The human heart is an intricate organ. Its right side receives blood flowing from the body and pumps it to the lungs to receive oxygen, while the left side receives the oxygen-rich blood from the lungs and pumps it into the body. Your unborn baby's heart begins its careful formation in early pregnancy, and starts to beat soon after. In a healthy pregnancy, his heartbeat will continue to strengthen.
Week 5
According to Medline Plus, your baby's heart begins to develop in the fifth week of pregnancy, along with her brain and spinal cord. This stage of development occurs shortly after her implantation into the uterus, and her blood cells have already begun to multiply for different functions.
Week 6
By week six of pregnancy, your baby's heart is pumping blood. His heartbeat may be visible on a vaginal ultrasound as small blinking light, and will have a regular rhythm sometime between weeks six and seven. If a vaginal ultrasound during the sixth week does not reveal a fetal heartbeat, your doctor may schedule you for an ultrasound in three to seven days to check the baby's heart development.
Week 7
By the seventh week of your pregnancy, American Pregnancy Association states that your baby's heartbeat will be assessed by your doctor to determine the health of the pregnancy. Once a heartbeat is definitively detected, the chance of the pregnancy continuing is 70 to 90 percent. A healthy heartbeat during this stage is 90 to 110 beats per minute. If your baby is five millimeters or longer and has no heartbeat, a miscarriage may be determined. If she is less than five millimeters long, your doctor may look for a heartbeat in a few days.
Week 8 and Beyond
At the eight week of pregnancy, your baby's heart, which began as a singular tubal structure, is increasing in length. It develops to include a wall separating two chambers and valves that keep blood moving throughout the chambers. By week nine of pregnancy, a normal heartbeat is between 140 and 170 beats per minute. A doctor may be able to hear your baby's heartbeat with a fetal Doppler around week 13 and a stethoscope around week 22 of pregnancy.
Development Factors
Keep in mind that the development of an unborn baby varies according to the mother's health and calculation of ovulation. Your baby may also develop a heart defect, especially if he is exposed to alcohol, drugs or industrial chemicals through the mother's body in early pregnancy. These abnormalities may only become apparent after birth, when the baby's heart takes over the placenta's job of oxygen exchange in his body.
