causes of miscarriage after heartbeat?

Odds of Miscarrying After Seeing a Heartbeat on Ultrasound

If you are pregnant, have no vaginal bleeding, and are without other risk factors (such as being older, smoking, drinking, or having an infection), research suggests that your odds of having a miscarriage are lower after a fetal heartbeat has been detected by ultrasound.1

Learn more about the common risk factors for first- and second-trimester miscarriage and how that risk decreases once the heartbeat is seen. Beyond the fetal heartbeat, we provide an overview of early developmental milestones you can expect during the first trimester of your pregnancy.

Risk of miscarriage after seeing heartbeat:2

Overall risk: 4%
After 8 weeks: 1.6%

Miscarriage After Seeing a Heartbeat

There are several different factors that may affect your risk of a miscarriage in the first or second trimester of your pregnancy. Seeing your baby's heartbeat on an ultrasound is usually a good sign and typically lowers your risk of having a miscarriage.
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 the parent's sperm or egg which can be either hereditary or spontaneous. Around half of miscarriages are linked to chromosomal issues and most happen randomly and are not due to either parent's health.3

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. RESOLVE: The National Infertility Association says there's an increased risk for women with a history of recurrent miscarriages. According to their estimates, 5% of women who get pregnant will experience at least 2 consecutive miscarriages.4

If you are 35 and older, you have a more significant miscarriage risk even though your risk does drop after detecting a heartbeat.
Are Ultrasounds an Accurate Way to Find a Baby's 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.5

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. This condition can be treated with cervical cerclage.
How an Incompetent Cervix May Lead to a Miscarriage
Fetal Development Milestones

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.6
Week 5

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.7
Weeks 6–9

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, earbuds, and spine begin to form and the blood begins to circulate.

During week eight, your baby's arms start to grow longer. The hands and feet look like paddles and the lungs start to form. By week nine of your pregnancy, all of your baby's organs have started to grow. Additionally, hair follicles begin to develop, as well as your baby's toes.
Weeks 10–14

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. During weeks 11 through 14, the genitals begin to develop and the face is well-formed.
Weeks 15–18

Your baby's liver and pancreas form. At this stage the skin is transparent and the baby starts to make sucking motions. The reproductive organs are now fully formed. The fetus can start to suck their thumb, stretch, and yawn. The pregnant parent may begin to feel a gentle fluttering. That is their baby moving around.
A Word From Verywell

It's natural to feel anxious about the health of your developing baby. But if their heartbeat has been detected by ultrasound, that is a positive sign that things are progressing well. Research shows the risk of miscarriage is reduced once the baby's heartbeat is seen.

But don't panic if you don't see the heartbeat right away. It doesn't necessarily mean there is a problem with the pregnancy. There are several non-emergency reasons why this happens. As always, if you have any questions, concerns, or signs of a problem, do not hesitate to contact your healthcare provider right away.