When does a baby have a heart?

Answer 1

A fetus's heart develops early (3-5 weeks after conception).

It starts out as a tube and then grows into 4 chambers around 5 weeks. It starts beating around 5 weeks but usually can't be heard until 7-9 weeks.

During weeks 20-24 a fetus's heart heart develops more fully. An ultrasound of the heart during this time can rule out some congenital heart defects (CHDs) just by looking at the shapes of the four chambers of the heart. (Some CHDs are not detectable by ultrasound.)

Before birth, the fetus's heart pumps blood oxygenated in Mom's lungs received via the placenta. During this time, an extra pathway (PDA) exiting the baby's heart is left open. After birth, this extra pathway closes and the heart pumps blood to the baby's lungs to get oxygen in the bloodstream.