When does a baby develop a heartbeat

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Hearing your baby’s heartbeat for the first time is one of life’s real joys, something that can often bring parents to tears. It certainly did for us. It’s one of the reasons not to miss the ultrasound scans past the first one at 12 weeks, even though you know everything is OK the anticipation of hearing the heartbeat is too much to resist. However, a fetal heartbeat does exist long before you get a chance to hear it – but when does the baby develop a heart and what was pumping blood before that?

This article explains it all about the beginnings of the fetal heartbeat and its role in the early weeks of pregnancy.

When does a baby grow a heart and when does it beat?

Your baby begins to grow their heart (or the mother grows, depending on how you look at it) around week 3 of gestation and begins to beat at week 4 of gestation. Because there is a 14 day (approximately) window between a period ending and ovulation this will be week 5 and 6 of pregnancy from the date of your last period.

This development coincides with a lot of mothers reporting morning sickness and a general feeling of ‘being pregnant’. The heart is microscopic in size, the embryo itself will only be 2mm long at week 5.

The heart is one of the first organs to develop as it’s important to build the other organs. By week 8 all organs are developed and the embryo is then classified as a foetus. Despite being small and the existence of the placenta it still plays a vital role.

What does a fetal heart do?

The relationship between the fetal heart and the nutrients in the placenta is a complicated one, one we’d describe as symbiotic. Essentially, it all comes down to the oxygen flow. Before a baby is born they do not use their lungs as they are completely submerged in liquid; so they can’t get their own supply of oxygen through breathing. Instead, the placenta is in charge of providing the oxygen-rich blood.

The fetal heart will send oxygen-poor blood into the placenta, the blood cells then pick up oxygen and pumped back to the fetal hear via the liver and into the right side of the heart. The oxygen-rich blood cells are then pumped to the brain first and through the body.

The chambers in the heart which are used to make this relationship work, close shortly after birth to begin working as a normal heart.

How does the baby pump blood before the heart is developed?

An embryo/fetus’s heart and the cardiovascular system doesn’t work like it would after birth for many reasons. Before the heart has developed at week 3 of gestation it simply doesn’t need a heart (yet) as it gets all its nutrients from the placenta. They don’t have lungs so they do not need to pump blood into them to pick up the oxygen. This is often the cause of babies screaming when they are born as they are testing their lungs for the very first time.

The nutrients and blood coming in from the umbilical cord are not connected to the fetus’ own circular system (yet). It’s a complete reliance system and not a ‘helping hand’ and as a side note, one of the reasons why the mother’s health and diet are so important.


How long after conception is there a heartbeat?

The embryo will grow and have a heartbeat at around 3-4 weeks of gestation or week 5-6 of pregnancy. It is too small to notice but the mother may or may not begin to feel nauseous as a result.

Is it normal to not hear the heartbeat at 12 weeks?

It is not uncommon to not hear a heartbeat at 12 weeks with a handheld doppler. If this is the case, the likelihood is that an ultrasound scan is conducted to see the heart beat. However, you will not be able to hear the heartbeat at an ultrasound until much later as it could harm the baby at that stage of development.

Does a heartbeat indicate life?

This is more of a philosophical, religious or even a moral question that really depends on the person’s viewpoint. It all depends on what you think of being ‘alive’ is. A heartbeat proves that the fetus exists and ‘is not dead’ but many don’t think of it as being ‘alive’ in the sense of it being sentient. Some believe they are ‘alive’ when they stop becoming an embryo and become a fetus, some believe they are alive when their brain matures to a certain point while others don’t believe they are alive until they are born. It’s all about perspectives and beliefs.

How can I check my baby’s heartbeat at home?

Dopplers can be used from 12 weeks to listen to the baby’s heartbeat from home, but they are expensive and not worth the money. The cheapest and safest way to hear a baby’s heartbeat from the comfort of your own home is with a simple stethoscope. By around week 18-20 it should be loud enough to be picked up, but not always. As the fetus grows more and more it will be louder and easier to find with a stethoscope.

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