No Heartbeat at 6 Weeks — What It Means and What Happens Next

Your dates may be different from your development — this is the commonest reason. Pregnancy is dated from the first day of your last period, which assumes ovulation happened around day 14. In practice, ovulation varies widely between women and between cycles: implantation timing, an irregular or longer cycle, or simply a later ovulation can leave you a week or more “behind” your calculated dates. A pregnancy measuring five weeks when the calendar says six and a half is developing perfectly normally — it is the calendar that is out, not the pregnancy. This is why what the scan measures matters far more than what the dates say.

The type of scan makes a real difference. A transvaginal scan places the probe much closer to the uterus and sees detail one to two weeks earlier than scanning through the abdomen. At six weeks, an abdominal scan may show very little even in a completely healthy pregnancy, which is why transvaginal scanning is standard this early — our first-time guide explains what it involves.

Normal biological variation. Cardiac activity typically becomes visible somewhere between about five and a half and six and a half weeks, and embryos do not all reach the same milestone on the same day. A few days either side of the average is ordinary human variation, not a warning sign.

Practical and technical factors. The position of the uterus (a tilted or retroverted uterus sits further from the probe), fibroids, previous abdominal surgery, or scanning conditions can all make a very small embryo harder to see clearly. These are limitations of the view obtained, not findings about the pregnancy — and an honest report says which it is.

And, honestly: sometimes a heartbeat is not seen because the pregnancy has stopped developing — an early miscarriage. That possibility is real, and this page does not pretend otherwise. But at six weeks it cannot be distinguished from the explanations above on a single scan, which is exactly why the criteria below exist.

The embryonic heart begins as a simple tube and starts beating remarkably early — around three weeks after conception, well before it can be seen on any scan. Visibility, not existence, is what a six-week scan is testing.

Heart rate also changes rapidly across these weeks — roughly 100–120 beats per minute when first detectable at five to six weeks, rising to around 140–170 by eight to nine weeks. A rate that seems “slow” at six weeks is often simply an early rate, and our guide to normal fetal heart rate by week sets out the ranges. If you are further along than six weeks, the sibling guides for seven weeks and eight weeks address those windows specifically, where the picture is clearer and the thresholds bite sooner.

Sometimes the repeat scan confirms that the pregnancy has ended. If that happens, a few things are worth knowing plainly. Early miscarriage is common — the NHS estimates around one in eight pregnancies known to the woman end this way, and the true figure including very early losses is higher. It is almost never anyone’s fault: the large majority are caused by chromosomal changes in the embryo that were present from the start, and nothing you did, ate, lifted or felt caused it. Having one early miscarriage does not mean you will have another.

You will be offered choices about what happens next — waiting for things to happen naturally, medication, or a short procedure — and there is usually no rush to decide. Our guide to early ultrasound and miscarriage covers the process in more detail.

And support exists specifically for this. Tommy’s runs a dedicated pregnancy loss support line staffed by midwives, and we keep a list of baby loss helplines including organisations offering counselling and peer support. Using them early is not an overreaction — this is a bereavement, and it deserves to be treated as one.