Is no fetal heartbeat at 6 weeks of pregnancy a sign of miscarriage?

Miscarriage is one of the most stressful situations for a couple who are trying hard for conceiving. Such couples if achieve pregnancy but no fetal heartbeat is visible, can assume the condition as a miscarriage. Is it really so? In this blog, Dr. Nishant Dixit, a highly experienced Reproductive Medicine Specialist will explain how and at what time embryos grow in the uterus and what is delayed conception? Moreover, causes of no heartbeat at 6-week conception are also discussed, and how the couple should proceed in such a situation?

In 15–20% cases out of 100 pregnancies, the fetal heartbeat is not detected within 6 weeks of internal sonography. The situation can be very depressing because couples who have conceived but there’s no fetal heartbeat, such couples begin to panic as they generally interpret it as a pregnancy loss. Such couples always think about what can be done to bring the heartbeat of the baby. To understand the process of fetal heartbeat detection, it is important to know the timeline of naturally conceived pregnancy and how different milestones are achieved in the process.

Heartbeat detection in natural pregnancy

For example, if ovulation in women occurs on the fourteenth day, then after 5-7 days, the embryo begins to develop in the fallopian tube and thereafter it rolls down to the uterus and is implanted in the uterus wall. As soon as the embryo is implanted, the embryo’s cells begin to divide and secrete a hormone called beta-hCG. Due to the effect of this hormone, the woman stops menstruating.

At this time, four weeks of pregnancy are completed and if internal sonography is done at this time, then the membrane of the Gestational Sac should be visible in it. After 1 week, the Yolk Sac should also be visible inside the Gestational Sac. At 6 weeks the fetal heartbeat should be visible along with the yolk sac inside that g sac. This is a normal timeline for a naturally conceived pregnancy but sometimes in the case of late pregnancy, this timeline can change. For example, if ovulation occurs on the 18th or 20th day in a woman, then this timeline shifts 1 week further. The gestational sac is visible within 5 or 6 weeks instead of 4 weeks and the yolk sac appears in 6 or 7 weeks. The fetal heartbeat occurs at 7 or 8 weeks.

Heartbeat detection in IVF pregnancy

In some pregnancies, the exact time of implantation can be identified. For instance, pregnancy is achieved through Assisted Reproductive Techniques like In Vitro Fertilization (IVF). In the case of IVF pregnancy, the right time of implantation can be found out and at 6 weeks, fetal heartbeat can be detected. But if no heartbeat is seen, couples should wait for one week for the heartbeat to appear. This happens in 10-15% of cases. But if after one week also no heartbeat is visible, then there are no chances of fetal heartbeat and it can be a pregnancy loss. Such kinds of pregnancies are known as Blighted Ovum and no supportive treatment or medication is provided as there is a low possibility of a healthy pregnancy.

Why there is no heartbeat in a baby within 6 weeks of pregnancy?

This is one of the most common questions asked by couples. In 90% of cases, the genetic abnormality is one major reason. Thus, couples are advised to undergo genetic investigation, uterus examination, and blood tests along with some hormonal tests to find the accurate reason for the delayed heartbeat in the fetus.

In Brief

The couple should not worry in case the fetal heartbeat is not visible at 6 weeks in the internal sonography. This can be due to the late conception of pregnancy. It is suggested to wait for 1-2 weeks as there are good chances for detection of fetal heartbeat in case of delayed conception.

  • Dr. Nishant Dixit
  • DNB (OBGY), MNAMS
  • Fellowship in Reproductive Medicine
  • Director, Nishant Fertility Centre
  • Reproductive Medicine Specialist

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