetal Physiology Explained

Fetal heartbeat is an extremely important step your baby's development. After all, we need our hearts to pump blood and survive. Here are some other notable things that happen around the first trimester of gestation.

Week five of your 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.

Week 5 is a rapid period of growth for your baby. During week five, your baby is most sensitive to teratogens or things that may cause birth defects, such as illicit drugs, certain medications, and infections.

Weeks six and seven of your pregnancy: During weeks six and seven your baby's heart begins to grow and beat at a regular rhythm. At this time, your baby's eyes, ear buds, and spine begins to form and their blood begins to circulate. 

Week eight of your pregnancy: During week eight of your pregnancy, your baby's arms start to grow longer. Additionally, their hands and feet look like paddles and their lungs start to form.

Week nine of your pregnancy: During 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 of your pregnancy: 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 of your pregnancy: During these weeks, the genitals begin to develop and the face is well formed.

Weeks 15 to 18 of your pregnancy: Your baby's liver and pancreas form. At this stage their skin is transparent and they start to make sucking motions.

Sources:

Hill, L.M., D. Guzick, J. Fries, J. Hixson, "Fetal loss rate after ultrasonically documented cardiac activity between 6 and 14 weeks, menstrual age." Journal of Clinical Ultrasound May 1991. 

Smith, K.E. and R.P. Buyalos, "The profound impact of patient age on pregnancy outcome after early detection of fetal cardiac activity." Fertility and Sterility Jan 1996. 

Van Leeuwen, Ingeborg, D. Ware Branch, and James R. Scott, "First-Trimester Ultrasonography Findings in Women With a History of Recurrent Pregnancy Loss. American Journal of Obstetrics and Gynecology 1993. 

 

Continue Reading